Senin, 11 Desember 2017

electronics for water pumps and air pumps AMNIMARJESLOW GOVERNMENT 91220017 LOR AIR AND WATER EL INSTRUMENT CONTROL PUMP IN ELECTRONIC 02096010014 LJBUSAF XAM$$$ PUSH AND PULL STEAM FOR MATIC YES UNTIL JES WOW

   
                                    

                                               Simple water and air pump patterns

Example MAHLE product :

                          



 

Motors for electric pumps for water and other liquids

Pumps for water (or other liquids) are driven by electric motors. These can be used in wet or dry rotor environments. More controlled flow of coolant, reduction of fuel consumption and pollution (CO2), longer pump life, and quieter operation are some of the advantages found in new, modern, hybrid and electric passenger cars with electrically driven water pumps. Highly innovative rotor protection for operation in liquid is used in the motor design to ensure reliable, long-life operation.

Electronics—the key to integrated systems solutions

Electric components account for a growing range of tasks in combustion engine drives. They operate separately from the combustion engine, off-load it, and significantly increase the drive’s efficiency throughout the system.

The first step in electrification is to replace hydraulic and pneumatic actuators with electric actuators. Because they allow faster, more precise control, electric actuators improve combustion, for example, thus reducing fuel consumption and emissions.

“intelligent”: Equipped with an electric motor, engine accessories can run independently of the engine speed and pressure. They can therefore be designed purely based on specific requirements and with extreme precision. They also support stop-start functions in the combustion engine and can be powered by the energy recuperated during braking phases.

Control and power electronics 

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HVAC systems (heating, ventilation, and air conditioning) are responsible for heating, ventilating, and air conditioning the vehicle and provide comfortable cabin temperatures in the summer heat and winter cold. In addition to comfort, they also improve passive safety, because driver performance lasts longer with their help, and they keep the windshield free of ice and fog in the wintertime. In the field of power electronic components for HVAC systems, MAHLE provides PTC auxiliary heaters and associated control electronics for both combustion and electric vehicles. They heat up the cabin air to the desired temperature very quickly and require very little energy. Regulators from MAHLE for fan motors in the HVAC system set the fan speed very precisely to meet the requirements of the air conditioning system. They also protect the system from damage due to overheating, for example.
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Just a few years ago, vehicle engine cooling was relatively simple in design and its primary task was to protect the engine block against overheating. With requirements for fuel consumption, emissions, and passenger comfort, as well as increasing electrification of the powertrain, cooling of the powertrain has transformed more and more into complex thermal management. Precise control of the cooling air flows in the cooling circuit is increasing in significance. High-performance control units from MAHLE for fan motors allow switching of cooling air flows to meet demand, enable rapid engine warm-up, reduce consumption and CO2 emissions, and prevent overheating of the cooling system.
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Today’s exhaust gas aftertreatment systems are an important part of the overall engine system for further reducing pollutant emissions. In order to reach the operating temperatures necessary for cleaning diesel particulate filters even in short-range operations, MAHLE is developing control units that handle the temperature management of the system. They do this, for example, by briefly raising engine output at idle so that more hot exhaust gases reach the filter, by injecting chemical substances to promote particle burn-off, or by increasing the temperature in the exhaust gas tract by injecting fuel or with electrical heaters in the exhaust gas system. addition to electric controls, MAHLE also supplies the sensor elements needed for particulate filter management.
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Glow controllers from MAHLE support the starting process in diesel engines at cold temperatures. They enable better combustion of the diesel fuel mixture, thus reducing emissions. The controllers are designed for glow plugs with a voltage of 4.4 volts, which reach their full glow temperature very quickly. The systems from MAHLE can actuate up to four glow plugs—both metal and ceramic—independently of each other. A protection system shields the individual channels and ensures robust and reliable protection against short circuits and overheating. Glow controllers from MAHLE are designed for operating voltages from 6 to 16 volts. A wider temperature range from –40°C to +90°C allows them to be positioned flexibly in the engine compartment.
Horns are legally mandated for cars and increase safety in street traffic, because the driver can warn other vehicle operators acoustically in case of danger. MAHLE supplies both electronic horns and the associated control electronics. Due to their robust construction, the service life has been increased by a factor of 20 in comparison with conventional concepts.
Sensors capture important measurement parameters in the vehicle and pass them along to the controlling devices. This makes them an important part of today’s vehicle electronics. The MAHLE product range includes temperature sensors, thick-film resistors for tank level indicators, steering angle sensors, and encoders—for example for electric window lifts. 


Fuel management

A central aspect of fuel management is the efficient filtration of the fuel, in order to protect the engine and its components from contamination and damage. As manufacturers increasingly pursue a strategy of identical parts or modular design, the same engine is being used in more and more regions of the world. The fuel quality varies accordingly, at times due to biocomponents in the fuel. The water content plays a role along with dirt particles. Water separation systems can pave the way for the global application of an engine while making it possible to use biodiesel .


product range for fuel management includes products such as fuel filters, water separation systems, fuel heaters, and activated carbon canisters.

Fuel filter modules efficiently prepare gasoline and diesel fuels for the combustion process. For this purpose, they use high-separation filter media and feature an advanced functionality scope. The fuel pressure in gasoline filters can thus be adjusted by a pressure regulator integrated in the fuel filter.
For diesel engines, the functional range of the MAHLE fuel filter modules can be significantly more complex. The fuel can be cooled or heated, for example, or the water content of the fuel can be separated.
In order to comply with demanding emissions limits, modern diesel engines typically employ common rail injection systems. These are extremely sensitive to solid particles and diesel fuel containing unsolved water. Since world engines are also used in countries with poor fuel quality and varying shares of biofuel, it is necessary to enable optimal separation of contaminants and water even under these conditions.
For this purpose, MAHLE has developed a solution with the active prefilter module that achieves a separation level of up to 98 percent in new condition.
Every fuel tank has a pressure balance pipe, which ensures that no vacuum develops as the tank is emptied, and that heating and expansion of the fuel does not create overpressure in the tank. The fuel fumes that escape when the overpressure is relieved are fed through a pipe to the activated carbon canister, where they are captured or stored. The fuel fumes stored in the filter are then burned during engine operation. Activated carbon canister modules thus reliably reduce the emission of hydrocarbons and pollutants.

MAHLE power for e-mobility

MEET – MAHLE Efficient Electric Transport

MAHLE Electronics—the key to integrated systems solutions

Battery-management systems from MAHLE monitor and control temperatures, voltages, charge states, and charging and discharging processes for lithium-ion cells. They ensure reliable, trouble-free functionality and optimal performance of automotive traction batteries, even under peak currents. Thick-film resistors on a ceramic substrate make the system extremely robust and rugged.

MAHLE thermal management: enabler for electromobility

There are also nearly as many proprietary protocols as there are companies making POS peripherals. Most POS peripherals, such as displays and printers, support several of these command protocols in order to work with many different brands of POS terminals and computers.

User interface design

The design of the sale window is the most important one for the user. This user interface is highly critical when compared to those in other software packages such as word editors or spreadsheet programs where speed of navigation is not so crucial for business performance.
For businesses at prime locations where real estate comes at a premium, it can be common to see a queue of customers. The faster a sale is completed the shorter the queue and hence the more room available in a store for customers to shop around and employees to do their work. High-traffic operations like such as grocery outlets and cafes need to process sales quickly at the sales counter so the UI flow is often designed with as few popups or other interruptions to ensure the operator isn't distracted and the transaction can be processed as quickly as possible.
Although improving the ergonomics is possible, a clean, fast-paced look may come at the expense of sacrificing functions that are often wanted by end-users such as discounts, access to commission earned screens, membership and loyalty schemes can involve looking at a different function of the POS to ensure the point of sale screen contains only what a cashier needs at their disposal to serve customers.

Cloud-based (post-2000s)

The advent of cloud computing has given birth to the possibility of POS systems to be deployed as software as a service, which can be accessed directly from the Internet, using any internet browser. Using the previous advances in the communication protocols for POS's control of hardware, cloud-based POS systems are independent from platform and operating system limitations. Cloud-based POS systems are also created to be compatible with a wide range of POS hardware and sometimes tablets such as Apple's IPad. Thus cloud-based POS also helped expand POS systems to mobile devices, such as tablet computers or smartphones.[12] These devices can also act as barcode readers using a built-in camera and as payment terminals using built-in NFC technology or an external payment card reader. A number of POS companies built their software specifically to be cloud-based. Other businesses who launched pre-2000s have since adapted their software to evolving technology.
Cloud-based POS systems are different from traditional POS largely because user data, including sales and inventory, are not stored locally, but in a remote server. The POS system is also not run locally, so there is no installation required.[13][14]
Depending on the POS vendor and the terms of contract, compared to traditional on-premises POS installation, the software is more likely to be continually updated by the developer with more useful features and better performance in terms of computer resources at the remote server and in terms of lesser bugs and errors.
Other advantages of a cloud-based POS are instant centralization of data (important especially to chain stores), ability to access data from anywhere there is internet connection, and lower start-up costs.[14][15]
Cloud based POS requires an internet connection. For this reason it important to use a device which has its own 3G capability in case the device's primary internet goes down. In addition to being significantly less expensive than traditional legacy point of sale systems, the real strength of a cloud based point of sale system is that there are developers all over the world creating software applications for cloud based POS. Cloud based POS systems are often described[by whom?] as future proof as new applications are constantly being conceived and built.
A number of noted emerging cloud-based POS systems came on the scene less than a decade or even half a decade back. These systems are usually designed for restaurants, small and medium-sized retail operations with fairly simple sale processes as can be culled from POS system review sites. It appears from such software reviews that enterprise-level cloud-based POS systems are currently lacking in the market. "Enterprise-level" here means that the inventory should be capable of handling a large number of records, such as required by grocery stores and supermarkets. It can also mean that the system--software and cloud server--must be capable of generating reports such as analytics of sale against inventory for both a single and multiple outlets that are interlinked for administration by the headquarters of the business operation.
POS vendors of such cloud based systems should also have a strong contingency plan for the breakdown of their remote server such as represented by failover server support. However, sometimes even a major data center can fail completely, such as in a fire.[16] On-premises installations are therefore sometimes seen alongside cloud-based implementation to preempt such incidents, especially for businesses with very high traffic. However the on-premises installations may not have the most up-to-date inventory and membership information.
For such contingency, a more innovative though highly complex approach for the developer is to have a trimmed down version of the POS system installed on the cashier computer at the outlet. On a daily basis the latest inventory and membership information from the remote server is automatically updated into the local database. Thus should the remote server fail, the cashier can switch over to the local sale window without disrupting sales. When the remote server is restored and the cashier switches over to the cloud system, the locally processed sale records are then automatically submitted to the remote system, thus maintaining the integrity of the remote database.
Although cloud-based POS systems save the end-user startup cost and technical challenges in maintaining an otherwise on-premises installation, there is a risk that should the cloud-based vendor close down it may result in more immediate termination of services for the end-user compared to the case of a traditional full on-premises POS system where it can still run without the vendor.
Another consideration is that a cloud-based POS system actually exposes business data to service providers - the hosting service company and the POS vendor which have access to both the application and database. The importance of securing critical business information such as supplier names, top selling items, customer relationship processes cannot be underestimated given that sometimes the few key success factors or trade secrets of a business are actually accessible through the POS system. This security and privacy concern is an ongoing issue in cloud computing.

Retail industry

The retail industry is one of the predominant users of POS terminals.
A woman stands behind a shopping cart at the checkout stand.
A woman in Jordan is ready to pay for her groceries.
A retail point of sale system typically includes a cash register (which in recent times comprises a computer, monitor, cash drawer, receipt printer, customer display and a barcode scanner) and the majority of retail POS systems also include a debit/credit card reader. It can also include a conveyor belt, weight scale, integrated credit card processing system, a signature capture device and a customer pin pad device. While the system may include a keyboard and mouse, more and more POS monitors use touch-screen technology for ease of use, and a computer is built into the monitor chassis for what is referred to as an all-in-one unit. All-in-one POS units liberate counter space for the retailer. The POS system software can typically handle a myriad of customer based functions such as sales, returns, exchanges, layaways, gift cards, gift registries, customer loyalty programs, promotions, discounts and much more. POS software can also allow for functions such as pre-planned promotional sales, manufacturer coupon validation, foreign currency handling and multiple payment types.
The POS unit handles the sales to the consumer but it is only one part of the entire POS system used in a retail business. "Back-office" computers typically handle other functions of the POS system such as inventory control, purchasing, receiving and transferring of products to and from other locations. Other typical functions of a POS system are: store sales information for enabling customer returns, reporting purposes, sales trends and cost/price/profit analysis. Customer information may be stored for receivables management, marketing purposes and specific buying analysis. Many retail POS systems include an accounting interface that "feeds" sales and cost of goods information to independent accounting applications.
A multiple point of sale system used by big retailers like supermarkets and department stores has a far more demanding database and software architecture than that of a single station seen in small retail outlets. A supermarket with high traffic cannot afford a systemic failure, hence each point of sale station should not only be very robust both in terms of software, database and hardware specifications but also designed in such a way as to prevent causing a systemic failure - such as may happen through the use of a single central database for operations.
At the same time updating between multiple stations and the backend administrative computer should be capable of being efficiently performed, so that on one hand either at the start of the day or at any time each station will have the latest inventory to process all items for sale, while on the other hand at the end of the day the backend administrative computer can be updated in terms of all sale records.
This gets even more complicated when there is a membership system requiring real-time two-way updating of membership points between sale stations and the backend administrative computer.
Retail operations such as hardware stores (lumber yards), electronic stores and so-called multifaceted superstores need specialized additional features compared to other stores. POS software in these cases handles special orders, purchase orders, repair orders, service and rental programs as well as typical point of sale functions.[17] Rugged hardware is required for point of sale systems used in outdoor environments. Wireless devices, battery powered devices, all-in-one units, and Internet-ready machines are typical in this industry.
Recently new applications have been introduced, enabling POS transactions to be conducted using mobile phones and tablets. According to a recent study, mobile POS (mPOS) terminals are expected to replace the contemporary payment techniques because of various features including mobility, upfront low cost investment and better user experience. Convenience of conducting remote financial transactions is expected to augment the demand from small and medium businesses for mPOS.
In the mid-2000s, the blind community in the United States engaged in structured negotiations to ensure that retail point of sale devices had tactile keypads. Without keys that can be felt, a blind person cannot independently enter her or his PIN. In the mid-2000s retailers began using "flat screen" or "signature capture" devices that eliminated tactile keypads. Blind people were forced to share their confidential PIN with store clerks in order to use their debit and other PIN-based cards. The blind community reached agreement with Walmart, Target, CVS and eight other retailers that required real keys so blind people could use the devices.

Physical configuration

Early stores typically kept merchandise behind a counter. Staff would fetch items for customers to prevent the opportunity for theft and sales would be made at the same counter. Self-service grocery stores such as Piggly Wiggly, beginning in 1916, allowed customers to fetch their own items and pass the point of sale on the way to the exit. Many stores have a number of cash registers for checkout, possibly now including self-checkout. This requires customers to guess which line will move the fastest, if they want to minimize their wait times; they are often frustrated to be wrong or be stuck behind another customer who encounters a problem or who takes a long time to check out. Some stores use a single, much longer but faster-moving line, that is served by multiple registers, which produces the same average wait time, but reduces the frustration and variance in wait time from person to person.[20] Regardless of the configuration, checkout lines usually pass by impulse buy items to grab the attention of otherwise idle customers.

Hospitality industry

Reception desk POS
Restaurant POS
Tablet-based POS
Hospitality point of sale systems are computerized systems incorporating registers, computers and peripheral equipment, usually on a computer network to be used in restaurants, hair salons or hotels. Like other point of sale systems, these systems keep track of sales, labor and payroll, and can generate records used in accounting and bookkeeping. They may be accessed remotely by restaurant corporate offices, troubleshooters and other authorized parties.
Point of sale systems have revolutionized the restaurant industry, particularly in the fast food sector. In the most recent technologies, registers are computers, sometimes with touch screens. The registers connect to a server, often referred to as a "store controller" or a "central control unit". Printers and monitors are also found on the network. Additionally, remote servers can connect to store networks and monitor sales and other store data.
Typical restaurant POS software is able to create and print guest checks, print orders to kitchens and bars for preparation, process credit cards and other payment cards, and run reports. In addition, some systems implement wireless pagers and electronic signature-capture devices.
In the fast food industry, displays may be at the front counter, or configured for drive-through or walk-through cashiering and order taking. Front counter registers allow taking and serving orders at the same terminal, while drive-through registers allow orders to be taken at one or more drive-through windows, to be cashiered and served at another. In addition to registers, drive-through and kitchen displays are used to view orders. Once orders appear they may be deleted or recalled by the touch interface or by bump bars. Drive-through systems are often enhanced by the use of drive-through wireless (or headset) intercoms. The efficiency of such systems has decreased service times and increased efficiency of orders.
Another innovation in technology for the restaurant industry is wireless POS. Many restaurants with high volume use wireless handheld POS to collect orders which are sent to a server. The server sends required information to the kitchen in real time. Wireless systems consist of drive-through microphones and speakers (often one speaker will serve both purposes), which are wired to a "base station" or "center module." This, in turn, will broadcast to headsets. Headsets may be an all-in-one headset or one connected to a belt pack.
In hotels, POS software allows for transfer of meal charges from dining room to guest room with a button or two. It may also need to be integrated with property management software.
Newer, more sophisticated systems are getting away from the central database "file server" type system and going to what is called a "cluster database". This eliminates any crashing or system downtime that can be associated with the back office file server. This technology allows 100% of the information to not only be stored, but also pulled from the local terminal, thus eliminating the need to rely on a separate server for the system to operate.
Tablet POS systems popular for retail solutions are now available for the restaurant industry. Initially these systems were not sophisticated and many of the early systems did not support a remote printer in the kitchen. Tablet systems today are being used in all types of restaurants including table service operations. Most tablet systems upload all information to the Internet so managers and owners can view reports from anywhere with a password and Internet connection. Smartphone Internet access has made alerts and reports from the POS very accessible. Tablets have helped create the Mobile POS system, and Mobile POS applications also include payments, loyalty, online ordering, table side ordering by staff and table top ordering by customers. Regarding the payments, mobile POS can accept all kinds of payment methods from contactless cards, EMV chip-enabled cards, and mobile NFC enabled cards. Mobile POS (AKA mPOS) is growing quickly with new developers entering the market almost on a daily basis.
With the proliferation of low-priced touchscreen tablet computers, more and more restaurants have implemented self-ordering through tablet POS placed permanently on every table. Customers can browse through the menu on the tablet and place their orders which are then sent to the kitchen. Most restaurants that have iPad self-order menus include photos of the dishes so guests can easily choose what they want to order. This apparently improves service and saves manpower on the part of the restaurant. However this depends on how intelligently the system has been programmed to be.
Self order menu
As a case in point, some self-ordering systems not requiring staff assistance may not properly recognize a subsequent order from the same customer at a table. As a result, the customer is left waiting and wondering why his second order of food and drink is not being served.
Another example of how intelligent the system can be, is whether an order that has been placed but not yet been processed by the kitchen can be modified by the customer through the tablet POS. For such an unprocessed order the customer should be given the option to easily retrieve his order and modify it on the tablet POS. But when his order is being processed this function should then be automatically disabled.
Self-ordering systems are not always free completely from intervention by the staff and for some good reasons. For example, some restaurants require that items selected by the customers be attended to and can only be placed by the waiter who has the password required to do so. This prevents fake orders - such as may be entered by playful kids - and subsequent dispute on the items ordered. If alcoholic drinks are ordered, it also becomes necessary for the waiter to first verify the age of the customer before sending the order.
The technical specifications for implementing such self-ordering system are more demanding than a single cashier-controlled POS station. On the software and hardware side each tablet on a customer table has to be networked to the cashier POS station and the kitchen computer so that both are continually updated on orders placed. The common database that serves this network must also be capable of serving many concurrent users - cashier, customers, kitchen and perhaps even a drink bar.
It is therefore to be noted by developers that some databases like popularly used Ms Access may have the specifications that it is capable of usage by multiple concurrent users. However under the stress of a POS system, they can fail miserably resulting in constant errors and corruption of data.
POS systems are often designed for a variety of clients, and can be programmed by the end users to suit their needs. Some large clients write their own specifications for vendors to implement. In some cases, POS systems are sold and supported by third-party distributors, while in other cases they are sold and supported directly by the vendor.
The selection of a restaurant POS system is critical to the restaurant's daily operation and is a major investment that the restaurant's management and staff must live with for many years. The restaurant POS system interfaces with all phases of the restaurant operation and with everyone that is involved with the restaurant including guests, suppliers, employees, managers and owners. The selection of a restaurant POS system is a complex process that should be undertaken by the restaurant owner and not delegated to an employee. The purchase process can be summarized into three steps: Design, Compare and Negotiate. The Design step requires research to determine which restaurant POS features are needed for the restaurant operation. With this information the restaurant owner or manager can Compare various restaurant POS solutions to determine which POS systems meet their requirements. The final step is to Negotiate the price, payment terms, included training, initial warranty and ongoing support costs.

Accounting forensics

POS systems record sales for business and tax purposes. Illegal software dubbed "zappers" can be used on POS devices to falsify these records with a view to evading the payment of taxes.

Security

Despite the more advanced technology of a POS system as compared to a simple cash register, the POS system is still as vulnerable to employee theft through the sale window. A dishonest cashier at a retail outlet can collude with a friend who pretends to be just another customer. During checkout the cashier can bypass scanning certain items or enter a lower quantity for some items thus profiting thereby from the "free" goods.
The ability of a POS system to void a closed sale receipt for refund purpose without needing a password from an authorized superior also represents a security loophole. Even a function to issue a receipt with a negative amount which can be useful under certain circumstances, can be exploited by a cashier to easily lift money from the cash drawer.
In order to prevent such employee theft, it is crucial for a POS system to provide an admin window for the boss or administrator to generate and inspect a daily list of sale receipts, especially pertaining to the frequency of cancelled receipts before completion, refunded receipts and negative receipts. This is one effective way to alert the company to any suspicious activity - such as a high number of cancelled sales by a certain cashier - that may be going on and to take monitoring action.
To further deter employee theft the sale counter should also be equipped with a closed-circuit television camera pointed at the POS system to monitor and record all the activities.
At the backend, price and other changes like discounts to inventory items through the administration module should also be secured with passwords provided only to trusted administrators. Any changes made should also be logged and capable of being subsequently retrieved for inspection.
The sale records and inventory are highly important to the business because they provide very useful information to the company in terms of customer preferences, customer membership particulars, what are the top selling products, who are the vendors and what margins the company is getting from them, the company monthly total revenue and cost, just to name some.
It is therefore important that reports on these matters generated at the administrative backend be restricted only to trusted personnel. The database from which these reports are generated should also be secured via passwords or via encryption of data stored in the database so as to prevent them from being copied or tampered with.
Despite all such precautions and more, the POS system can never be entirely water tight in security from internal misuse if a clever but dishonest employee knows how to exploit many of its otherwise useful capabilities.
News reports on POS system hacking show that hackers are more interested in stealing credit card information than anything else. The ease and advantage offered by the ability of a POS system to integrate credit card processing thus has a downside. In 2011, hackers were able to steal credit card data from 80,000 customers because Subway's security and POS configuration standards for PCI Compliance - which governs credit card and debit card payment systems security - were "directly and blatantly disregarded" by Subway franchisees.
In June 2016, several hundred of Wendy's fast food restaurants had their POS systems hacked by an illegally installed malware.[24] The report goes on to say that "the number of franchise restaurants impacted by these cybersecurity attacks is now expected to be considerably higher than the 300 restaurants already implicated" and that the "hackers made hundreds of thousands of fraudulent purchases on credit and debit cards issued by various financial institutions after breaching Wendy's computer systems late last year".
Again this exploit by hackers could only be made possible because payment cards were processed through the POS system allowing the malware to either intercept card data during processing or steal and transmit unencrypted card data that is stored in the system database.
In April 2017, security researchers identified critical vulnerabilities in point of sale systems developed by SAP and Oracle [25] and commented, “POS systems are plagued by vulnerabilities, and incidents occurred because their security drawbacks came under the spotlight.”  If successfully exploited, these vulnerabilities provide a perpetrator with access to every legitimate function of the system, such as changing prices, remotely start and stop terminals. To illustrate the attack vector, the researchers used the example of hacking POS to change the price of a MacBook to $1. [28] The security issues were reported to the vendor, and a patch was released soon after the notification.
In some countries credit and debit cards are only processed via payment terminals. Thus one may see quite a number of such terminals for different cards cluttering up a sale counter. This inconvenience is however offset by the fact that credit and debit card data is far less vulnerable to hackers, unlike when payment cards are processed through the POS system where security is contingent upon the actions taken by end-users and developers.
With the launch of mobile payment particularly Android Pay and Apple Pay both in 2015, it is expected that because of its greater convenience coupled with good security features, this would eventually eclipse other types of payment services - including the use of payment terminals. However, for mobile payment to go fully mainstream, mobile devices like smartphones that are NFC-enabled must first become universal. This would be a matter of several years from the time of this writing (2017) as more and more models of new smartphones are expected to become NFC-enabled for such a purpose. For instance iPhone 6 is fully NFC-enabled for mobile payment while iPhone 5 and older models are not. The aforesaid disastrous security risks connected with processing payment card usage through a POS system would then be greatly diminished.
 
 
 
                      XXX  .  V00000  How does a gas pump know to shut itself off?  
 
so cleanse your mind of distracting thoughts. In a gas pump handle you have two valves: the main valve, which is actuated by the oversize trigger you squeeze to make the gas flow, and the check valve, which lets gas flow out but won't let anything back in again, thus reducing fire hazard. In the seat of the check valve you have a little hole. To the backside of this hole is connected a Y-shaped tube. One branch of this tube runs down the nozzle and exits at the tip while the other runs back to a diaphragm connected to a release mechanism on the main valve. When you squeeze the gas pump trigger, gas running past the hole in the check valve sucks air out of the Y-shaped tube. (This is because of the Bernoulli principle: a moving stream of fluid tends to pull things in from the sides. Take my word for it.) As long the end of the Y-shaped tube exiting at the spout is unobstructed, air is simply pulled into the tube and nothing much else happens. However, as soon as the gas in your car's fill-up pipe gets high enough to cover the end of the tube, a partial vacuum is created therein, which yanks on the diaphragm, releases the main valve, and shuts off the gas. If the gas happens to be especially foamy one day, it may actuate the release mechanism prematurely, with the result that you end up with less than a full tank of gas. Simple  . 
 
 
                                                              Fuel pump 
 
A fuel pump is a frequently (but not always) essential component on a car or other internal combustion engined device. Many engines (older motorcycle engines in particular) do not require any fuel pump at all, requiring only gravity to feed fuel from the fuel tank or under high pressure to the fuel injection system. Often, carbureted engines use low pressure mechanical pumps that are mounted outside the fuel tank, whereas fuel injected engines often use electric fuel pumps that are mounted inside the fuel tank (and some fuel injected engines have two fuel pumps: one low pressure/high volume supply pump in the tank and one high pressure/low volume pump on or near the engine)
 
    A high-pressure fuel pump on a Yanmar 2GM20 marine diesel engine 
 

Mechanical pump

Mechanical fuel pump, fitted to cylinder head
Prior to the widespread adoption of electronic fuel injection, most carbureted automobile engines used mechanical fuel pumps to transfer fuel from the fuel tank into the fuel bowls of the carburetor. Most mechanical fuel pumps are diaphragm pumps, which are a type of positive displacement pump. Diaphragm pumps contain a pump chamber whose volume is increased or decreased by the flexing of a flexible diaphragm, similar to the action of a piston pump. A check valve is located at both the inlet and outlet ports of the pump chamber to force the fuel to flow in one direction only. Specific designs vary, but in the most common configuration, these pumps are typically bolted onto the engine block or head, and the engine's camshaft has an extra eccentric lobe that operates a lever on the pump, either directly or via a pushrod, by pulling the diaphragm to bottom dead center. In doing so, the volume inside the pump chamber increased, causing pressure to decrease.This allows fuel to be pushed into the pump from the tank (caused by atmospheric pressure acting on the fuel in the tank). The return motion of the diaphragm to top dead center is accomplished by a diaphragm spring, during which the fuel in the pump chamber is squeezed through the outlet port and into the carburetor. The pressure at which the fuel is expelled from the pump is thus limited (and therefore regulated) by the force applied by the diaphragm spring.
The carburetor typically contains a float bowl into which the expelled fuel is pumped. When the fuel level in the float bowl exceeds a certain level, the inlet valve to the carburetor will close, preventing the fuel pump from pumping more fuel into the carburetor. At this point, any remaining fuel inside the pump chamber is trapped, unable to exit through the inlet port or outlet port. The diaphragm will continue to allow pressure to the diaphragm, and during the subsequent rotation, the eccentric will pull the diaphragm back to bottom dead center, where it will remain until the inlet valve to the carburetor reopens.
Because one side of the pump diaphragm contains fuel under pressure and the other side is connected to the crankcase of the engine, if the diaphragm splits (a common failure), it can leak fuel into the crankcase. The capacity of both mechanical and electric fuel pump is measured in psi (which stands for pounds per square inch). Usually this unit is general measurement for pressure, yet it has slightly different meaning, when talking about fuel pumps[2]. In this context it denotes the speed, at which the pump delivers fuel from the tank to the engine. This is one of fuel pump characteristics. The higher pressure is, the faster fuel flows.
The pump creates negative pressure to draw the fuel through the lines. However, the low pressure between the pump and the fuel tank, in combination with heat from the engine and/or hot weather, can cause the fuel to vaporize in the supply line. This results in fuel starvation as the fuel pump, designed to pump liquid, not vapor, is unable to suck more fuel to the engine, causing the engine to stall. This condition is different from vapor lock, where high engine heat on the pressured side of the pump (between the pump and the carburetor) boils the fuel in the lines, also starving the engine of enough fuel to run. Mechanical automotive fuel pumps generally do not generate much more than 10-15 psi, which is more than enough for most carburetors.

Decline of mechanical pumps

As engines moved away from carburetors and towards fuel injection, mechanical fuel pumps were replaced with electric fuel pumps, because fuel injection systems operate more efficiently at higher fuel pressures (40-60 psi) than mechanical diaphragm pumps can generate. Electric fuel pumps are generally located in the fuel tank, in order to use the fuel in the tank to cool the pump and to ensure a steady supply of fuel.
Another benefit of an in-tank mounted fuel pump is that a suction pump at the engine could suck in air through a (difficult to diagnose) faulty hose connection, while a leaking connection in a pressure line will show itself immediately. A potential hazard of a tank-mounted fuel pump is that all of the fuel lines are under (high) pressure, from the tank to the engine. Any leak will be easily detected, but is also hazardous.

Electric pump

Electric fuel pump
A piston metering pump f.e. gasoline- or additive metering pump
In many modern cars the fuel pump is usually electric and located inside the fuel tank. The pump creates positive pressure in the fuel lines, pushing the gasoline to the engine. The higher gasoline pressure raises the boiling point. Placing the pump in the tank puts the component least likely to handle gasoline vapor well (the pump itself) farthest from the engine, submersed in cool liquid. Another benefit to placing the pump inside the tank is that it is less likely to start a fire. Though electrical components (such as a fuel pump) can spark and ignite fuel vapors, liquid fuel will not explode (see flammability limit) and therefore submerging the pump in the tank is one of the safest places to put it. In most cars, the fuel pump delivers a constant flow of gasoline to the engine; fuel not used is returned to the tank. This further reduces the chance of the fuel boiling, since it is never kept close to the hot engine for too long.
The ignition switch does not carry the power to the fuel pump; instead, it activates a relay which will handle the higher current load. It is common for the fuel pump relay to become oxidized and cease functioning; this is much more common than the actual fuel pump failing. Modern engines utilize solid-state control which allows the fuel pressure to be controlled via pulse-width modulation of the pump voltage. This increases the life of the pump, allows a smaller and lighter device to be used, and reduces electrical load.
Cars with electronic fuel injection have an electronic control unit (ECU) and this may be programmed with safety logic that will shut the electric fuel pump off, even if the engine is running. In the event of a collision this will prevent fuel leaking from any ruptured fuel line. Additionally, cars may have an inertia switch (usually located underneath the front passenger seat) that is "tripped" in the event of an impact, or a roll-over valve that will shut off the fuel pump in case the car rolls over.
Some ECUs may also be programmed to shut off the fuel pump if they detect low or zero oil pressure, for instance if the engine has suffered a terminal failure (with the subsequent risk of fire in the engine compartment).
The fuel sending unit assembly may be a combination of the electric fuel pump, the filter, the strainer, and the electronic device used to measure the amount of fuel in the tank via a float attached to a sensor which sends data to the dash-mounted fuel gauge. The fuel pump by itself is a relatively inexpensive part. But a mechanic at a garage might have a preference to install the entire unit assembly.
 
  

Centrifugal turbopumps

In centrifugal turbopumps a rotating disk throws the fluid to the rim
Most turbopumps are centrifugal - the fluid enters the pump near the axis and the rotor accelerates the fluid to high speed. The fluid then passes through a diffuser which is a progressively enlarging pipe, which permits recovery of the dynamic pressure. The diffuser turns the high kinetic energy into high pressures (hundreds of bars is not uncommon), and if the outlet backpressure is not too high, high flow rates can be achieved.

Axial turbopumps

Axial compressors
Axial turbopumps also exist. In this case the axle essentially has propellers attached to the shaft, and the fluid is forced by these parallel with the main axis of the pump. Generally, axial pumps tend to give much lower pressures than centrifugal pumps, and a few bars is not uncommon. They are, however, still useful – axial pumps are commonly used as "inducers" for centrifugal pumps, which raise the inlet pressure of the centrifugal pump enough to prevent excessive cavitation from occurring therein.

Complexities of centrifugal turbopumps

Turbopumps have a reputation for being extremely hard to design to get optimal performance. Whereas a well engineered and debugged pump can manage 70–90% efficiency, figures less than half that are not uncommon. Low efficiency may be acceptable in some applications, but in rocketry this is a severe problem. Turbopumps in rockets are important and problematic enough that launch vehicles using one have been caustically described as a "turbopump with a rocket attached"–up to 55% of the total cost has been ascribed to this area.
Common problems include:
  1. excessive flow from the high-pressure rim back to the low-pressure inlet along the gap between the casing of the pump and the rotor,
  2. excessive recirculation of the fluid at inlet,
  3. excessive vortexing of the fluid as it leaves the casing of the pump,
  4. damaging cavitation to impeller blade surfaces in low-pressure zones.
In addition, the precise shape of the rotor itself is critical.

Driving turbopumps

Steam turbine-powered turbopumps are employed when there is a source of steam, e.g. the boilers of steam ships. Gas turbines are usually used when electricity or steam is not available and place or weight restrictions permit the use of more efficient sources of mechanical energy.
One of such cases are rocket engines, which need to pump fuel and oxidizer into their combustion chamber. This is necessary for large liquid rockets, since forcing the fluids or gases to flow by simple pressurizing of the tanks is often not feasible; the high pressure needed for the required flow rates would need strong and heavy tanks.
Ramjet motors are also usually fitted with turbopumps, the turbine being driven either directly by external freestream ram air or internally by airflow diverted from combustor entry. In both cases the turbine exhaust stream is dumped overboard.
 

Expander cycle

   
Expander rocket cycle. Expander rocket engine (closed cycle). Heat from the nozzle and combustion chamber powers the fuel and oxidizer pumps.
The expander cycle is a power cycle of a bipropellant rocket engine. In this cycle, the fuel is used to cool the engine's combustion chamber, picking up heat and changing phase. The heated, now gaseous, fuel then powers the turbine that drives the engine's fuel and oxidizer pumps before being injected into the combustion chamber and burned.
Because of the necessary phase change, the expander cycle is thrust limited by the square-cube rule. As the size of a bell-shaped nozzle increases with increasing thrust, the nozzle surface area (from which heat can be extracted to expand the fuel) increases as the square of the radius. However, the volume of fuel that must be heated increases as the cube of the radius. Thus there exists a maximum engine size of approximately 300 kN of thrust beyond which there is no longer enough nozzle area to heat enough fuel to drive the turbines and hence the fuel pumps. Higher thrust levels can be achieved using a bypass expander cycle where a portion of the fuel bypasses the turbine and or thrust chamber cooling passages and goes directly to the main chamber injector. Non-toroidal aerospike engines do not suffer from the same limitations because the linear shape of the engine is not subject to the square-cube law. As the width of the engine increases, both the volume of fuel to be heated and the available thermal energy increase linearly, allowing arbitrarily wide engines to be constructed. All expander cycle engines need to use a cryogenic fuel such as hydrogen, methane, or propane that easily reach their boiling points.
Some expander cycle engines may use a gas generator of some kind to start the turbine and run the engine until the heat input from the thrust chamber and nozzle skirt increases as the chamber pressure builds up.
In an open cycle, or "bleed" expander cycle, only some of the fuel is heated to drive the turbines, which is then vented to atmosphere to increase turbine efficiency. While this increases power output, the dumped fuel leads to a decrease in propellant efficiency (lower engine specific impulse). A closed cycle expander engine sends the turbine exhaust to the combustion chamber (see image at right.)
Some examples of an expander cycle engine are the Pratt & Whitney RL10 and the Vinci engine for the future Ariane 6.
 
 

Expander bleed cycle (open cycle)

Expander bleed cycle. Expander open cycle (Also named coolant tap-off).
This operational cycle is a modification of the traditional expander cycle. In the bleed (or open) cycle, instead of routing heated propellant through the turbine and sending it back to be combusted, only a small portion of the propellant is heated and used to drive the turbine and is then bled off, being vented overboard without going through the combustion chamber. Bleeding off the turbine exhaust allows for a higher turbopump output by decreasing backpressure and maximizing the pressure drop through the turbine. Compared with a standard expander cycle, this leads to higher engine thrust at the cost of sacrificing some efficiency due to essentially wasting the bled propellant by not combusting it.

Dual expander (closed cycle)

In a similar way that the staged combustion can be implemented separately on the oxidizer and fuel on the full flow cycle, the expander cycle can be implemented on two separate paths as the dual expander cycle. The use of hot gases of the same chemistry as the liquid for the turbine and pump side of the turbopumps eliminates the need for purges and some failures modes. Additionally, when the density of the fuel and oxidizer is significantly different, as it is in the H2/LOX case, the optimal turbopump speeds differ so much that they need a gearbox between the fuel and oxidizer pumps.The use of dual expander cycle, with separate turbines, eliminates this failure-prone piece of equipment.
Dual expander cycle can be implemented by either using separated sections on the regenerative cooling system for the fuel and the oxidizer, or by using a single fluid for cooling and a heat exchanger to boil the second fluid. In the first case, for example, you could use the fuel to cool the combustion chamber, and the oxidizer to cool the nozzle. In the second case, you could use the fuel to cool the whole engine and a heat exchanger to boil the oxidizer.

Advantages

The expander cycle has a number of advantages over other designs:
Low temperature
The advantage is that after they have turned gaseous, the fuels are usually near room temperature, and do very little or no damage to the turbine, allowing the engine to be reusable. In contrast gas-generator or staged combustion engines operate their turbines at high temperature.
Tolerance
During the development of the RL10 engineers were worried that insulation foam mounted on the inside of the tank might break off and damage the engine. They tested this by putting loose foam in a fuel tank and running it through the engine. The RL10 chewed it up without problems or noticeable degradation in performance. Conventional gas-generators are in practice miniature rocket engines, with all the complexity that implies. Blocking even a small part of a gas generator can lead to a hot spot, which can cause violent loss of the engine. Using the engine bell as a 'gas generator' also makes it very tolerant of fuel contamination because of the wider fuel flow channels used.
Inherent safety
Because a bell-type expander-cycle engine is thrust limited, it can easily be designed to withstand its maximum thrust conditions. In other engine types, a stuck fuel valve or similar problem can lead to engine thrust spiraling out of control due to unintended feedback systems. Other engine types require complex mechanical or electronic controllers to ensure this does not happen. Expander cycles are by design incapable of malfunctioning that way. 


                                 XXX  .  V000000  Pumps and compressors 

   Man operating a pump in the desert 

Some inventions are glamorous—microchips and fiber-optic cables spring to mind. Others are quieter and more humble, but no less important. Pumps and compressors certainly fall into that category. Try to picture life without them and you won't get very far. Take away pumps and you'll have nothing to push hot water through your home central-heating pipes, and no way to remove the heat from your refrigerator. Might as well start walking too, because you won't be able to blow up the tires on your bicycle or put gasoline in your car. From jackhammers to air conditioners, all kinds of machines use pumps and compressors to move liquids and gases from place to place. Let's take a closer look at how they work!
Photo: A fuel pump operating in the desert. The pump is drawing liquid in through the hose on the left and pushing it out through the hoses on the right. Pumps play a vital part in supplying our energy by transporting liquids such as oil and natural gas down long pipelines. Photo by Derek D. Meitzer courtesy of US Marine Corps.

How to move solids, liquids, and gases

Suppose you want to move a solid block of metal. There's little choice in how to go about it: you have to pick it up and carry it. But if you want to move liquids or gases, things are a whole lot easier. That's because they move with only a little bit of help from us. We call liquids and gases fluids because they flow down channels and pipes from one place to another. They don't, however, move without some help. It takes energy to move things and usually we have to provide that ourselves. Sometimes liquids and gases do have stored potential energy that they can use to move themselves (for example, rivers flow downhill from source to sea by using the force of gravity), but often we want to move them to places where they wouldn't normally go—and for that we need pumps and compressors. (You can read more about solids, liquids, and gases in our article on states of matter.)

What's the difference between a pump and a compressor?

The air pressure gauge on the top of a typical foot pump
Sometimes the words "pump" and "compressor" are used interchangeably, but there is a difference:
  • A pump is a machine that moves a fluid (either liquid or gas) from one place to another.
  • A compressor is a machine that squeezes a gas into a smaller volume and (often) pumps it somewhere else at the same time.
While pumps can work on either liquids or gases, compressors generally work only on gases. That's because liquids are very difficult to compress. The atoms and molecules from which liquids are made are so tightly packed that you can't really squeeze them any closer together (an important piece of science that's put to very good use in hydraulic machines). Pressure washers, which make a powerful jet of water for cleaning things, are an exception: they work by squeezing liquids to higher pressures and speeds. Coffee machines also squeeze water to high pressure to make stronger and tastier drinks.
Photo: Pump or compressor? If it has a pressure gauge on it and the pressure increases as you pump, technically it's also working as a compressor. With this foot pump, as you inflate your car tires, you're pumping and compressing at the same time. Even so, you wouldn't really describe this as an air compressor, because it's job is really to move air from the atmosphere into your tires. A compressor is normally designed to make use of compressed air in some way, for example, by powering a jackhammer (pneumatic air drill).

How do pumps work?

There are really just two different kinds of pumps: reciprocating pumps (which pump by moving alternately back-and-forth) and rotary pumps (which spin around).

Reciprocating pumps

A red foot pump photographed on grass
Bicycle pumps are perhaps the most familiar examples of reciprocating pumps. They have a piston that moves back and forth inside a cylinder, alternately drawing in air from outside (when you pull out the handle) and pushing it into the rubber tire (when you push the handle back in again). One or more valves ensure that the air you've drawn into the pump doesn't go straight back out again the way it came. It's worth noting, incidentally, that bicycle pumps are actually air compressors because they force air from the atmosphere into the closed space of the rubber tire, reducing its volume and increasing its pressure.
Photo: Foot pumps are familiar examples of reciprocating pumps: they move air as you push your foot up and down. With this pump, you put your foot on the black lever at the top and pump your leg up and down, making the red cylinder move back and forth. A valve inside the cylinder lets air in (when you raise your leg), which is then pumped out through the black hose on the right (when you lower your leg). A gauge on the top of the pump (on the right) shows the air pressure in the tire in Imperial units (bars and pounds per square inch or psi).

Rotary pumps

A rotary pump used in firefighting.
Photo: A typical rotary pump used in firefighting. The impeller is inside the silver housing under the black circular case. Photo by Melrose Afaese courtesy of US Navy.
Rotary pumps work a completely different way using a spinning wheel to move the fluid from the inlet to the outlet. Devices like this are sometimes called centrifugal pumps because they fling the fluid outward by making it spin around (a bit like the way a clothes washer gets your jeans dry by spinning them at high speed). Rotary pumps work in exactly the opposite way to turbines. Where a turbine captures energy from a liquid or gas that's moving of its own accord (for example, the wind in the air around us or the water flowing in a river), a pump uses energy (typically supplied through an electric motor) to move a fluid from place to place.
Simplified line artwork showing the components inside a hydraulic gear motor. Artwork: A rotary pump can use meshing gears or screws to move fluid, much like a hydraulic motor.
Rotary pumps all tend to look the same from the outside: there's a sealed circular or cylindrical case with an inlet on one side and an outlet on the other. Inside, however, they can work in various different ways. Vane pumps use vanes (flat blades) that slide in and out as they rotate, moving the fluid from the inlet to the outlet and flinging it out at speed. Impeller pumps use a wheel with curved blades called an impeller, which is a bit like a multi-bladed propeller fitted snugly in the middle of a closed pipe. The impeller draws the fluid through the inlet, spins it around at speed, and then forces it out through the outlet pipe, usually pointed in the opposite direction. Sometimes impellers are made of rigid metal or plastic (like the one in the photo below), though they can also have flexible, rubbery blades that change length as they rotate (in a similar way to the sliding blades of a vane pump) so they always make a tight seal. In yet another design, the vanes and impellers are replaced by two or more large screws or gears that mesh and rotate in opposite directions, pulling fluid around them as they go. Auger pumps use a single long screw that transports material as it spins around, effectively like an auger mounted inside a pipe.

Which is best, rotary or reciprocating?

A rotary pump is much faster than a reciprocating pump because the fluid is continually entering and leaving; in a reciprocating pump, it's entering half the time and leaving the other half of the time. It's also easier to power with an electric motor than a reciprocating pump, because the motor is rotating as well; it's easy to drive one rotating machine with another, and somewhat harder to use a rotating machine (a motor) to drive a reciprocating one (a pump that needs moving back and forth). Generally, rotary pumps are mechanically simpler and more reliable than reciprocating ones because they don't have moving valves that will gradually wear out.
Animation comparing how reciprocating and rotary pumps move fluids.
Animation: Reciprocating and rotary pumps compared. Left: A simple back-and-forth reciprocating pump works in a two-step cycle. During the intake, the piston (dark blue) moves to the right. The inlet valve (green) opens and the valves in the piston (red) close up. The piston pulls fluid in from the inlet and pushes it through the outlet. On the return stroke, the piston moves to the left. Now the inlet valve closes and the valves in the piston open, so the fluid moves through the piston ready to be pumped to the outlet on the next stroke.
Right: A rotary pump shifts fluid from inlet to outlet like a paddle wheel. Watching what happens to a single segment, we can see that it fills with fluid one moment, before being pushed around to the outlet some time later. This is a very simplified example of what's called a vane pump: the vanes are the "blades" that turn on the wheel. You can see that half the chambers (the upper ones) are going to be empty all the time, which makes the pump less effective. For that reason, practical pumps tend to have the wheel mounted off-center, which makes a bigger, crescent-shaped chamber at the bottom, allowing more fluid to be pumped in the same time.

Using pumps and compressors

There are pumps inside virtually any machine that uses liquids, from car engines (which need to pump fuel) to dishwashers (where a pump cycles hot water round the tub) and personal water craft (powered through the water by a high-pressure jet of water pushing backward).
A typical white plastic impeller from inside a pump.
Photo: A typical pump impeller. Photo courtesy of NASA Marshall Image Gallery.
Unlike machines based around pumps, machines that use compressors don't work simply by moving a fluid: they also harness the energy that was stored inside the fluid when it was originally compressed. It takes energy to compress a gas, but that energy doesn't vanish into thin air and it isn't wasted. It's stored inside the gas and you can use it again later, whenever you like, by allowing the gas to move elsewhere (gas springs, used in office chairs and the hinges that hold open the tailgates of cars, are a good example of this).
Lots of machines (such as jackhammers) use highly pressurized air from a compressor to do useful jobs—we say they're pneumatic (a word that generally means air-powered machine). In a jackhammer, for example, the pressurized air pushes a drill bit back and forth when it's released through a long pipe. (You may have noticed that a jackhammer is attached to a big air compressor machine by a large air hose.) Compressed air is also used for cleaning things like stone blocks. Another really important use is in powering the air brakes in trains, trucks, and buses. To stop a really big vehicle quickly, you can't rely on the pressure supplied by a driver's leg, as you can in a car (where the brakes are hydraulic). Instead, truck and train brakes are powered by compressed air that's released when the driver pushes a pedal. You may have heard a sudden whooshing sound after trucks have stopped suddenly. That's compressed air being released after it pushes the brakes against the wheels to bring them to rest.
 
 
                                XXX  .  V000000  How Gas Pumps Work 
      NEXT PAGE  
      Filling up at the pump is a constant and somewhat annoying ritual for drivers.
      Filling up at the pump is a constant and somewhat annoying ritual for drivers.
      Justin Sullivan/Getty Images
      Your vacation has just begun and you're making the drive to the mountains or to the beach or to some other place that you've been dreaming about for months. You're ready to go, but before you can go more than a few miles, you have to head for the nearest exit -- it's already time to buy gas. With gasoline prices as volatile as they've been in recent years, this isn't likely to be your favorite part of the trip. There's even a chance that sticker shock at the pump may lead you to skip that evening's fancy dinner and stop for a fast-food meal instead. Unfortunately, in a world that depends on automobiles for basic transportation, pumping and purchasing gas is a necessary evil -- for the moment, anyway.
      During all those trips to the pump, have you ever stopped to wonder where the gas in the service station dispenser comes from or how it gets from the dispenser to your car's gas tank? The process isn't difficult to understand, but gas companies have gone to a great deal of trouble to hide the details. Pumping gas may seem like a simple matter of lifting a pump, pushing some buttons and sometimes swiping a credit card through a reader or waving a credit wand at a detector. What goes on inside the gas dispenser itself, however, is a bit more complicated than that. 

      The gasoline sold at service stations is stored underground in buried tanks. Each holds several thousand gallons of gas. There are at least two of these tanks per station and each tank usually holds a different grade of gas. Having the gas tanks underground presents an obvious problem: If the gas must get to a dispenser (and your car's gas tank) located above ground, it has to defy gravity in order to get there -- like a waterfall flowing uphill. But moving the gas from its subterranean hideaway up to street level isn't as difficult as you might think.
      Most service stations do the job using one of two types of pump -- a submersible pump or a suction pump:
      The Check Valve
      The route that the gas takes from the tanks to the aboveground dispenser isn't terribly complicated, though it may take a few minor twists and turns. When pumping is complete and the pump motor is turned off, the gas inside the pipe doesn't simply fall back into the tank. Instead, it's held inside the pipe by a check valve. The check valve, which is located above the gas inside the pipe, creates an airtight seal above the fluid. Although the bottom of the pipe remains open, the vacuum pressure created by the check valve holds the gas in place. This is a process known as keeping the prime.
      Using a check valve to hold the gas inside the pipe prevents unnecessary wear and tear on the suction pump and assures that a supply of gas will remain in the pipe so that the next customer won't have to wait for it to be drawn all the way up from the tank. It may not seem like a big deal, but the process can take 10 to 15 seconds. That isn't a very long wait by any means, but it can be an eternity when you're waiting for gas to be pumped.

      The Flow Meter
          
      Do you know how much gas you're pumping right now?
      Do you know how much gas you're pumping right now?
      Scott Olson/Getty Images
      As a driver, your primary objective at the pump is to get your tank filled so that you can get your car back on the road. The goal of the service station owner and the company that supplies the gas, however, is to know just how much gas you've pumped so they can properly charge you for it. That's where the flow meter comes in.
      As the gasoline travels upward into the dispenser, it passes through a flow control valve that regulates the gasoline's flow speed. It does this via a plastic diaphragm that gets squeezed more and more tightly into the pipe as the flow of gas increases, always leaving just enough room for the proper amount of gasoline to get through. If you've set a predetermined amount of gas to be pumped, the flow of gas will slow down as you approach the limit. 

      The Blend Valve

      One of the first things that a customer will notice at the pump is the variety of choices offered. In most cases, a dispenser will offer several grades of gas -- sometimes as many as five -- each with a different octane rating. The desired octane rating is usually chosen simply by pushing a button. Does this mean that there are five different underground tanks feeding into that dispenser, each offering a different grade of gas? That's not usually the case. In fact, the dispenser can produce as many grades as it wants from as few as two underground tanks, as long as one tank contains the highest grade of octane available at that station and the other contains the lowest. The grades are blended together at the pump -- not unlike the way you'd blend gin and vermouth to make a martini -- producing a kind of octane cocktail. The precise proportion in which the grades are blended determines the octane of the gas that enters the customer's tank.
      This feat of gas pump bartending is performed by something called a blend valve. This valve has inputs consisting of two grades of gasoline, each from different tanks. A single, moveable barrier called a shoe is connected to both in such a way that it can be moved across the inputs with a single motor-driven ratchet. As the ratchet opens one valve, it closes the other valve in precise but opposite proportion. This means that when one valve is, for example, 90 percent open, the other valve is 10 percent open, creating a mixture that consists of 90 percent of one octane and 10 percent of the other. By shifting the ratchet back and forth, the blend valve can produce any octane of gas, ranging from the highest to the lowest grades stored in the tanks -- and all octanes in between. 

      Safety Measures
      As the customer pumps the gas mixture of his or her choice into the car's gas tank, any number of accidents could happen -- most of them attributable to human error.
      For instance, hot ash from a lit cigarette could set the gasoline on fire, which is why smoking in the vicinity of a gasoline dispenser is illegal in most jurisdictions. Leaving the automobile's motor running while pumping gas isn't illegal, but that doesn't mean it's a good idea: Even minor motor malfunctions could create sparks or a brief burst of flame that could ignite the gas. Sparks from static electricity could also pose a danger, which is why you should touch the car's frame before operating the pump to discharge any static buildup. Don't wait inside the car on a cold day as the gas is pumped, either -- the very act of sliding across the car seat could generate a static charge comparable to one generated by walking across a plush carpet.
      If an absent-minded customer drives away with the nozzle still inserted in the tank, the hose is designed to break into two pieces. One remains with the car and the other with the dispenser. Check valves on both sides of the breaking point prevent fuel from leaking out of either half.

      The Automatic Shut-off 

      When the customer removes the pump handle from its place on the side of the dispenser, this action activates a switch that starts the dispenser operation. (In some cases the switch is spring-loaded and activates automatically; in others, the customer must raise a small lever manually to begin the process.) At that point, the customer simply inserts the nozzle into the car's gas tank and pulls the lever. Stopping the flow of gas is just as simple -- the customer need only release the lever to cut off the stream of fuel.
      But what if the tank fills unexpectedly to the brim and the gasoline threatens to overflow? As anyone who's ever operated a gas pump knows, the pump will switch off automatically. But how does the pump know when to stop pumping? 


                             XXX  .  V000000 WATER PUMP PRESSURE CONTROL SWITCH


      information about water pump pressure control switch diagnosis, repair, or installation.
      Cla-Val PC-1 Pump Control Panel with status indicator lights, Cla-Val Inc., www.cla-val.com
      • Recommended: Water pump relay switch with built-in low pressure or overload cut-off features. Larger horsepower well pumps, usually submersible models, are switched on and off by a heavy-duty pump relay switch that is itself operated by the water pump pressure control switch described above.

        Among water pump relays are more sophisticated models that include sensors that can shut off the pump it it's pumping air. These pump relay controls usually work by monitoring the current draw of the pump, or in some cases the pump motor temperature, or actual water flow. For example

        • Pumptec pump protection device, Franklin Electric, 400 E. Spring St. Bluffton, IN 46714 Tel: 260-824-2900 Fax: 260-824-2909 www.franklin-electric.com. The company offers a submersible pump service hotline for their products: 800-348-2420. [Please don't embarrass us and yourself by calling Franklin to ask about other pump brands.] The company's description of their PumpTec controller includes:
          Pumptec is a microcomputer based pump protection device that continuously monitors motor load and power line conditions to provide protection against dry well conditions, waterlogged tanks, and abnormal line voltage conditions. Indicator lights provide complete system status, which can be easily viewed without removing the cover.
          Pumptec interrupts power to the motor whenever the motor load drops below a preset level or the load drops quickly. Pumptec is optimized to work with Franklin 2- & 3-wire single phase motors from 1/3 to 1.5 HP. An underload (dry well) adjustment is provided to address unusual situations.

          The PumpTec controller uses three indicator lights to indicate power, electrical load, and voltage levels. An "underload" indication can indicate that the well is dry while an "overload" indication typically means that there is a problem with the pump motor, causing it to draw excessive current.
      PumpStop protection switch - www.pumpstopnow.com PumpStop protection switch - www.pumpstopnow.com
        • PumpStop universal pump protection switch [shown above in a photo & wiring sketch from the company's website] for jet pumps & centrifugal pumps, protects against loss of pump prime, stuck or failed pressure control switch, broken valves, stuck relays, loss of water in the well itself, user error, check valve failure. The switch is simply wired into the pump power line input tothe pressure control switch, in series.


          Pump overheat damage is caused when water stops flowing and the pump continues to run. This causes the water in the pump to get very hot resulting in total system failure. The POP 120 shuts off the pump before overheat damage occurs, keeping the pump system safe until repairs can be made.
          Contact: PumpStop, General Contracting Services P.O. Box 631 Cocoa Beach, Fl. 32932 321-333-9887 Tel: 321-333-9887, Website: www.overheatprotection.com

          The instructions for installing this device call for interrupting either of the two 120V input or "hot" wires to a 240V pump pressure control switch to wire the PumpStop in series. Indeed switcing one-leg of a 240V circuit should turn off the pump.

          Watch out: safety hazards remain when you power off only one leg of a 240V circuit if someone working on the circuit thinks that all power is off when in fact one leg remains live or "hot".

          You might check with your pump manufacturer and with the manufacturer of any other controls that may be wired in the circuit, asking about the effects of interrupting only one of the power wires to the pump.

          We have on occasion heard from readers who got into trouble interrupting one leg of the two 120V legs that typically power a 120V motor or circuit, depending on how those two legs were used. A reader asserted that on loss of one leg of the 240V pump circuit, their particular pump continued to run but at a slow speed. For example when a remaining 120V leg of a circuit is left "hot" there may be current leak or safety risks remaining at the wired device.

          Generally a pump or other electric motor won't be damaged if there is full voltage or no voltage provided to the device. Reduced voltage can cause damage.
        
     
                              XXX  .  V0000000   DC Inverter air-to-water heat pumps S-THERM 
     

    DC Inverter air-to-water heat pumps S-THERM

    Air-to-water heat pump takes heat from the outdoor air and transfers it to the water which is then used for heating of a house or of domestic hot water. Modern heat pump can take heat from air even in low ambient temperatures, so they can work almost all year-round.
    S-THERM heat pump is designed for providing hot water for heating in the winter but it can also provide cold water for cooling in summer. If you use fan-coil units, this heat pump can be used for cooling and heating. There is no need for independent air-conditioning unit.

    Why to choose our heat pump

    Because our S-THERM heat pumps adopt DC inverter technology, the compressor can adapt its power to meet actual requirements. This prevents from overheating the house, mainly if outdoor temperatures are around 0°C. Inverter technology is the main advantage over heat pumps with an on/off compressor which runs at their maximum capacity all the time.
    The compressor is located in the outdoor unit, so indoor unit is as quiet as possible. A water pump is the only one moving component in the indoor unit. There are two fans in the outdoor unit. Due to this, fans can run at lower speed and noise from outdoor unit is lower.

    Features

    • Panasonic rotary compressor with DC Inverter
    • Wilo water pump
    • Integrated expansion tank and safety valve
    • Electronic expansion valve
    • Refrigerant R410A
    • Integrated 6 kW electric heater
    • Outflow water temperature 55°C

    Complex control system

    Not only the refrigerant circuit, but also the heating system can be both controlled by control system of the heat pump. A user can activate weather compensation mode, which accommodates the outlet water temperature according to the outdoor temperature. When outdoor temperatures are higher, the heat pump will provide lower water temperature and will work with better COP.
    In the summer, the control system can close valves to radiator or floor-heating and use only fan coil units for cooling. Therefore, these units can provide comfort all year-round, in winter and in summer.

    Advantages of products

    Indoor unit
    • Wall mounted - it takes less space than stationary units
    • Integrated expansion tank and safety valve
    • User-friendly interface
    • Backlighted display
    • 6 kW integrated e-heater
    • Very quiet operation
    • Automatic air vent valve
    • Easy installation
    Outdoor unit
    • Optimized grille of the fan for better efficiency
    • Connection valves inside the unit - nicer, undisturbed appearance of the unit
    • Large surface of the evaporator for more effective heat transfer
    • Insulated components to prevent from frosting
    • Low noise
    The device contains fluorinated greenhouse gases covered by the Kyoto Protocol. Used refrigerant R410A (50% HFC-32, 50% HFC-125), GWP 2088, environmentally friendly.
     
       
     
     
                                               XXX  .  V0000000  Air source heat pumps 
     

    Air source heat pumps (ASHPs) absorb heat from the outside air. This heat can then be used to heat radiators, under floor heating systems, or warm air convectors and hot water in your home.

    Different from a ground source heat pump, an air source heat pump extracts heat from the outside air in the same way that a fridge extracts heat from its inside. It can get heat from the air even when the temperature is as low as -15° C. Heat pumps have some impact on the environment as they need electricity to run, but the heat they extract from the ground, air, or water is constantly being renewed naturally.

    The benefits of air source heat pumps

    • Lower fuel bills, especially if you are replacing conventional electric heating
    • potential income through the UK government’s Renewable Heat Incentive (RHI)
    • lower home carbon emissions, depending on which fuel you are replacing
    • no fuel deliveries needed
    • can heat your home as well as your water
    • minimal maintenance required
    • can be easier to install than a ground source heat pump.
    Unlike gas and oil boilers, heat pumps deliver heat at lower temperatures over much longer periods. During the winter they may need to be on constantly to heat your home efficiently. You will also notice that radiators won't feel as hot to the touch as they might do when you are using a gas or oil boiler.
    View case studies and examples of homeowners who live in Scotland who have installed an air source heat pump.

    How do air source heat pumps work?

    Heat from the air is absorbed at low temperature into a fluid. This fluid then passes through a compressor where its temperature is increased, and transfers its higher temperature heat to the heating and hot water circuits of the house. There are two main types of air source heat pump systems.
    1. Air-to-water
      An air-to-water system distributes heat via your wet central heating system. Heat pumps work much more efficiently at a lower temperature than a standard boiler system would. This makes them more suitable for underfloor heating systems or larger radiators, which give out heat at lower temperatures over longer periods of time.
       
    2. Air-to-air
      An air-to-air system produces warm air which is circulated by fans to heat your home. They are unlikely to provide you with hot water as well.

    Is an air source heat pump suitable for me?

    To tell if an air source heat pump is right for you, there are a few key questions to consider:
    • Do you have somewhere to put it? You'll need a place outside your home where a unit can be fitted to a wall or placed on the ground. It will need plenty of space around it to get a good flow of air. A sunny wall is ideal.
    • Is your home well insulated? Since air source heat pumps work best when producing heat at a lower temperature than traditional boilers, it's essential that your home is well insulated and draught-proofed for the heating system to be most efficient.
    • What fuel will you be replacing? The system will pay for itself much more quickly if it's replacing an electricity or coal heating system. Heat pumps may not be the best option for homes using mains gas.
    • What type of heating system will you use? Air source heat pumps can perform better with under floor heating systems or warm air heating than with radiator-based systems because of the lower water temperatures required.
    • Is the system intended for a new development? Combining the installation with other building work can reduce the cost of installing the system.
    You may also want to consider ground source heat pumps, which use pipes buried in the ground outside to extract heat. If you live in Scotland, we recommend using our Renewables Selector tool to find out which means of generating energy might work best for you.
    Costs, savings and financial support

    Costs

    Installing a typical system costs around £6,000 to £8,000. Running costs will vary depending on a number of factors including the size of your home, how well insulated it is and what room temperatures you are aiming to achieve.

    Savings

    How much you can save will depend on what system you use now, as well as what you are replacing it with. Your savings will be affected by:
    • Your heat distribution system. If you have the opportunity, under floor heating can be more efficient than radiators because the water doesn’t need to be so hot. If under floor heating isn’t possible, use the largest radiators you can. Your installer should be able to advise on this.
    • Your fuel costs. You will still have to pay fuel bills with a heat pump because it is powered by electricity, but you will save on the fuel you are replacing.
    • Your old heating system. If your old heating system was inefficient, you are more likely to see lower running costs with a new heat pump.
    • Water heating. If the heat pump is providing hot water then this could limit the overall efficiency. You might want to consider solar water heating to provide hot water in the summer and help keep your heat pump efficiency up.
    • Using controls. Learn how to control the system so you can get the most out of it. You will probably need to set the heating to come on for longer hours, but you might be able to set the thermostat lower and still feel comfortable. Your installer should explain to you how to control the system so you can use it most effectively.

    Potential annual savings of installing a standard air source heat pump in an average sized, four-bedroom detached home:

    England, Scotland and Wales

    Existing system

    Fuel bill saving

    (per year)

    Annual RHI payments

    (installations between

    20 September to 31 December 2017)

    Carbon savings

    (per year)
    Old (G-rated) gas boiler
    New (A-rated) gas boiler
    £455 - £485
    An increase of £10 - £15
    £1,140 - £1,235
    3,000 - 3,300 kg
    900 kg
    Old electric storage heaters
    New electric storage heaters
    £735 - £820
    £410 - £445
    5,500 - 6,100 kg
    3,800 - 4,100 kg
    Old (G-rated) oil boiler
    New (A-rated) oil boiler
    £290 - £315
    An increase of £155 - £165
    4,900 - 5,400 kg
    1,900 - 2,100 kg
    Old (G-rated) LPG boiler
    New (A-rated) LPG boiler
    £1,000 - £1,090
    £290 - £315
    3,900 - 4,200 kg
    1,400 - 1,500 kg
    Coal£415 - £4656,700 - 7,300 kg
    Figures are based fuel prices as of April 2017.
    See the domestic Renewable Heat Incentive page for the latest information and proposed changes to the RHI scheme. 

    Northern Ireland 

    Existing system

    Fuel bill saving

    (per year)

    Carbon savings

    (per year)

    Old (G-rated) gas boiler
    New (A-rated) gas boiler
    £315 - £345
    An increase of £135 - £145
    3,000 - 3,300 kg
    900 kg
    Old electric storage heaters
    New electric storage heaters
    £575 - £650
    £270 - £295
    5,500 - 6,100 kg
    3,800 - 4,100 kg
    Old (G-rated) oil boiler
    New (A-rated) oil boiler
    £170 - £185
    An increase of £230 - £250
    4,900 - 5,400 kg
    1,900 - 2,100 kg
    Old (G-rated) LPG boiler
    New (A-rated) LPG boiler
    £1,280 - £1,390
    £455 - £490
    3,900 - 4,200 kg
    1,400 - 1,500 kg
    Coal
    £245 - £275
    6,700 - 7,300 kg
    Figures are based on fuel prices as of April 2017.
    Find out more about how we made these calculations.

    Note: The Renewable Heat Incentive is no longer available in Northern Ireland.

    Financial support

    You may be eligible to receive payments for the heat you generate using a heat pump through the UK Government’s Renewable Heat Incentive (RHI).
    Domestic RHI is no longer available in Northern Ireland - details of the previous scheme can be viewed at NI Direct.

    Maintenance

    Heat pump systems typically come with a warranty of two to three years. Workmanship warranties for heat pumps can last for up to 10 years, for example through QANW (Quality Assured National Warranties). Many manufacturers also offer options for warranty extensions for a fee. You can expect them to operate for 20 years or more, however they do require regular scheduled maintenance. A yearly check by you and a more detailed check by a professional installer every three to five years should be sufficient.
    The installer should leave written details of any maintenance checks you should undertake to ensure everything is working properly. Consult with your supplier for exact maintenance requirements before you commit to installing a heat pump. You are likely to be advised to carry out a yearly check that the air inlet grill and evaporator are free of leaves or other debris. Any plants that have started to grow near the heat pump unit will also need to be removed.
    You may also be advised by your installer to check the central heating pressure gauge in your house from time to time. If so, you should be shown how to do this. To prevent the heat pump from freezing in cold winter weather anti-freeze is used. Levels of anti-freeze and its concentration is one of the things that a professional installer will check when he comes to service your heat pump. If your heat pump has external refrigeration pipes, (very unusual for a domestic system) these will need to be serviced annually by a refrigeration engineer.

    Planning permission

    Before starting, the developer must apply to the relevant planning authority for a determination as to whether the prior approval of the authority will be required for the siting and external appearance of the air source heat pump. The application needs to be accompanied by a range of other information and several other conditions apply.



                                




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