Showing posts with label Prevent. Show all posts
Showing posts with label Prevent. Show all posts

Sunday, November 20, 2011

Electric Fuel Pumps - Design, Work and Faults

!: Electric Fuel Pumps - Design, Work and Faults

Electric fuel pump is used in modern internal combustion engines to supply fuel from the fuel tank to the injectors. The pump should deliver fuel under high pressure, so that the nozzle can spray it into the engine. For the proper engine operation fuel pressure should be within allowed specifications for a given engine. Too low-pressure can lead to "fuel starvation" engine misfire, excessive vibration or stop the engine under load. Too much pressure causes uneven engine running too rich mixture, and excessive pollution.

Electric fuel pumps are usually installed in fuel tank (intake), although some can be installed outside. Some cars may be equipped with two pumps (one pump inside the tank and the main pump on the outside). The location of the pump in the fuel tank helps mute the buzzing noise of pump's electric motor. Submersion into the fuel helps lubricate and cool the pump's engine. Driving with fuel tank filled with less than ¼ of its volume can shorten the life of the pump and cause rapid overheating. It also increases risk of pump left without of gas during rapid acceleration or deceleration.

The pump is usually part of a module that also includes a float that carries electrical signals to the level indicator, located on the dashboard. If the fuel pump needs replacing, it can be replaced separately or the complete module assembly (it is expensive, but much easier).

Different electric fuel pumps have different designs. Some older designs used to use forced displacement of the circulation pump chamber. This type of pump can produce very high pressure and constant flow. But at the outlet of the fuel pump has been strong pressure fluctuations, so often in the gas line after the pump was installed damper to reduce the amplitude of pulsation of gas pressure. Circulating chamber can also be installed outside the tank and used with the second low-pressure pump installed in the fuel tank.

There is another type of fuel pump - "rotor-type". This design is similar to design of the oil pump and uses the offset rotor to push the fuel through the pump. Another variation of the roller pump - "vane-type". The blades are used instead of rollers to push the gas through the pump. Most modern cars use a pump turbine. Blades of the impeller push gas through the pump. Turbine type pumps do not produce the pressure fluctuations these types are less complicated to manufacture and more reliable in operation. It is possible to replace a fuel pump by not original unit. In this case fuel pump's output should be within original specifications and as consumption the same as the original one. Use of an improper specs can cause deterioration of performance of the car.

How does electric fuel pump work?

When the ignition, the electronic control unit excites the relay, which supplies voltage to fuel pump, its motor starts to rotate, and within a few seconds it creates necessary gas pressure. Fuel feeds into the inlet pump through a mesh filter to delay the rust and dirt. Outlet of the pump the gas passes through the check valve, single acting (valve maintains a residual pressure in the system, when pump does not work) and feeds to the engine through the fuel line and filter. The fuel filter catches any rust, dirt and other solid contaminants that have passed through the pump to prevent the penetration of these particles in the injectors.

Further, the gas enters the fuel rail, located on the engine and from the rail to each injector. Fuel pressure regulator, located on the ramp, maintains the fuel pressure and throws any excess back to the tank. Start the engine and the electric fuel pump starts to operate continuously and to keep pumping gas until the engine is running. If the engine stops, then the electronic control unit receives a signal from the sensor and the crankshaft ECU will turn off the pump.

A lot of cars (especially Fords) have an inertial emergency switch which disables the fuel pump in the event of an accident. It is envisaged to reduce the risk of fire when the fuel line is damaged. To return the emergency transmitter to its original state - press the reset button on the sensor. On older cars pumps operated at a constant speed. In newer designs pump's speed is being controlled by the electronic control unit in order to precisely match allowed specifications.

Fuel pump failure

The fuel pump can fail for several reasons: - Due to the presence of contaminants inside the fuel tank (dirt or rust); - When driving out of gas; - As a result of overheating (in constant motion with a low level of gas in tank); - Low voltage (problems with electrical wiring); - As a result of overloading (for a clogged fuel filter excessive resistance of the filter element can cause an overload of electric motor pump). The harder the conditions of the fuel pump, the more power is required for its operation. Electric fuel pump often fails without any warning. You may drive your car without a trouble, and within a minute the pump fails, the engine just stalls and the car gets up in the middle of the road. Or in the morning you are going to start the car but the engine just will not start.

By what signs can one predict the damage the fuel pump? One way is to listen to the noise of the pump when the ignition is on. Complete absence of noise indicates that it is not working. It can be caused by a malfunction of the pump, pump relay malfunction, the fuse or the lack of voltage. On most cars when fuel pump fails you wouldn't see usual Check Engine light on. Most modern engines equipped with the union to check the fuel pressure on the ramp nozzles. Connecting fuel pressure gauge to the fitting check valve will quickly show whether the pump produces pressure or not. On engines without pressure test union, to measure pressure can be done by connecting directly to the fuel line at the junction of the ramp. If the gauge indicates zero - the pump does not work. If the pressure is less than nominal, it will be necessary to carry out further diagnosis to identify the causes of low fuel pressure.


Electric Fuel Pumps - Design, Work and Faults

!: Acoustic Research Ar3A

Tuesday, October 18, 2011

Prevent Pinhole and Slab Leaks and Conserve Energy by Controlling Your Hot Water Circulating Pump

!: Prevent Pinhole and Slab Leaks and Conserve Energy by Controlling Your Hot Water Circulating Pump

If you have had 1 leak, more will surely follow - you can do something about it before further damage is done and additional money is wasted.

Circulating hot water is the fastest way to wear out your pipes. In fact 90% of all pinhole leaks and slab leaks happen in hot water lines for the following reasons:

1. Chemicals in water are corrosive

2. Chemicals in water when heated are even more corrosive

3. Chemicals in water when heated and circulated through copper pipes that bend around corners and turn up walls and curve around electrical conduit and sewer pipes and are reduced in size as water passes through a building is extremely corrosive

In order to understand the solution it is helpful to know what causes the problem. With a little insight into how domestic hot water recirculation lines or recirc loops are built and how they work we can see that the answer is as easy as flipping a switch.

Apartments, hotels and larger homes have recirc loops designed to move hot water to the farthest fixture from the boiler or water heater in a reasonable amount of time. Each loop has a pump pushing water through a copper pipe 24 hours a day, 7 days a week. Each loop has multiple joints and fittings that obstruct the flow of water. Gate or ball valves and flapper checks and expansion tanks and whatever else the plumber had on his truck the day he built the line create disturbances in the flow path.

Water likes to flow in a nice straight line with no obstructions. This is called laminar flow - nice and smooth. Anything in the flow path can disrupt the flow and cause an eddy to form. Eddies are the bad boys, the unwanted visitor, the black sheep of the family.

Create a little friction, add in some turbulence and the next thing you know you have a leak.

As your reading this please keep in mind there are things you can do to reduce or even eliminate leaks. They are relatively inexpensive and I'll tell you what they are in a minute.

When water pipes leak many things can happen - none of which are any good. Pinhole and slab leaks, mold, wasted water, wasted energy, property damage, resident/guest complaints and inconvenience all mean one thing.

It cost you time and money.

The only question left is how much? Please refer to Table 1 for an idea of how much a leak can cost.

Table 1: The Cost of a Leak

1 0 You caught the leak early and it wasn't buried in a wall or under a slab

2 ,000 The leak was in a wall and you caught it early and it was relatively accessible after tearing out some drywall

3 ,000 Same as above except you didn't catch it early and mold and light structural damage had occurred

4 ,000 The leak was underneath a concrete slab but you were able to pinpoint the exact location

5 ,000 Same as above except you had to chase the leak into other rooms

6 0,000 + The leak went unnoticed until someone got sick and you got sued

So there is the doom and gloom. What's the solution?

Good question. The answer is there are a number of things you can do. As you go through my list keep in mind that people only use hot water 15% to 20% of the time (based on a study by the California Energy Commission).

First, check your water pressure. 40 psi is high enough for most 1 or 2 story buildings. Be sure to check it in several places to find the lowest pressure in the building. Typically that would be the point furthest from the water meter. If you don't have a pressure regulator, put one in.

When implementing this strategy do it in stages. Drop the pressure by 5 psi at a time and wait to see if you have any complaints. Shower heads and aerators already restrict flow to 2.5 gpm or less. Newer fixtures like the Evolve line of low flow shower heads have pressure compensating technology built into them and work just as well at low pressure as they do at high pressure.

Second, turn off the pump when no one is using hot water. That's right. I said turn off the pump. As I mentioned earlier people only use hot water 15% to 20% of the time. The pump only needs to be on when people need water.

There are 3 methods of implementing this strategy:

1. The Manual Method

2. The Guessing Method

3. The Automated Method

Manual Method

Have someone go to the switch and turn on the pump when you need hot water and turn it off when you are done. Might be practical for a single family home (certainly not convenient) but impossible in an apartment or hotel.

The Guessing Method

Plug your pump into a timer and guess when hot water will be needed. This may be a practical solution if the number of people living in the house or apartment or with a limited number of guests in a hotel and everyone has the same predictable need for hot water. Unfortunately when hot water is needed during an off period the timer gets disabled and never turned back on.

The Automated Method

Think about your recirculation line as a closed loop. When there is no demand for hot water, no water enters or leaves the system. When a hot water faucet is turned on there is a "leak" in the system.

When water leaves the system more water is added from the city water line through a cold water make-up line (this is the technical name for the copper pipe that brings cold water to your water heater).

If a flow sensor is placed in the cold water make-up line, any indication of water movement would mean someone is using hot water.

If the sensor sensed a demand (i.e., someone turned on a hot water faucet) it could turn on the pump. The demand would be met and the pump could be turned off automatically when the demand ended.

That is precisely how an On-Demand Intelligent Pump Controller works. The pump is only on when there is a demand.

As it turns out, there are many benefits to automating your recirc pumps operation:

o Drastically reduces pinhole leaks and slab leaks - if the hot water is not moving, it is much less corrosive

o Energy is conserved - since people only use hot water 15% to 20% of the time, the pump will be off 80% to 85% of the time. That means the recirculation line isn't full of hot water and no energy is being lost. California Energy Commission studies indicate 37% less energy is consumed when an On-Demand Controller is installed.

Note: A sufficiently high speed pump is required (2,200 rpm or faster) to implement this strategy. If you have a high speed pump you will only need an ARC 100 Controller. If not you will need a full system including a high speed pump.

In conclusion, cut your risks, lower your losses, reduce your energy bill and extend the life of you pipes and water heater or boiler by turning off you recirc pump with an ARC 100 Pump Controller.

Contact me directly at the email address below to find out if this solution will work for you or what other options you might have. To purchase the ARC 100 Pump Controller click on the link below.

Do it now and sleep better tonight knowing that one of your biggest headaches just got cured.


Prevent Pinhole and Slab Leaks and Conserve Energy by Controlling Your Hot Water Circulating Pump

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