Hydraulic accumulator: device and principle of operation of a hydraulic tank in a water supply system
To ensure stable operation of the water supply system, you should find out what a hydraulic accumulator is.This useful device is necessary to automate the operation of an independent water supply system.
It also allows you to significantly extend the life of the pump and protect equipment from water hammer.
In this material we will talk about the design and principles of operation of hydraulic accumulators, and also provide recommendations for installing equipment.
The content of the article:
Design and principle of operation
What distinguishes a hydraulic accumulator from a conventional storage device is a more complex device that significantly expands its functionality.
It consists of:
- metal case;
- inner membrane;
- nipple;
- water pipe.
The membrane divides the container into two parts, one is intended for water, and the second is pumped with air or inert gas. As a result, the liquid inside the device is under a certain pressure. This allows you to regulate the water pressure in the system.
Anyone who has at least once encountered the problem of low pressure in the system can tell you why a hydraulic accumulator is needed. Sometimes the problem is solved using booster pump, but GA is a more efficient option.
It is installed in the system after the pump on an external or internal water supply; the specific scheme depends on the characteristics of the system. Water enters the container and accumulates there, while thanks to the membrane inside, the pressure necessary for the normal operation of an autonomous water supply with trouble-free water supply to the taps is created.
A conventional storage tank does not guarantee suitable pressure characteristics for a water supply system, since the pressure is created only due to the difference in height between the water intake point and the water container. But with GA there is no need to raise the tank to the attic or overpass, since you can pump in air to create the desired pressure.
Modern technology, for example, an automatic machine, hydromassage, jacuzzi, dishwasher, can only function when standard pressure values in the water supply network. And it’s more convenient to take a regular shower when the flow of water is strong enough, rather than flowing in a weak trickle.
The hydraulic accumulator must be used in conjunction with a pressure switch, which controls the pump that supplies water from a well, well, etc., and a pressure gauge designed to control and monitor the operating parameters of an independent water supply.
The relay is configured so that when the user-selected pressure is reached, the pump turns on and off. When a sufficient amount of water has filled the accumulator and the pressure reaches the maximum set point, the pump will turn off. This indicator is called cut-out pressure for obvious reasons.
As water is used, the pressure in the tank gradually decreases. When it reaches the minimum set value (this is the so-called switch-on pressure), the pump starts working. Water enters the container, the pressure rises, reaches a limit, after which the pump turns off.
Then the water decreases from the tank again when the owners of the house open the tap, the pressure drops, the relay starts the pump, etc.If we exclude the GA and relay from this chain, the pumping equipment will turn on every time the tap is opened. Such use of expensive equipment is irrational, since its service life is limited to a certain number of on-off switches.
In addition, the pump supplies water rapidly, which can result in such a phenomenon as water hammer. For a water supply system, such loads are undesirable; they can damage the pipes. And the hydraulic accumulator is a durable device that will become a buffer and protect the system from unwanted influences.
Finally, the hydraulic tank allows you to create a certain supply of water. Even in the absence of electricity, it will be possible to use water stored in the HA for some time. Of course, this is not as large a reserve as in a drive, but it can also be very useful.
What types of hydraulic accumulators are there?
There are vertical and horizontal devices, they are installed in different ways. Typically, tanks with a capacity of up to 50 liters are placed horizontally, and larger ones - vertically, so as not to take up much space. This does not affect efficiency. You can choose a model that will be more convenient to use and suitable for the place where it will be installed.
In vertical and horizontal models, a nipple - an air valve - is provided to remove air from the part into which air or gas is pumped. It's very easy to use.
It is located on all types of hydraulic tanks on the side opposite to the installation of the flange intended for connecting equipment to the water supply.
The color of the container is usually blue or blue, in contrast to the red expansion tanks for heating. They are not interchangeable; different materials are used to make the membrane. Food-grade rubber is used in “cold” hydraulic tanks.
In addition, blue accumulators can withstand higher pressure than heating and hot water devices. You cannot use such containers for other purposes; they will quickly fail.
In vertically oriented HAs, water is supplied from below, and excess air is removed, if necessary, from above, bleeding it through the nipple. In horizontal versions, both water supply and air bleed are done from the side.
The threaded connection for connecting to the water supply is always the same size, it is 1 1/2 inches. The thread for connecting the membrane can be internal or external. Their dimensions are also unified, the internal thread is standard 1/2 inch, the external thread is 3/4 inch. This is an important point, since for a reliable connection it is necessary that the dimensions of the nozzle and the water pipe match.
If you plan to organize an independent water supply system, you need to know how a conventional water accumulator works. You should immediately decide on options for connecting to the water supply and methods for removing air if the pressure exceeds the standard value, as well as connection diagrams to the system.
It should be remembered that they were initially designed to suit the conditions of the country where they were produced, and they do not always coincide with local realities. Operating conditions may be too difficult for Western models, so it makes sense to look for an option from a domestic manufacturer, which may be more attractive in cost.
Recommendations for installation and operation
Installing a hydraulic tank is easy; it is simply connected to the water supply system after the pump. Before entering the device, you need to install a good filter to clean the water from impurities. They can accumulate inside and damage the membrane.
You need to choose the right place for installation. The GA should be placed where one can freely approach to inspect the device and maintain it. Over time, the device may need to be repaired, so it doesn’t hurt to think in advance about the procedure for dismantling it and the difficulties that may arise at this time.
It is very important that the dimensions of the pipe and the water pipe match. This will avoid hydraulic losses due to narrowing of the route in some area. The use of adapters is acceptable, but not recommended. As water flows in and out, the membrane tank may vibrate.
It is recommended to attach it to the base using shock-absorbing pads. Connection to the water supply is made with a flexible liner.You should make sure that the device is correctly aligned horizontally and vertically; distortions are not allowed.
It is necessary to take care in advance about the possibility of disconnecting the HA from the water supply so that you do not have to completely drain the water from the system. This requirement is met by installing a conventional shut-off valve. For small containers with a capacity of up to 10 liters, which do not have a nipple, it is also necessary to provide for the installation of a drain valve.
You can read more about how to connect a hydraulic accumulator to a water supply system in this material.
Maintenance of the hydraulic tank comes down to a careful inspection of the housing and monitoring the pressure in the air compartment. Sometimes you need to pump up the air or bleed it to restore the correct performance. Typically the pressure should be about two atmospheres or slightly less. In addition, the air that has accumulated behind the membrane in the compartment where the water is stored should be removed.
Sometimes you can even install an automatic air vent here. If there is no hole for this procedure, you need to disconnect the HA from the water supply and completely empty it through the drain tap. The air will come out of the container along with the water. Then you just have to turn on the pump again so that water starts flowing into the tank again.
Speaking about how a membrane accumulator works, it is worth noting that the most common failure in a hydraulic accumulator is a membrane rupture. This elastic element is subject to constant tension and compression, and therefore fails over time.
Here are the signs that the membrane has ruptured:
- water comes from the tap in sharp bursts;
- the pressure gauge needle “jumps”;
- After the contents of the “air” compartment are completely bled, water flows out of the nipple.
The last point allows you to accurately determine whether the problem is really with the membrane. If water does not flow out of the nipple, and water enters the system poorly, most likely the housing is depressurized. You need to carefully examine it, find and repair the cracks.
Replacing the membrane is not difficult, but you need to select exactly the same element as the damaged one, since it is designed specifically for this particular HA.
To carry out repairs, you need:
- Disconnect the device from the water supply system.
- Drain the water, bleed the air.
- Unscrew the mounting screws.
- Remove the damaged membrane.
- Install the correct element.
- Secure it with screws.
- Install the GA in place and connect it to the system.
The most difficult part of this procedure is tightening the screws. It should be uniform, so it is recommended to twist them, making one turn on each element in turn. This tactic will allow you to properly secure the membrane to the body and prevent its edge from sliding inward.
Some inexperienced craftsmen, in an effort to improve the quality of the connection, apply sealant to the edge of the membrane. This should not be done, since the composition can destroy the rubber and cause the opposite effect.
Conclusions and useful video on the topic
Design and principle of operation of the GA:
For an autonomous water supply system, a hydraulic accumulator is a useful equipment that provides automatic water intake and turning on/off the pump. Such a device will improve the quality of water supply and prevent breakdown of technical devices.
After studying the material, do you have any questions? You can ask them in the comments section, and we will try to give them a very clear answer.
My house is connected to the central water supply, but the pressure in it is such that it is only enough for the first floor. On the second, where we have a shower cabin with hydromassage, the pressure is only 0.5 atmospheres. Therefore, the hydromassage nozzle, which requires at least 1.5 atm, does not work. I had to install a small pumping station with a 24-liter hydraulic accumulator.
In addition, I also installed a tank for 1 cubic meter of water, from which the hydrophore already takes water and supplies it to all consumer points in the house. Now the pressure on the second floor is excellent, about 2 atm. And I also have a supply of water for every firefighter.
I'm having some problems connecting the accumulator. I have it with two outputs - top and bottom, and in the connection diagram that I found on the Internet, the liner is connected only from the bottom. How to connect it correctly? Or is the top outlet even for the pressure gauge? A friend says that a safety valve needs to be installed on top, but he also doesn’t have much experience. I feel like I’m still going to suffer with this GA.
The top terminal on the accumulator is for a pressure gauge and other things. You can put a five-way fitting there and screw on a pressure gauge, pressure switch, automatic air vent, etc. If there is a free exit, it must be plugged.
Good afternoon.
The information is useful, but I would like to know what the initial pressure should be in the hydraulic tank before putting the system into operation, after assembling all the components?