Hydraulic accumulator for water supply systems: device, membrane replacement

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A well-designed and properly installed water supply system can operate smoothly for years, much depends on the correct choice of components. This review will focus on hydroaccumulators, their principle of operation, installation options, repair and maintenance..

Hydraulic accumulator for water supply systems: device, membrane replacement

Why does a pumping station need a hydraulic accumulator

The main function of the pumping station is to continuously supply the consumer with water, while ensuring the required operating pressure range both for the points of water intake and for the operation of household appliances. Unfortunately, there is no effective way to tell the pump when the tap is open, so the only thing that the automation can focus on is the pressure drop in the system when a certain amount of water has flowed out of it..

Another difficulty of work is the physical properties of a liquid, which practically does not compress, in contrast to gases. Gaining the required pressure is not an easy task, because under normal conditions this is possible only by expanding pipes and other channels filled with water.

Hydraulic accumulator for water supply systems: device, membrane replacement

The hydraulic accumulator (HA) is connected by a tie-in at an arbitrary point of the water supply system between the pump and the consumer, thereby increasing its displacement. Its device takes over the main volume of the pumped water and provides a smooth increase in pressure in the period between turning the pump on and off..

Advantage over pressure regulator

From a purely technical point of view, a water supply system with an automated pumping station can operate without a storage device. If the pipeline is made of polymer materials, they can expand sufficiently to accommodate an extra liter and a half of water to create the required pressure. But this mode of operation is associated with a number of non-obvious risks..

Electronic pressure switch Example of an electronic pressure switch

Firstly, turning on and off the pump does not happen instantly, there is always a risk of malfunctions. From this, the phenomenon of inertial transfer occurs when the pump “starts” too early or does not have time to shut down in time, which causes a dynamic load on the water supply connections, flexible hoses and shut-off valves.

The highly publicized electronic pressure regulators determine the current pressure in the system quite accurately. And yet, the displacement of the pipeline is too small to ensure uninterrupted operation: the electronics sin by turning on the emergency mode due to excessive pressure, while the contact group is triggered at a high frequency, which does not add longevity to it or the pumping equipment.

Mechanical pressure switchMechanical pressure switch. 1. Spring for setting the upper limit of relay operation. 2. Spring for adjusting the working pressure range. 3. Contact group

Device and principle of operation

The main feature of the accumulator is the absence of rigid walls in the tank filled with water. Instead, an elastic rubber “bulb” is used, which, in turn, is located in a rigid and sealed body of the device, filled with air under some pressure.

Normally, the bulb is filled to such an extent that it compresses the air in the housing to create a working pressure that is equivalent to virtually any point in the water supply. The relay controlling the pump in this mode is open, because the pressure is correct, and there are no reasons for water supply.

Hydraulic accumulator device

When any draw-off point is opened, water flows out of the system and from the reservoir in particular. Before the pressure in the accumulator drops to the minimum value, and the relay is triggered with the subsequent turning on of the pump, a lot of water can flow out. After switching on the pump, a sharp jump in pressure occurs in the supply line, but this is compensated by a flexible reservoir and an air envelope. Accordingly, a short time will also pass between the moment of closing the drawdown and stopping the pump..

With the use of a hydraulic accumulator, a whole layer of problems associated with water hammer and “over-pumping” of the system disappears: the air cushion acts as a damper, smoothing out sharp fluctuations and reducing the load on the pipeline elements.

Installation of a hydraulic accumulator

As already mentioned, the place where the accumulator is included in the system can be arbitrary. Therefore, it should be installed where the best conditions for the equipment are observed: high enough temperature so that the water does not freeze inside, and not very high humidity so that the metal body and fittings are less corroded. To eliminate unnecessary noise, the drive together with the pumping station is usually taken out of the living area into a technical well..

Hydraulic accumulator for water supply systems: device, membrane replacement

An ordinary battery, not equipped with a pump and an automation group, has only one output. A manifold assembly with three or four additional leads with an external or internal thread is packed to it on a Teflon tape. Some models, however, come complete with a manifold and do not need to pack..

One of the taps, usually the bottom one, is designed to connect the supply line through a check valve. The pump itself can stand next to the storage tank or be lowered into the well – this does not significantly affect the operation of the system.

Hydraulic accumulator for water supply systems: device, membrane replacement

A line is connected to the second free outlet, which distributes water to consumption points. The third branch is designed to install a hydraulic pressure gauge, which monitors the working pressure in the system. Sometimes this outlet has a slightly smaller internal thread for mounting without using adapters..

The fourth free outlet is needed to connect a pressure switch to the system, but if the pump is controlled by an electronic regulator, it is connected in series to the supply line. If there is a danger of airing the system, the pressure switch is installed through a special tee, one of the outputs of which has a built-in automatic air relief valve.

Typical malfunctions and methods of elimination

Hydraulic accumulators, as a rule, are very unpretentious in maintenance and have a fairly long service life – about 10 years. But unpleasant incidents and malfunctions still happen.

The most common option is when the frequency of turning on and off the pump, as it were, suggests that the accumulator cannot cope with the function of a smooth set and pressure release. You can find out the specific reason for this behavior only by unscrewing a few bolts and removing the technical flange into which the inlet pipe is cut.

Hydraulic accumulator for water supply systems: device, membrane replacement

If the drive was idle and disconnected for a long time, the membrane inside could stick together. It is necessary to straighten it, assemble the device back and try again in work.

It is also possible that the membrane ruptures due to aging, or the body loses its tightness. In this case, the accumulator does not have an air cushion to facilitate smooth pressure build-up. Accordingly, the solution is either to replace the diaphragm with a gasket or to replace the battery completely. Although, if the reason is a small pinpoint corrosion of the tank, it is quite possible to fix the problem. To do this, a spool valve is cut into the rotten hole, and then the tank is pumped with a small amount of air..

How to minimize the likelihood of breakdowns

The rubber from which the HA pear is made is quite sensitive to the chemical composition of water and the presence of fine sedimentary particles. To avoid drying out, a mesh filter should be built into the supply line to retain particularly large particles.

Hydraulic accumulator connection method The presence of a coarse filter in front of the accumulator significantly extends the service life of the rubber membrane

It is not recommended to install cartridge filters before the pumping group because of the possibility of backflow. But if you use an expensive large-volume hydraulic accumulator, it will be advisable to carry the pumping group a little further from the battery and install a simple carbon filter in front of the collector unit, which will protect the drive and the rest of the system from the effects of chemically active substances.

Hydraulic accumulator for water supply systems: device, membrane replacement

Also keep in mind that low-cost manufacturers have much shorter case life due to thinner walls. Therefore, the presence of condensation on the equipment is a clear call to establish ventilation and stabilize the temperature regime at the installation site..

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