The main elements of an autonomous pumping station are a pump, a storage tank, a pressure switch for a hydraulic accumulator and a check valve. The pressure unit pumps the specified volume of water into the network. The accumulator accumulates and maintains a constant pressure to supply water to the consumer. The control unit provides a stable cycle of operation of the cold water supply system equipment. Let’s take a closer look at where it is applied and how to set up the accumulator and pressure switch.
Accumulator in the cold water system
Direct connection of a submersible or surface pump causes unstable water supply. The pressure unit is idling with minimal water consumption. The presence of a gravitational or pneumatic accumulator in the system does not require constant operation of the primary pressure pump. Reserve capacity maintains a constant flow of water for household and drinking needs. The supply of water reduces the dependence of individual water supply on external factors.
The gravitational design of the accumulator is an atmospheric capacitance with a float level sensor. An open tank is installed in the attic of the house, above the water points. The pressure in the system creates the weight of the liquid column. The operation of the pump is controlled by a float mechanism or level sensors.
Modern hydraulic accumulators for autonomous water supply work due to overpressure in the air chamber. The principle of operation of pneumatic batteries is based on the interaction of compressed air and water. The pump pumps water into a rubber bulb that is inside the case. The volume of the air chamber decreases, and the pressure increases. In the intervals between the inclusions of the unit, the air pushes a supply of water from the membrane into the network of the consumer.
Water does not come into contact with the inner walls of the sealed container. The air chamber separates the membrane from the metal housing. If the hydroaccumulator is used in the drinking water supply system, then the membrane material is chemically neutral rubber. When using a battery tank in a heating or hot water system, membranes with high resistance to high temperatures are used.
There are vertical and horizontal models of pneumatic accumulating tanks of various capacities. The connection of the hydroaccumulator determines the type of pump and the model of the drive. Horizontal tanks are used for remote surface units. The pressure blower is installed on the platform, in the upper part of the storage housing (i.e. the cylinder is below the self-priming pump).
Regulation of the water pressure switch for the pump. After reading the simple rules for adjusting the water pressure switch, as well as the subtleties of setting, you can carry out such work yourself.
Pumping stations with submersible units are completed with vertical drives. The accumulator is located above the depth pump installation level.
The volume of the hydropneumatic storage tank depends on the hourly water consumption, power and frequency of the pump on, the height of the piping system. The greater the water flow and the lower the pressure drop on the on / off of the pump, the greater the capacity of the accumulator.
Structural elements of the hydroaccumulator:
- sealed metal casing, designed to work under pressure (1.5? 6 atmospheres);
- elastic membrane – internal capacity for water supply;
- a flange with a valve for fixing the membrane to the body and filling it with water;
- nipple for air injection into the balloon air chamber;
- a valve to release air from the water chamber (for hydraulic accumulators whose volume exceeds 100 liters);
- bracket for mounting a small container on the wall or supporting legs, with mounting rubber gaskets for larger capacity models;
- The horizontal tank is supplied with a support bracket for joint installation of a surface pump with a hydraulic accumulator and a pressure switch.
Important! Primary filling of the accumulator hydraulic cylinder with water is performed gradually so as not to damage the integrity of the pear, since after storage, the walls of the rubber membrane are usually glued together.
The hydroaccumulator selection method is designed for individual houses that consume a large amount of water (sewage, bathroom, shower, several mixers, bidet, washing machine and dishwasher). By the number of points of water analysis determine the total coefficient of consumption and the maximum consumption of water for drinking needs. The volume of the accumulator is determined by the formula:
V is the volume of the accumulator, l;
Qmax – maximum water consumption for household and drinking needs, l / min;
a – the number of system starts per hour (the recommended value of 10 starts);
Pmin – pump start pressure, atm .;
Rmax – pressure off the pump, atm .;
Ro is the pressure of the air chamber of the hydroaccumulator, atm.
Standard installation of water supply for a small house with seasonal accommodation, as a rule, is equipped with a 24-liter hydroaccumulator. For a house with more than three paring points, choose a 50-liter drive. And in the technical passport of the equipment, the manufacturer indicates the total volume of the cylinder (the air chamber as well).
For domestic water supply of single-storey houses, the amount of pressure in one atmosphere is considered sufficient. However, it should be borne in mind that the air pressure of the air chamber must exceed the static pressure value of the highest water takeoff point.
The maximum value of the shut-off pressure depends on the pressure characteristics of the pump. The pressure that pumps the pump, divided by 10, corresponds to the value of the upper threshold for the automatic water supply system. The correction is made on the linear hydraulic resistance, the actual voltage of the electrical network, the technical condition of the equipment and the height of the water supply system at home.
The recommended difference between the on and off pressure of the pump for autonomous water supply is 1.0? 1.5 atmospheres. Increasing the factory setting (1.5 atmospheres) will reduce the reserve volume and increase the pressure in the system. High cold water supply pressure increases consumption, leads to wasteful use of energy resources.
The formula for calculating the magnitude of the required pressure in the accumulator:
Hmax – height in meters from the center line of the hydroaccumulator to the upper point of the water extraction (for a two-story private house 6? 7 meters).
The air pressure in the air chamber of the damper tank is checked and adjusted before installation, if the settings fail or when the water supply is broken. During the adjustment, the power of the pumping station is disconnected from the mains, the water from the accumulator is drained.
The pneumatic valve of the air chamber is located under the decorative cap on the tank body. Compliance or deviation of pressure from the specified operating parameters is determined using a pressure gauge connected to the spool. According to the measurement results, excess air is released, or the pressure of the air chamber is pumped up with a car pump.
If the adjustment of the operating parameters of the accumulator did not bring the desired result, then check the settings of the pressure switch.
A pressure switch controls the operation of the pump and regulates the filling of the pneumatic-hydraulic accumulator. The device integrates, controls and regulates the operation of the equipment of the cold water supply system.
The appearance of the pump control unit resembles a small plastic box. The device is mounted at the entrance to the storage tank. The pressure switch for the hydroaccumulator consists of a mechanical and an electrical part.
Elements of a standard pressure switch design:
- plastic case (cover with screws and base);
- metal membrane cover (with nut for connection to the pipeline);
- rubber membrane;
- brass piston;
- two threaded studs and nuts;
- large and small adjusting springs;
- base metal plate;
- hinged platform;
- electrical contact assembly with a flat spring;
- cable clamps;
- terminal block.
The spring adjustment mechanism and the connection box are protected by a plastic cover. A metal base plate at the bottom is supported by a plastic case. The base separates the working body (the membrane with a piston) from the actuator (a hinged platform, two adjusting springs on the studs and an electrical contact assembly).
The electrical part of the water pressure switch is a two-contact switching relay of electrical circuits. The legs of the electrical contact assembly are clamped between the metal base plate and the plastic case. Two couplings for clamping the cable (from the mains and the power supply line of the pump) and the relay connection to the hydraulic accumulator are located on the base of the plastic housing.
Standard inlet diameter? in. On the instrument side, the internal cross section of the attachment nut to the adapter is limited by a rubber membrane. The reciprocating movement of the elastic membrane is communicated to the brass piston, which transmits the force to a hinged metal platform.
From above, on the moving edge of the platform, a large and small spring is pressed against the force of the piston. The degree of compression of the large spring regulates the moment of switching on the pump. The range of deformation of the small spring provides off the pressure unit.
There are schemes for connecting the pressure switch to the hydroaccumulator for water and electricity.
How to connect the water pressure switch?
The connecting pipe of the connection node of the pressure accumulator of the accumulator to the pipeline is rigidly fixed. The device is assembled. Before assembly, sufficient space must be provided to allow the housing to rotate when mounting the pressure switch.
The device is screwed onto a separate thread embedded in the pipeline or mounted directly on the outlet of the accumulator through a special fitting. A five outlet fitting allows you to install a test pressure gauge next to the pump operation control device.
How to connect the pressure switch to the hydroaccumulator on the electrical part?
Direct activation of the pressure switch is produced from the mains 220V, provided that the operating current of the pump does not exceed 10 Amps.
Before connecting the cable, remove the protective plastic cover from the device. The electrical cable of the power line or pump is driven into the appropriate coupling. Outside, the wire is fixed with a nut with a plastic crimp ring. The designation of contact groups is indicated on the housing. The end of the cable is divided into conductors. The phase, neutral, and grounding are stripped of the insulating braid and connected to the terminals of the contact group.
Important! Electrical installation and adjustment work is carried out with the equipment disconnected from the network. The electrical connection is performed in compliance with the regulations of technical operation and safety in electrical installations.
The relay controls the minimum and maximum pressure in the storage tank, maintains the pressure difference when the pump is turned on / off. The limit of permissible adjustment values of the relay depends on the hourly flow rate and pump power.
Characteristics of the factory settings are specified in the product data sheet. The standard value of the pressure switch setting for water supply systems is 1.0 ± 5.0 atmospheres. Starting pressure – 1.5 atmospheres. The range of operation of the pump motor is 2.5 atmospheres. The maximum shutdown pressure of the unit is 5.0 atmospheres.
If the factory settings are not relevant or the unit has malfunctioned, the adjustment and adjustment of the water pressure switch is carried out independently using a pressure gauge. The control device is installed on the reservoir collector. Correction produced by the readings of the pressure gauge, after the pump is turned off. The pressure drop is created by opening the valve at the point of water extraction closest to the accumulator.
Adjustment of the pressure switch of the hydroaccumulator is carried out under pressure, without disconnecting the pump station from the power supply. The pump must fill the cumulative capacity and increase the pressure in the network. When the relay operates and turns off the engine of the unit, it is necessary to remove the plastic housing cover and completely loosen the degree of tension of the small spring mechanism.
How to adjust the water pressure switch to the minimum pump on pressure?
Setting a large adjusting spring:
- the clamping nut is rotated clockwise to increase the starting pressure;
- weakening the tension – reduces the pressure of the relay and the inclusion of the engine;
- to check the result of the adjustment, open the tap and drain the water until the pump is turned on.
How to adjust the pressure switch of the accumulator on the pressure off the pump?
Setting the small adjustment spring:
- the nut on the stud of the small spring is tightened to increase the pressure difference;
- loosening the tension allows the engine to shut off pressure;
- The result of the correction is checked by test switching on the pump.
If the reading of the gauge coincides with the required value when switching on / off the engine, the adjustment is complete. If it is impossible to adjust the existing device on their own, use the services of qualified specialists or buy a new device. If it is decided to buy a pressure switch for the accumulator, then pay attention to the compatibility of work with pumping equipment and the method of connecting the device to the power supply.
Important! Increasing the starting value of the factory setting of the pressure accumulator of the accumulator (above 1.5 atmospheres) creates a critical load on the diaphragm of the accumulator. The operating range of the pump is changed taking into account the maximum allowable pressure for water fittings. The limiting pressure for which the sealing rings of mixers and taps are designed is 6 atmospheres.
The air pressure of the air chamber of the hydroaccumulator does not affect the operation of the pressure relay and the pumping station as a whole. The absence or lack of air leads to excessive stretching of the diaphragm and the pump is triggered with each water withdrawal from the system. Increased overpressure of the air chamber reduces the amount of water in the membrane and the response interval of the pressure installation. Frequent on-off pump reduces the service life of the unit.
Normal operation of the pumping station is possible under the condition that the pressure of the air chamber of the accumulator is 10% lower than the pump activation pressure. Competent adjustment and adjustment of the pressure switch and accumulator will ensure the pump operation without overloads, optimal filling of the storage tank with water. An integrated approach to setting up and adjusting equipment will extend the service life of the membrane and increase the reliability of the autonomous water supply system.