In industrial-scale water systems, devices such as control valves, typical pressure regulators, and other throttle valves are often used as pressure control devices. Regulators are different, some control the pressure after themselves, others - before themselves. The water pressure reducing valve is considered a direct acting regulator. It controls the pressure after itself, but on the condition that this pressure is less than half of the input values.
Characteristics of the movement
The pressure reducing valve is controlled by the liquid medium that flows through the working pipeline by moving the control device by the force resulting from the dynamic change of the controlled indicator.
Structurally, the pressure reducing valve consists of three main elements: a regulating body, i.e. plates, the setting element, or spring, and the comparison element, which is the membrane.
The principle of operation of the valve is to throttle the liquid medium. Water flows from a high-pressure cavity to a low-pressure cavity, which communicate through a gap betweenseat and valve disc. The sensing element is usually soft rubber diaphragms with two fabric gaskets, but in some models it can be a piston with sealing cups or rings made of rubber-based material. As a locking mechanism, plates made of vulcanized rubber and metal alloy are used.
Valve selection
Each pressure reducing valve for water is selected based on the Kvs value (capacity of the pipeline fittings). Among other technical characteristics of all pressure reducing valves, the maximum Kvs value for all sizes must be indicated.
The pressure reducing valve is chosen so that the required value of throughput is in the interval between its minimum and maximum values. To select the optimal size of the product, they are compared with the tables of known indicators of the valve throughput. However, for certain types of valves, the capacity cannot depend on the nominal diameter (as is the case with sizes DM505, DM510 - 518). It is strongly not recommended to use fittings with a nominal diameter two standard sizes smaller than the working diameter of the pipeline.
Reducing valve settings
The most accurate designation of the outlet pressure setting range can be achieved by bringing the desired pressure setting level as close as possible to the upper threshold of the range. If the desired outlet pressure is, for example, 2.3 bar, then select the rangeshould be in the range from 0.8 to 2.5 bar, and not as much as 2-5 bar. If it is necessary to use a wider range, special fittings can be used.
Valve protection
It is known that the speed of water flow in the valve seat is much higher than the speed of its movement in the pipeline. And it is likely that solid particles present in the water can damage not only the seat itself, but also the plunger (cylindrical rod). To protect the pressure reducing valve, as a rule, a coarse filter is installed in front of it.
Valve types
The following valve types are widely used: DM505, DM506, PRW25, KAT40, DM652, DM664, KAT30, RP45, DM604, DM613, DM810, DM814, DM815. They differ in terms of throughput, operating temperature, pressure settings, material used for manufacturing. Each consumer will be able to choose the option that suits the cost and characteristics.
