Safety valves: application and types

It is difficult to overestimate the role of safety valves in the heating system, because of their proper operation, tuning and quality depends on the availability and reliability of engineering systems. Safety valves, as it becomes clear from their name, protect the system from increasing the pressure beyond the permissible value.

The heat carrier in the closed circle from heating increases in volume, and the volume increase should appear in the expansion tank, while the pressure in the heating circuit also increases. In the normal operation of the system, the safety valves must be in the closed position, only in the case of improper adjustment or improper selection of the expansion tank, when the excess volume of the coolant does not enter it and the pressure rises above the maximum permissible level, the valve should operate.

Safety valves are installed in systems with closed circuits in which the heat carrier is heated: these are systems with a solar collector and heat pumps; Closed systems with hot water supply, which are connected to heat networks; And also connected through heat exchangers or autonomous boilers.

When selecting a valve, it is necessary to study the characteristics of each element of the heating system. It is selected in such a way that the pressure for its operation is not greater than the maximum operating pressure of the less stable heating element. In addition, the pressure for triggering must be in the middle of all adjustable values. Safety valves have an outlet, most often one or two sizes larger than the inlet one.

In systems with expensive equipment or with an increased risk of pressure increase, it is recommended to install two valves located side by side. In addition to systems with closed loop hydraulic circuits, the valves can be used in any device in which the pressure can exceed the maximum allowable value. These can be systems that are connected to the heat network by a dependent scheme, in the hydraulic operation of which the possibility of emergency situations with a pressure increase above the maximum values is not excluded.

In this case, safety valves are installed in the return pipeline and are selected so that the flow of the discharged heat carrier is greater than the flow rate that enters the heating system in emergency mode.

By design, the valves are divided into membrane and spring.

The internal surface of the membrane valve, as well as the sealing surface of the connecting flange, are covered with protective materials resistant to the influence of various aggressive chemicals. Thanks to it, the working parts are isolated from the external environment. The guides ensure the correct movement of the spool, which compresses the membrane.

The spring safety valve can be used for various settings of the triggering pressure due to the configuration with different springs. Also, many valves are produced with a special mechanism (fungus, lever) for control purging.