It is difficult to overestimate the role of safety valves in the heating system, because the operability and reliability of engineering systems depend on their proper operation, tuning and quality. Safety valves, as their name implies, prevent the system from increasing pressure beyond the permissible value.
The heat carrier in a vicious circle from heating increases in volume, and the increase in volume should be in the expansion tank, while the pressure in the heating circuit also increases. During normal operation of the system, the safety valves should be in the closed position, only in case of incorrect adjustment or incorrect selection of the expansion tank, when it does not include excess coolant volume and the pressure rises above the maximum allowable level - the valve should work.
Safety valves are installed in closed-loop systems in which the coolant is heated: these are systems with a solar collector and heat pumps; closed systems with hot water supply, which are connected to heating networks; as well as 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 more than the maximum working pressure of a less durable heating element. In addition, the response pressure must be in the middle of all set values. Safety valves have an exhaust pipe, most often one or two sizes larger than the inlet.
In systems with expensive equipment or with an increased risk of pressure buildup, it is recommended that two valves be installed side by side. In addition to systems with hydraulic closed circuits, valves can be used in any device in which the pressure is able to exceed the maximum allowable value. These can be systems that are connected to the heating network in a dependent manner, in the hydraulic operation of which the possibility of emergency situations with increasing pressure above maximum values is not excluded.
In this case, safety valves are installed in the return pipe and are selected so that the flow rate of the discharged coolant is greater than the flow rate that enters the heating system in emergency mode.
By design, the valves are divided into diaphragm and spring.
The inner surface of the diaphragm valve, as well as the sealing surface of the connecting flange, are coated with protective materials that are resistant to various aggressive chemicals. Thanks to him, working parts are isolated from the external environment. Guides ensure the correct movement of the spool, which compresses the membrane.
The safety spring valve can be used for various limits of setting the triggered pressure due to the configuration of various springs. Also, many valves are available with a special mechanism (fungus, lever) for control purging.