large hydraulic resistance, the possibility of jamming the bolt in the guide of the cap when using the valve systems with contamination of the environment. Safety valves safety valves – are kind of valves designed for automatic protection of technological systems and pipelines from the unacceptable increase in pressure of the working environment through its partial relief from the protected system. Most distributed spring check valves, in which the working fluid pressure counteracts the force of compressed spring. Direction of the working environment – under the spool. By way of issue of the working environment safety Valves are classified as: valves open, operating without backpressure and discharging working environment directly into the atmosphere; valves closed, discharging the working environment in line (suction line pumping devices, 'flare' line, etc.). In this case the valve is backpressure. Height lift valve, which determines the capacity of valves, they are divided into: nizkopodemnye (Malopodemnye), whose height is approximately 0.05 valve seat diameter. Such valves are used, usually in systems with a liquid working medium, which does not require more bandwidth, full-lift, y whose height more than 0,25 spool seat diameter.
Such valves are used in systems with gaseous media. Valve opening occurs immediately at full speed spool. Safety valves are available in two versions – with a device for manually opening (manual override) or without such a device. Advantages of spring safety valve: the relatively small size with large flow areas; the ability to install both the vertical and horizontal positions, the ability to obtain high throughput.