Steam Pressure reducing ValveSpirax Sarco

In the installation of pressure reducing valves in a steam system, it is necessary to consider sufficiently about the various valves and piping around the pressure reducing valve. It becomes an important point in quality, productivity, and energy saving.

Pressure Reducing Valve

A dual check backflow preventer is similar to a double check valve in operation. It has two independent spring-loaded check valves. However, dual check valves usually do not include shutoff valves, may or may not be equipped with test cocks or ports, and is generally less reliable than a double check valve.[4]

It consists of two check valves assembled in series.[2] This employs two operating principles: firstly one check valve will still act, even if the other is jammed wide open. Secondly the closure of one valve reduces the pressure differential across the other, allowing a more reliable seal and avoiding even minor leakage.

The most typical pressure reducing valve for steam is GP-1000 series. Since it is the internal detection type which has the outlet side pressure sensing hole inside of the main body, piping work is easy. Moreover, by adoption of the piston which holds the stable operation realized by two-points guide structure for a long period of time, flexibility is high, and it can be used for almost all uses as a pressure reducing valve for steam of 1.0 MPa or less.

Steam pressure reducing valveworking principle

A double check valve or double check assembly (DCA) is a backflow prevention device designed to protect water supplies from contamination.[1] It is different from the two-way check valves (sometimes erroneously referred to as double check valves) used in air brake systems on heavy trucks which select from the highest pressure source.

Small valves may be so compact as to be barely noticeable particularly when they are integrated into the bodies of existing taps (faucets). Larger check valves may be installed with ball valves at the ends, for isolation and testing. Often, test cocks (very small ball valves) are in place to attach test equipment for evaluating whether the double check assembly is still functional.

steam pressure reducingvalve: adjustment

With taking advantage of the use and effect of pressure reduction, it is necessary to perform installation with higher reliability and higher controllability.

The double check valve assembly is suitable for prevention of back pressure and back siphonage, but is not suitable for high hazard applications. It is commonly used on lawn irrigation, fire sprinkler[2] and combi-boiler systems.[3] If the hazard is higher, even a relatively low hazard such as using antifreeze in the fire sprinkler system, then a more reliable check valve such as a reduced pressure zone device may be mandated.

Due to high Cv value and outstanding controllability, this type is the most appropriate when more precise pressure reduction is necessary.Moreover, with the original diaphragm case structure, great durability is realized by distributing equally the stress added to the diaphragm.

By adopting a diaphragm with a large taking pressure area as a main valve controlling part instead of a piston, it can react to a slight change of outlet side pressure sensitively. Moreover, with the external detection system, highly precise pressure reducing is possible by exact perception of the outlet side pressure without influence of steam turbulence.