Maximum temperature tolerance and durability
Danfoss has continually been at the forefront of significant developments in solenoid valves for steam systems. Over the years, customers have identified a variety of problems with their steam systems, including high temperature intolerance, impurities in the steam and aggressive corrosion. And Danfoss has always improved the materials used in its valves, solving the problems through increased temperature tolerance and durability.
To increase temperature intolerance, Danfoss replaced the rubber diaphragms commonly used in servo-operated solenoid valves. A piston-cylinder servomechanism consisting of a brass piston with a PFTE (Teflon) ring helped valves withstand temperatures up to 185º Celsius and 10 bar gauge pressure.
Another issue facing customers was dirt, rust and impurities in the system which led to valve failures. Danfoss designers used their experience from the cooling industry to develop a new servo concept to overcome this problem. The EV225B valves feature a PTFE diaphragm type that does not jam. This is ideal for situations with contaminated steam and is also suitable for temperatures up to 185º Celsius.
Using technical water in steam systems requires a valve that can withstand technical water’s corrosive nature. Brass is particularly vulnerable to corrosion from technical water, making the area between the cone and seat vulnerable to particles and impurities. These problems were overcome by using dezincification resistant brass and acid proof stainless steel for the seat.
Danfoss designers also identified a need for seals and rings made from a temperature stable material that is not prone to leakages. A new O-ring material based on space shuttle technology was developed. This is easy to mount and temperature stable – solving yet another valve performance issue.
Continual research and development to meet customer needs has ensured that Danfoss remains the world’s number one manufacturer of solenoid valves for steam.
By Karsten Holtebo, Application Manager, Marine