Bimetallic Steam Traps

February 15, 2013

The use of steam traps is standard practice when engineering systems that require the quick removal of condensate. Condensate, if allowed to collect, will inhabit space designed for steam, keeping it away from heat exchange surfaces. Eliminating this condition is not only critical to proper system operation, but is essential to effective utilization of steam and sensible heat. There are a number of types of steam traps available; of thermostatic traps, there are bellows, capsule, liquid expansion, and bimetallic, just to name a few. Each has advantages, and is designed for specific operating conditions.

Spirax-Sarco actually offers a number of great resources on the distinguishing features of various types of traps.  One that recently caught our eye on Twitter was a thorough video explanation of their bimetallic steam traps. These are ideal for applications that see superheated steam and pressure. Because of this design criterion, bimetallic steam traps are manufactured from robust materials, and constructed to withstand high pressure and water hammer.  This design relies on thermal expansion, which is inherently energy-efficient, and includes features such as self-draining, fail open, and because of all-metal construction; they are also resistant to freezing.

As the video demonstrates, bimetallic steam trap operation relies on the thermal expansion of metal plates making their operation simple and reliable. During normal operating temperatures, steam and condensate enter the steam trap body, this causes the bimetallic plates to expand, which closes the condensate discharge valve. In the closed position, the condensate valve will allow the buildup of condensate in the steam trap; this causes the temperature within the trap to decrease. Once the temperature drops to a predefined range, typically 50°F to 100°F below normal operating temperatures (range is adjustable), the bimetallic plates contract, opening the valve and draining the built up condensate. Have additional questions? Feel free to contact us today.