Steam trap what is

At startup, the trap is wide open, discharging condensate and noncondensables. As the temperature approaches that of the steam, vaporization of the volatile liquid creates a pressure differential, causing the bellows to expand and close the valve against its seat.

As the condensate cools, the volatile liquid condenses and lowers the internal pressure on the bellows, causing it to retract and open the valve, permitting the condensate discharge cycle to continue. Bimetallic trap operation is based on the characteristic that two dissimilar metals have different expansion rates. When the bimetallic element is heated, the different expansion rates of the metals causes it to deflect or bend, which provides movement to close a valve. Thermodynamic traps use the difference in velocity between steam and condensate to operate.

Condensate entering the steam trap body moves relatively slowly compared with steam and is freely discharged through a valve a free floating disk. When steam reaches the underside of the disc, its velocity is much higher than that of condensate, creating a pressure drop that closes the valve head.

The valve stays shut until the steam pressure above the disc drops, allowing the valve to open and the discharge cycle to repeat. Premium content requires special account permissions. We need a little more information from you before we can grant you access. Contact Us. Publication Date. Various types of steam trap mechanisms operation principles have been developed to automatically discharge condensate and non-condensable gases. The most widely used mechanisms are those that rely on differences in temperature, specific gravities, and pressure.

Each of these types of steam traps has its own advantages and applications. Visit the article The History of Steam Traps for further information on the specific types of steam traps. Products Browse Products by Category.

Find a Specific Model. Technical Documents. Product Solutions. CAD 3D. Archived Documents. Webinar Recordings. Steam Theory. We aimed to explain our audit experiences and technical knowledge to partners and introduce different type of steam traps and all related products in detail in this book.

The aim of a steam trap is discharging the condensate from the steam pipe line while trapping the steam. Steam use its potential heat during the applications and by the radiation heat loses on pipelines, steam turns to condensate. In case this condensate not discharged from the pipeline, it causes cavitation and water hammer beside reducing the quality of the steam. An ideal steam trap should have the ability of air venting together with discharging the condensate.

Float traps come with an optional air vent which quickly removes air and other gases during start ups. Float traps or ball float traps are ideal for process heating applications.

Float traps are designed in such a way that the valve seat is always submerged under water preventing any steam loss. The discharge is continuous and modulates with the condensing rate. It is unaffected by changes in inlet pressure. A separate thermostatic air vent independently purges air giving a fast start-up. As condensate enters the trap body, the ball float being hollow, floats over the condensate.

As condensate level increases, condensate causes the ball float to rise and place the modulating discharge valve in a position that will pass the condensate continuously as it enters the trap. The condensate level in the trap body is maintained above the discharge valve to provide seal against the loss of steam.

As the name explains, inverted bucket traps have an inverted bucket inside them. These are mechanical type of steam traps working on the principle of buoyancy. Initially, the bucket is resting at the bottom of the steam trap and the valve seat is wide open. At star-up, air will enter the steam trap and will be discharged out through the bleed hole.

As condensate enters the trap, it forms a water seal inside the body. The weight of the bucket keeps the valve off its seat and so condensate can flow around the bottom of the bucket and out of the trap. When steam enters the underside of the bucket, the bucket becomes buoyant and rises.