The purpose of a steam trap is not as the name may indicate to trap steam, but rather to trap condensate in a steam line. The trap is mounted on or adjacent to a steam line.
The trap should open and capture condensate when there is condensate in the steam line. The trap should be closed when steam is present in the line. It is usually important that the traps perform closing and opening quickly to reduce steam and condensate losses. Condensate trapped in the steam trap may be purged into a condensate return system or may be purged to the atmosphere depending on system design.
There are three types of steam traps, they are:
- Ball float & bucket traps are mechanical steam traps. They operate be response to the difference density between and steam and condensate.
- Thermostatic steam traps operate by noticing the temperature difference between condensate and steam.
- Thermodynamic traps operate by the difference in thermodynamic energy between steam and condensate.
For more information on Thermostatic and thermodynamic steam traps see CMS volume 2.