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Posted by Joe Lambert on March 29, 2002 at 07:23:01:
In Reply to: Orifice Steam Traps posted by John Gilliland on March 25, 2002 at 07:56:57:
An orifice steam trap is indeed a hole in a piece of metal. There are problems with these devices. The hole needs to be sized for the exact condensate load of the system. If the hole is too big you will waste steam, if it is too small you will back up condensate.
The problem is that a steam system never runs under constant conditions. Temperatures, flowrates, etc. are constantly changing, so there is a good possibity that these devices will both back up condensate and blow live steam sometime in the system.
Another problem is that for some application the actual condensate load is very small (drips and tracers). Most manufacturers of traps have limited the orfice size in the smallest capacity traps to about 3mm. There is then some type of actuator that opens and closes the trap according to actual condensate load, because even this 3mm is too large for the small flow rates associated with the drip and tracer applications. They do not make it smaller because of the dirt problem. A smaller orifice would get clogged with dirt unless you have a very fine mesh strainer before the trap, which would cause other problems in the system.
So, as you can probalby tell, I am not a fan of orifice traps. I do not believe they can work in 99.9% of applications in a facility. There are more reasons not to use them than are listed above.