Orifice Steam Trap - Disadvantages of Design
- Will fail closed
- No Strainer or Check Valve
- Superheat
- Waste steam or back up water based on variable conditions
(Listed below is a report by the Veteran’s Administration as to the
use of the orifice steam trap, December 4, 2001.)
ISSUE:
These have been proposed to VA for use on energy-saving projects. They
have been installed on all the steam distribution systems at one (or more)
VA Medical Centers as part of an Energy Saving Performance Contract. It
is recommended that this type of steam trap not be used.
DISCUSSION
This type of steam trap has no mechanisms to modulate and control the capacity
of the trap. The trap has only a small fixed orifice which is sized
by the manufacturer, or his representative, for a “normal” constant
volume of condensate. The lack of any mechanisms is a selling point
for the trap design since, theoretically, maintenance will be less than with
other types of traps.
One problem is that there are almost no applications where there is a constant
volume of condensate. Even on a steam distribution system, the quantity
will vary when the system is warmed-up. In a warm-up situation, the amount
of condensate will be much greater than the amount of condensate from the normal
radiation loss when the line is in continuous service. Failure to promptly remove
the condensate from the steam line can result in dangerous water hammers.
A major problem with orifice traps is the potential plugging of the small
orifice (or the fine mesh strainer which precedes it) due to contaminants
in the steam system. This problem has been reported at a VAMC.