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General Steam/Condensate/Flash Steam Confirmation
In instances where it may be difficult to determine the sound of steam, flash steam or condensate,
1. touch at the immediate downstream side of the trap and reduce the sensitivity to get a mid-line reading on the
meter ("50").
2. move 15-30 cm (6 - 12 inches) downstream and listen. Flashing steam will show a large drop off in intensity
while leaking steam will show little drop off in intensity.
Inverted Bucket Traps
Inverted Bucket Traps normally fail in the open
position because the trap loses its prime. This condition means a
complete blow-through, not a partial loss. The trap will no longer operate intermittently. Aside from a continuous rushing
sound, another clue for steam blow-through is the sound of the bucket clanging against the side of the trap.
A Float and Thermostatic
A Float and Thermostatic trap normally fails in the
"closed" position. A pinhole leak produced in the ball float will cause
the float to be weighted down or water hammer will collapse the ball float. Since the trap is totally closed - no sound will
be heard. In addition, check the thermostatic element in the float and thermostatic trap. If the trap is operating correctly,
this element is usually quiet; if a rushing sound is heard, this will indicate either steam or gas is blowing through the air
vent. This indicates that the vent has failed in the open position and is wasting energy.
Thermodynamic (Disc)
Thermodynamic
traps work on the difference
in dynamic response to velocity change in the flow
of compressible and incompressible fluids. As steam enters, static pressure above the disc forces the disc against the
valve seat. The static pressure over a large area overcomes the high inlet pressure of the steam. As the steam starts to
condense, the pressure against the disc lessens and the trap cycles. A good disc trap should cycle (hold-discharge-
hold) 4-10 times per minute. When it fails, it usually fails in the open position, allowing continuous blow through of
steam.
Thermostatic Traps
(bellows & bimetallic) operate
on a difference in temperature between condensate and
steam. They build up
condensate so that the temperature of condensate drops down to a certain level below saturation temperature in
order for the trap to
open. By backing up condensate, the trap will tend to modulate open or closed depending on
load.
In a bellows trap, should the bellows become compressed by water hammer, it will not function properly. The
occurrence of a leak will prevent the balanced pressure action of these traps. When either condition occurs, the trap
will fail in its natural position either opened or closed. If the trap fails closed,
condensate will back up and no sound
will be heard. If the trap fails open, a continuous rushing of live steam will be heard. With bimetallic traps, as the
bimetallic plates set due to the heat they sense and the cooling effect on the plates, they may not set properly which
will prevent the plates from closing completely and allow steam to piss through. This will be heard as a constant
rushing sound.
