5. LOCATING FAULTY STEAM TRAPS
An ultrasonic test of steam traps is a positive test. The main advantage to ultrasonic testing is that it isolates the
area being tested by eliminating confusing background noises. A user can quickly adjust to recognizing differences
among various steam traps, of which there are three basic types: mechanical, thermostatic and thermodynamic.
When testing steam traps ultrasonically:
1. Determine what type of trap is on the line. Be familiar with the operation of the trap. Is it intermittent or
continous drain?
2. Try to check whether the trap is in operation (is it hot or cold? Put your hand near, but do
not
touch the trap,
or, better yet, use a non-contact infrared thermometer).
3. Use the contact (stethoscope) module.
4. Try to touch the contact probe towards the discharge side of the trap. Press the trigger and listen.
5. Listen for the intermittent or continuous flow operation of the trap. Intermittent traps are usually the inverted
bucket, thermodynamic (disc) and thermostatic (under light loads). Continuous flow: include the float, float
and thermostatic and (usually) thermostatic traps. While testing intermittent traps, listen long enough to gauge
the true cycle. In some cases, this may be longer than 30 seconds. Bear in mind that the greater the load that
comes to it, the longer period of time it will stay open.
In checking a trap ultrasonically, a continuous rushing sound will often be the key indicator of live steam passing
through. There are subtleties for each type of trap that can be noted.
Use the sensitivity levels of the Sensitivity Selection Dial to assist your test. If a low pressure system is to be
checked, adjust the sensitivity UP toward 8; if a high pressure system (above 100 psi) is to be checked, reduce the
sensitivity level. (Some experimentation may be necessary to arrive at the most desirable level to be tested.) Check
upstream and reduce the sensitivity so that the meter reads about 50% or lower, then touch the trap body down-
stream and compare readings.
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 (about 50%).
2. move 6 - 12 inches (15.2-30.5 cm)
downstream
and listen. Flashing steam will show a large drop
off in intensity while leaking steam will show little drop off in intensity.
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trap shot
