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In gearboxes, before missing gear teeth may be detected as an abnormal click, the normal sounds of gears
must be understood. In pumps, certain pumps will have surges which may confuse inexperienced operators
by the constant shifting of the meter readings. The surge pattern must be observed before a lower,
consistent meter reading can be recognized as the true meter reading.
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 continuous 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 10; 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 then touch the trap body downstream
and compare readings.
Frequency Selection (UP2000 only)
Occasionally it may be necessary to "tune in" to a steam trap. In some systems, specifically float type traps under
low or moderate pressure load, a wide orifice will not produce too much ultrasound. If this is the case touch the trap
on the downstream side, reduce the frequency, start at 20 kHz and listen for a lower frequency trickling sound of
water. For other
subtle trap sounds, such as determining the difference of condensate vs. steam sounds, try to
listen at FIXED BAND. If this proves difficult, gradually rotate the Frequency Selection Dial down
(counterclockwise) until the specific sounds are heard. Steam will have a light, gaseous sound, condensate will
have additional overtones to its rushing sound.
