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 a closed condensate return system. Experience is required, but much can be
derived from the sounds made, or not made, by traps while operating. The
following descriptions apply to sound detection.
(a) By listening carefully to steam traps as they cycle, a judgment can
be made whether they are operating properly or not. An inspector can hear the
mechanisms working in disk, inverted bucket and piston traps. Modulating
traps give only flow sounds which are hard to detect if the condensate load is
low. However, the performance of a suspected trap should be cross-checked
visually or by temperature measurements since a trap that does not cycle may
be either failed open or under a heavy condensate load.
(b) Simple equipment can be effective, such as industrial stethoscopes
o r a 2-foot length of 3/16-inch steel rod in a file handle. They are used
simply by placing the probe end on the trap bonnet and your ear against the
other end.
( c ) If there are a large number of traps or situations where traps are
congested or close to other equipment generating noise, ultrasonic listening
equipment is warranted. These instruments have earphones, are equipped with
probes, and allow selection of sound frequency bands. High frequencies are
sensitive to flow noise, and low frequencies are sensitive to mechanical
sounds.
2.3.3 Temperature Measurements. Diagnosing trap condition from temperature
differences between upstream and downstream pipes is the least reliable
inspection method. It can be useful in combination with visual or sound
inspection as long as the potential ambiguities are recognized. Equipment
types range from sophisticated infrared meters, to simple thermometers and
heat sensitive markers. A contact thermocouple thermometer is recommended.
2.3.4 Measurements Technique. F i l e contact points on the pipe clean. Take
temperature measurements immediately adjacent, no more than 2 feet, on either
s i d e of the trap. The readings should be in the ranges shown in table 3-1 for
t h e pressures in the supply and discharge/return lines. Interpretation of the
temperature readings requires knowledge of the line pressures. For example, a
supply line at 150 psig with temperature of 340F, and a return line at
15-psig with temperature of 230F, indicate a properly operating trap.
2 . 4 Inspection Procedures.
2 . 4 . 1 Data Preparation. B e f o r e beginning routine periodic inspections, the
trap inventory should be current, steam trap maps of buildings and exterior
areas should be prepared, and traps tagged with stainless steel tags for
p e r m a n e n t identification. Inspectors should be provided with effective and
convenient equipment. The use of two different colored tags is one method for
i d e n t i f y i n g cold traps for investigation: a n d failed or faulty traps for
maintenance and repair. A suggested equipment list follows and is illustrated
i n figure 3-8:
Carrying pouch and belt
Clipboard with trap lists and trap maps
3-31
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