Page 288 - Boiler plant and distribution system optimization manual
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Steam Traps 273
Inspection schedules but none of the methods provide a cure-all for
The ideal is all traps functioning properly. trap troubleshooting.
This must be balanced against cost effective use Table 14.10 is a steam trap troubleshooting
of time and materials. Each location offers differ- guide, useful for trap inspections.
ent challenges. Dirty systems, above normal acid
accumulations and problems with the trapping visual Observation
stations all point to judgment playing a major role Observing the discharge from a trap is the
in trap maintenance. Table 14.8 and 14.9 are com- only positive way of checking its operation.
monly used trap inspection schedules. No special equipment is required but train-
ing and experience are necessary, particularly for
recognizing the difference between flash steam
and live steam.
• Flash steam is the lazy vapor formed when
the hot condensate gives up 1 energy when
reducing pressure through the trap.
• Live steam is a higher temperature, higher
velocity discharge, and usually leaves the
discharge pipe with a short clear, almost in-
Table 14.8—Trap inspection schedule. visible, section of flow before condensation
begins and a visible steam cloud develops.
Sound Detection
Some traps can be heard cycling on and off
as they discharge condensate. The disk, inverted
bucket and piston type of traps have this charac-
teristic.
Some traps continually modulate like the
float traps or expansive element and some ther-
mostatic traps; they only give off flow sounds.
However if they aren’t working, they don’t give
off any sound.
An automotive stethoscope or other simple
sound transmission device may be adequate. If
Table 14.9—One manufacturer recommends inspec- there is a Jot of noise around or a lot of traps giv-
tion frequencies based on system pressure. ing off noise, then an ultrasonic listening device
may be warranted. They can sense high frequen-
Traps serving critical process equipment cy (an indication of flow) and low frequency me-
may need special inspections during very cold chanical noises (indicates operation).
weather to guard against freezing damage.
The basic methods of inspecting traps are: Temperature Measurements
A. Visual observation Diagnosing trap condition from temperature
B. Sound detection differences between upstream and downstream
C. Temperature measurements. pipes is the least reliable inspection method. It
can be useful in combination with visual or sound
Visual observation is the best and least cost- inspection as long as the potential ambiguities are
ly method of checking trap operating conditions, recognized.
