| TESTING TIPS FOR COMMON PROBLEM
AREAS |
| Most Exchangers, Boiler Casings or Shutoff Valves |
| It is essential to know how
each steam trap or valve works under specific conditions in order to be
able to diagnose a problem correctly. To determine leakage or blockage,
touch the ultrasonic instrument upstream of the valve or trap and reduce
the sensitivity of the, detector until the meter reads about 50. |
| If you need to hear the specific
sound quality of the fluid, simply tune the frequency until the sound you
would expect to hear becomes clear, Next touch downstream of the valve
or trap and compare intensity levels and, for traps, sound pattern levels.
If the, sound level is louder downstream, then fluid is passing through.
If the sound level is low, then the valve or trap is closed. |
| Check Valves |
| When check valves are placed
closer than three feet downstream of blast action traps (such as Inverted
bucket or thermodynamic types) flappers may loosen or even break free.
Damaged check valves will usually become noisy. |
| When control valves are grossly
oversized they are forced to work close to their seats. High velocity wet
steam acts almost as sandpaper, cutting the seat when a mixture of steam
and water is forced through the tiny crevice. |
| With an ultrasonic instrument
you can distinguish between normal machine noises and sounds that spell
trouble. To verify data, use the instrument to test nearby units and compare. |
| Control Valves/Pressure-Reducing Valves |
| Air operated control valves
may be leaking at or around their diaphragms. Scan the exterior sections
listening for the turbulent sounds created by a leak. Test ultrasonically
for internal leakage as you would for any other valve. It will be necessary
to momentarily close the valve to perform definitive testing. |
| For those valves with diaphragms,
listen for leakage at the small bleed hole. This is a dead giveaway that
a rupture has taken place. |
| Solenoids |
| Listen for leakage through solenoids
that are in a closed position. You will be able to detect which valve is
leaking even when it is part of a large bank of valves. If you are in doubt
about a judgment call, compare with similar valves. |
| Relief Valve |
| In a steam system, relief valves
that have opened by excess pressure may not reseat properly. Some with
softer seats may be chattering or may suffer microscopic steam and water
cuffing. Ultrasonic testing will detect the turbulent passage of steam
or vapor as it moves through the leak site. Touch the instrument's stethoscope
at the point on the valve closest to the orifice and then touch the downstream
piping. Leaking and blowing valves are easily identified. Augment your
test with a hand-held infrared thermometer for temperature differentials. |
| Condensate Return Pumps |
| Listen for the static noise
indicating a vaporization bubble collapsing around the impeller. If in
doubt, test similar pumps and compare. Remember to test volute pump casing
temperatures with an infrared thermometer. |
| Pressure Powered Pump Needle Valves |
| The needle valves on steam or
air powered condensate movers, like any other mechanism, will deteriorate
over time. Listen for seepage of steam through worn valves, usually indicated
by a high pitched whistling sound. When more then one pump exists, comparisons
can be useful. |
| Valve, Piping and Gland Leakage |
| Use the ultrasonic Instrument
to scan all parts of the steam system for the sounds of turbulence. It
will be a reality check to find out how many areas are actually leaking. |
|
| CONCLUSION |
| A maintenance program is critical
in using steam efficiently. Implementing these simple steps can help any
facility realize as much as a 34 percent saving on steam energy costs alone.
Not many investments pay such high dividends. To establish an effective
program, determine the optimum maintenance schedule for each trap and follow
it. It would be difficult to find a less time consuming program that is
as cost effective. |
|
| WARNINGS OF POSSIBLE STEAM TRAP
FAILURE: |
-
An abnormally warm boiler room
-
A condensate receiver is venting excessive
steam
-
A condensate pump water seal Is failing
prematurely
-
The conditioned space is overheating
or under heating
-
Boiler operating pressure is difficult
to maintain
-
Vacuum in return lines is difficult
to maintain
-
Water hammer
|
