172-65175MA-13 (COS Pressure Reducing Valve) 16 Feb 2022
25
Troubleshooting
NEVER apply direct heat to the float. The float may explode due to
increased internal pressure, causing accidents leading to serious injury
or damage to property and equipment.
WARNING
When disassembling or removing the product, wait until the internal
pressure equals atmospheric pressure and the surface of the product
has cooled to room temperature. Disassembling or removing the
product when it is hot or under pressure may lead to discharge of fluids,
causing burns, other injuries or damage.
CAUTION
This product is shipped after stringent checks and inspection and should perform its
intended function for a long period of time without failure. However, should there be
any problem encountered in the operation of the COS, consult the troubleshooting
guide below.
Problems are classified as follows:
1. The secondary pressure does not increase.
2. The secondary pressure cannot be adjusted or increases abnormally.
3. Hunting (fluctuation of the secondary pressure) occurs.
4. Chattering (a heavy mechanical noise) occurs.
5. Steam leaks from the steam trap or condensate is not discharged.
6. Abnormal noises.
Major causes for the above problems are usage under non-specified conditions (out
of specifications), insufficient pressure or flow rate, and clogs by dirt and scale.
To ensure performance for a long period of time, it is recommended that the
“Acceptable Operating Range”, “Correct Usage of the COS Reducing Valve” and
“Adjustment” sections be reviewed
.
It is a recommended practice to dismantle and inspect the product once a year for
preventive maintenance purposes. It is especially important to perform an inspection
immediately after the initial run of a new line or before or after equipment such as a
heater is out of service for a long period of time.
Problem
Symptom
Cause
Remedy
The secondary
pressure does
not rise
The COS body is
not warm
No steam is being
supplied or the inlet
valve is closed
Check the valves and
piping
The body is warm,
but the pressure
does not increase
The entrance to the
screens or strainer is
clogged
Clean or blow down
The secondary
pressure
cannot be
adjusted or
increases
abnormally
Adjustment is
difficult, and set
pressure varies
The pilot screen is clogged Clean
There is insufficient
steam flow
Check the flow, replace
the COS if necessary
The piston is clogged
with dirt
Clean
Check the piston ring
The piston ring is worn
Replace with a new
piston ring
There is a build-up of dirt
on the sliding surfaces of
the pilot, piston or main
valve
Clean
Continued on the next page
