17
Troubleshooting
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 PN-DR, 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. Abnormal
noises
Major causes for the above problems are usage under non-specified conditions (out
of specification), 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 PN-DR Direct-acting Pressure
Reducing Valve” and “Adjustment” sections be reviewed.
Problem Symptom
Cause
Remedy
No steam/air is being supplied
The valve at the primary side
is closed
Check the primary/secondary
piping and valves of the unit
No motive air is being supplied Check motive air supply
The entrance to the screen or
strainer is clogged
Clean or blow down
Flow rate exceeds
specifications
Check the flow rate; check
the model selection, replace
with a more suitable unit if
necessary
The
secondary
pressure does
not rise
Pressure does not
increase
It exceeds the adjustable
pressure range
Check the model selection,
replace with a more suitable
unit if necessary
The flow rate is too low
Check the flow rate; check the
model selection, replace with a
unit that has smaller nominal
diameter or more a suitable
unit if necessary
Pressure fluctuation at the
primary side is large
Check the primary pressure;
check the model selection,
replace with a more suitable
unit if necessary
Buildup on the valve stem
prevents smooth movement
through the spacer
Clean and inspect the valve
stem and spacer
Flow rate fluctuation is too
large
Check the flow rate, re-set
the pressure; check the
model selection, replace with
a more suitable unit if
necessary
The
secondary
pressure
cannot be
adjusted or
increases
abnormally
Adjustment is
difficult and set
pressure varies
The motive air pressure
fluctuates
Check motive air pressure
Troubleshooting continued on next page
172-65119MA-01 (PN-DR) 13 Jun 2013
