Cashco 31-N - Manual (Page 8)

IOM-31-N 8
SECTION VII
VII. SETPOINT ADJUSTMENT/CAL I BRA TION
1. Establish fl ow thru the regulator, preferably a
relatively low fl ow rate, approximately 50 SCFH.
2. Remove closing cap (6) by rotating CCW.
3. If P
2
outlet pressure is less than desired, rotate
ad just ment screw (18) CW; if higher than desired,
rotate ad just ment screw (18) CCW.
4. Reinstall closing cap (6) using pipe joint lubricant/
sealant on threads; fi nger tighten only.
5. Increase fl ow rate to near maximum. Check for
ad e quate P
2
. Repeat Steps 2 thru 4. as required.
NOTE: At higher fl ow rates, removal of the clos-
ing cap (6) can induce an instability. If this occurs,
make adjustment, and quickly replace closing cap
(6), then observe the new setpoint.
SECTION VIII
VIII. TROUBLE SHOOTING GUIDE
Possible Cause Remedy
A. Oversized valve, insuffi cient rangeability. A1.
A2.
Check actual fl ow conditions; consider use of smaller
orifi ce.
Reduce P
1
pressure if possible.
B. Undersized valve, insuffi cient rangeability. B1.
B2.
Check actual fl ow conditions; consider use of larger
orifi ce.
Increase P
1
pressure if possible.
C. High Inlet P
1
pressure. C. Reduce P
1
pressure to 60 psig (4.14 Barg) or lower.
D. Loading ring is “loose”. D. Replace loading ring.
E. Variation of Inlet P
1
pressure. E. P
2
pressure setpoint will vary as P
1
pressure varies;
provide stable P
1
inlet pressure.
F. Dirty service gas; unit becomes unresponsive. F1.
F2. Clean gas stream with liquid separators, strainers, etc.
Disassemble and clean buildup on a routine basis.
G. Downstream over-pressurization. G1.
G2.
G3.
G4.
G5.
G6.
Install safety relief valve or rupture disc with a 50 psig
(3.45 Barg) setting or lower.
Disassemble actuator assembly and check for bent
upper diaphragm plate. Check for relief cap distortion.
Flow is tightly shutoff downstream of regulator;
relocate shutoff valve.
Seat leakage; replace seat.
Failure of orifi ce thread sealant; reinstall orifi ce.
Correct process conditions/controls that cause P
2
pressure to become greater than 50 psig (3.45 Barg).
H. Process pressure pulsations – inlet or outlet. H1.
H2. Stabilize process pressures at source or end use.
Install volume tanks to reduce pulsation effects.
J. Adjustment screw loosening, P
2
outlet pressure
decreasing.
J1.
J2. Place locking compound on threads of adjustment
screw.
Stabilize fl ow to reduce vibrations.
1. Variation in outlet P
2
pressure.