Cashco 1000 Cryogenic - Manual (Page 9)

IOM-1000HP-Cryogenic 9
SECTION VII
VII. TROUBLE SHOOTING GUIDE
Possible Causes Remedies
A. Oversized regulator; inadequate rangeability. A1.
A2.
A3.
A4.
Check actual fl ow conditions, resize regulator for minimum and
maximum fl ow.
Increase fl ow rate.
Decrease regulator pressure drop; decrease inlet pressure by
placing a throttling orifi ce in inlet piping union.
Replace full orifi ce with reduced orifi ce; i.e. new cylinder required.
B. Worn piston/cylinder; inadequate guiding. B. Replace trim.
C. Flow induced instability. C1.
C2.
C3.
Get straight runs of piping (5 diameters upstream, 10 downstream)
to and from valve.
Ensure outlet velocity is not excessive; use pipe reducer close to
valve outlet.
Add next higher range spring.
D. Improper (oversized) jet. D. Replace existing piston with new piston with proper jet.
E. Plugged trim. E. Remove trim and check for plugged holes in piston, or debris in
guide zone or jet zone.
1. Erratic operation; chattering.
Possible Causes Remedies
A. Setpoint too low. A. Turn adjusting screw down (CW) to increase setpoint.
B. Regulator undersized. B1.
B2 Confi rm by opening bypass valve together with regulator.
Check actual fl ow conditions, resize and if regulator has inadequate
capacity, replace with larger unit.
C. Plugged inlet strainer. C. Remove strainer screen and clean; consider leaving screen out.
D. Plugged trim. D. Remove trim and check for plugged holes in piston, or debris in
guide zone or jet zone.
E. Incorrect range spring (turning adjusting screw
CW does not allow bringing pressure level up to
proper level). E. Replace range spring with proper higher range.
F. Too much proportional band (droop). F1.
F2.
F3. Review P.B. (droop) expected. (See 2.B1 above.)
Diaphragm setting too low; check and raise as required.
Improper jet; make sure jet matches actual fl uid.
G. Restricted diaphragm movement. (pressure plate
hitting upstops)
G1.
G2. Diaphragm setting too high; check and lower as required.
Ensure no moisture in spring chamber at temperatures below freeze
point. Ensure no dust or debris entering vent opening. If rainwater
or debris can enter, re-orient spring chamber.
H. Restricted diaphragm movement. (over-stretched
diaphragm)
H1.
H2.
H3.
Diaphragm setting too low; check and increase as required.
Ensure no moisture in spring chamber at temperatures below freeze
point. Ensure no dust or debris entering vent opening. If rainwater
or debris can enter, re-orient spring chamber.
Ensure drain opening is clear of blockage.
2. Regulator outlet (downstream) pressure too low.
Possible Causes Remedies
A. Normal-life diaphragm failure. A. Replace diaphragm.
B. Abnormal short-life diaphragm failure. B1.
B2.
B3.
Can be caused by excessive chattering. See No. 1 to remedy valve
chatter.
Can be caused by corrosive action. Consider alternate diaphragm
material, or Option 1000-9, TFE diaphragm cover.
Downstream (outlet) pressure buildup occuring that overstresses
diaphragms.
C. Pusher plate gasket leaking. C. Replace gasket.
3. Leakage through the spring chamber vent hole.