Cashco 1000 HP Differential - Manual (Page 11)

11 IOM-1000HP-Dif fer en tial
4. Excessive pressure downstream.
Possible Causes Remedies
A. Regulator not closing tightly. A1. Overly compressed range spring; i.e. approaching
solid height. Use next higher range spring.
A2. Inspect the seating. Clean and lap metal seat
surfaces; replace if lapping does not remedy. If
composition seats are depressed, nicked or
embedded with debris, replace seat disk.
A3. Diaphragm setting too high; check setting.
A4. Inlet pressure too high for orifi ce size; check
permissible inlet (P
1
) pressure level for a given
outlet. Change to reduced port if required.
A5. Leakage past pressed in seat ring; consider
integral seat.
A6. When diaphragm subassembly was put into place,
the rocker arm got between the stud collar and the
stud nut rather than on top of the stud collar.
B. Downstream block. B. Check system; isolate (block) fl ow at regulator
inlet, not outlet. Relocate regulator if necessary.
C. No pressure relief protection. C. Install safety relief valve, or rupture disc.
D. Restricted diaphragm movement. D1. Diaphragm setting too high; check and lower
as required.
D2. Ensure no moisture in spacer ring at temperatures
below freeze point. Ensure no dust or debris
entering vent opening. If rainwater or debris can
enter, reorient spring chamber. (Not possible on
-1+6.)
5. Sluggish operation.
Possible Causes Remedies
A. Plugged piston or jet zone. A. Remove trim and clean.
B. Fluid too viscous. B. Heat fl uid.
C. Improper (undersized) jet. C. Replace existing piston with new piston for
viscous service; i.e. Opt-27.
6. Frequent resetting of setpoint.
Possible Causes Remedies
A. Overpressurization downstream resulting in: A1. Replace diaphragms. Correct potential source of
1. Bent metal diaphragm(s) downstream overpressure.
2. Sprung rocker arm A2. Check measurements of rocker arm. Replace if
3. Range spring overstressed/fatigued. necessary.
A3. Replace range spring; consider next higher range
spring.