LowFlow JB Series Back Pressure Regulators - Manual (Page 3)

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C. Diaphragm Replacement
Caution! To prevent damage to body, use soft
jaws when placing the body in a vise. Position
so that vise closes over the flats on lower end of
body.
1. Perform Steps 1 - 6 from Section B, Trim
Replacement.
2. Perform steps 9-11 from Section B, Trim
Replacement.
Troubleshooting
1. Erratic Operation; Chattering
A. Oversize regulator; inadequate rangeability
1. Check actuator flow conditions, re-size
regulator for minimum and maximum flow.
2. Increase flow rate.
3. Install next step higher range spring.
Before
replacing regulator, contact factory
B. Worn plug or seat; inadequate guiding
1. Replace trim (possible body replacement)
C. Valve is stuck in position.
1. Determine if corrosion is causing plug to
not move freely. Clean or replace parts as
necessary.
2. Regulator can’t pass sufficient flow
A. Regulator not closing tightly
1. Inspect tip of lower diaphragm plate (4)
and seat assembly(2), replace if worn.
B. Downstream blockage
1. Check system; isolate (block flow at
regulator inlet - not outlet.
2. Relocate regulator if necessary
C. No pressure relief protection
1. Install safety relief valve, or rupture disc.
D. Restricted diaphragm movement
1. Ensure there are no obstructions in the
vent hole of the spring housing (7), and
check for icing on the spring.