LowFlow JBDL Series Back Pressure Valves - Manual (Page 3)

Troubleshooting
If You Experience Erratic Control:
• Regulator may be oversized. Oversizing causes
cycling and hunting, and reduces the rangeability
of the valve - make certain that your valve has been
correctly sized according to your application condi-
tions.
• Valve seat (10) may be defective - replace seat
holder (11) and soft seat (10).
• Valve plug (12) may not be moving freely - inspect
the diaphragm assembly.
• Weakened/broken return spring (13) - Determine
if corrosion is causing plug (12) to not move freely.
Replace return spring (13).
If You Experience Upstream Pressure Build-up or In-
ability to Maintain Regulated Pressure:
• Inspect for jamming between upper diaphragm plate
(6) and spring housing (2).
• Diaphragm (8) may have failed - replace as neces-
sary.
• Piping may be blocked or undersized.
• Range Spring (4) may be set too high or may be bro-
ken - inspect and reset or replace as necessary.
• The valve may be undersized for required flow -
make certain that the valve has been sized correctly.
If the Regulator can’t pass sufficient flow:
A. Downstream blockage
1.
Check system; isolate (block flow at regulator
inlet, not outlet).
2. Relocate regulator if necessary
B. No pressure relief protection
1. Install safety relief valve, or rupture disc.
C. Restricted diaphragm movement
1. Ensure there are no obstructions in the vent
hole of the spring housing (2), and check for
icing on the spring.
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