IM-P186-03 CH Issue 4
14
6. Fault finding
Before investigating any fault ensure that both upstream and downstream isolating valves
are shut off and that the SRV2S is vented.
SYMPTOM Downstream pressure increases above set pressure.
CAUSE 1 Bellows failure or bellows leakage.
CHECK and CURE Replace bellows set. Check valve is not subject to rapid oscillation causing
bellows fatigue failure.
CAUSE 2 Damage or erosion to valve seat.
CHECK and CURE Replace valve and seat assembly.
CAUSE 3 Excessive dirt /
scale build up on seat and head, blocked pressure.
sensing orifice/sticking pushrod.
CHECK and CURE Replace valve and seat assembly.
SYMPTOM
Downstream pressure is below set pressure under
full load conditions.
CAUSE 4 Valve was set at 'No-load'.
CHECK and CURE Reset at full load (Refer to start-up and adjustment, Section 3).
CAUSE 5 Valve is undersized for required duty.
CHECK and CURE Check maximum installed load and valve size selected and installed.
SYMPTOM Adjustment knob will not turn.
CAUSE 6 Tamper-proof pin is preventing adjustment.
CHECK and CURE Remove pin from cap.
SYMPTOM Hunting/unstable control.
CAUSE 7 Wet steam.
CHECK and CURE Ensure lines are properly trapped, install separator if necessary.
CAUSE 8 Externally transmitted signals.
CHECK and CURE Check proximity of valve to other associated control equipment e.g.
on /off valves.
CAUSE 9 Sticking pushrod due to dirt / scale build up.
CHECK and CURE Replace valve and seat assembly.
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