Samson 42-34 Mounting And Operating Instructions page 50

Malfunctions
Table 9: Troubleshooting
Malfunction
Flow rate or differential
pressure exceeds adjusted set
point
Flow or differential pressure
set point not reached
Control loop hunts.
50
Possible reasons
Leak between seat and plug
Defective operating diaphragm
Control line blocked
Valve too large for control task (flow
rate) or too small (differential pressure)
Incorrect set point range selected.
Safety device, e.g. pressure limiter, has
been triggered.
Plant differential pressure Δp too low
Strainer blocked
Incorrectly installed valve (direction of
flow).
Defective operating diaphragm
Valve too large for control task
The restriction (or needle valve) in the
control line for pressure tapping is
missing.
Recommended action
Remove valve from the pipeline and clean
seat and plug. Replace the plug, if
possible. If this is not possible, return
regulator to SAMSON for repair.
Replace operating diaphragm or return
regulator to SAMSON for repair.
Remove control line and clean it.
Recalculate K and contact SAMSON for
VS
further action.
Check set point range and contact
SAMSON for further action.
Check plant. Unlock safety device.
Compare differential pressure in the
plant with the plant's drag.
Plant differential pressure
∆p = ∆p + (V/K
min restriction
Drain and clean filter of the strainer.
Install the valve in such a way that the
flow of direction corresponds with the
direction indicated by the arrow on the
valve body.
Replace operating diaphragm or return
regulator to SAMSON for repair.
Recalculate K and contact SAMSON.
VS
Install a needle valve into the control line
and start to close the needle valve until
the control loop becomes stable.
NOTICE Do not completely close the
needle valve.
.
)²
VS
EB 3013 EN