Cashco DAP - Manual (Page 9)

IOM-DAP 9
4. Leakage at diaphragm fl ange.
Possible Causes Remedies
A. Body bolts not torqued properly. A. Torque to proper value (see Section VII, paragraph
D-21).
B. Pressures at outlet may be too high for regulator
design.
B. Consult factory.
5. Leakage across seat.
Possible Causes Remedies
A. Contamination (debris) in regulator. A1.
A2.
Remove internals, clean, and if necessary, replace
sealing and seating elements. * Consider fi lter/
strainer.
"Coin" seat if V-TFE or CTFE seat material.
B. Oversized regulator; valve plug operates directly
next to seat.
B. Check actual fl ow conditions; resize regulator for
minimum and maximum fl ow; if necessary, replace
with smaller regulator.
* Excess seat leakage may be diagnosed when a failure of the dynamic balancing side seal or dynamic actuator
seal has oc curred. Inspect all three potential internal leak paths.
6. Dynamic Seal Leakage.
Possible Causes Remedies
A. Contamination (debris) in regulator. A. Remove internals, clean, and if necessary, replace
sealing and seating elements. * Consider fi lter/
strainer.
B. Seal failure. B. Replace both dynamic seals.
C. Seal leakage. C. Seal installed upside down. Remove and reverse
up-down. (Confi rm with drawings).
7. Downstream Pressure too High.
Possible Causes Remedies
A. Seat leakage. A. Replace seat.
B. Dynamic balancing side seal is failing. B. Replace both dynamic seals.
C. Dynamic actuator seal is failing. C. Replace both dynamic seals.