Cashco DA1 - Manual (Page 13)

13 IOM-DA1
3. Downstream pressure will not reach desired setting.
4. Diaphragm continually breaks (steam service regulators).
5. Diaphragm continually breaks (all regulators).
6. Leakage at diaphragm fl ange.
7. Leakage across seat.
Possible Causes Remedies
A. Stem seals (14) which protect fl uorocarbon elastomer
in diaphragm assembly may have deteriorated.
A. replace with new stem seals (14).
B. Diaphragm nut (7) may not be torqued to proper value.
B. Confi rm torque value in accordance with Section
VI paragraph F-7.
C. Diaphragm too stiff causing it to crack in service.
C. Follow proper preforming and air evacuation tech
niques during diaphragm installation in accordance
with Section VI, paragraph F-13.
Possible Causes Remedies
A. Supply pressure is down (confi rm on pressure gauge.) A. Increase supply pressure.
B. Undersized regulator.
B. Check actual fl ow conditions; resize regulator for
minimum and maximum fl ow; if necessary, replace
with larger regulator.
Possible Causes Remedies
A. Differential pressure across diaphragm may have
exceeded limits. (See Table 4 in Tech Bulletin DA1-TB.
A. Be aware of limits as well as where the varioius
pressures are acting. Install pressure safety equip-
ment as necessary.
Possible Causes Remedies
A. Body bolts not torqued properly.
A. Torque to proper value (see Section VI, paragraph
F-14)
B. Pressure at diaphragm may be too high for regulator
design.
B. Consult factory.
Possible Causes Remedies
A. Contamination (debris) in regulator.
A1. Remove internals, clean, and if necessary, re-
place sealing and seating elements.*
A2. "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 side seal has occurred. Inspect both poten-
tial internal leak paths.