Cashco DA6 - Manual (Page 13)

IOM-DA6 13
4. Diaphragm continually breaks (steam service regulators).
Possible Causes Remedies
A. Stem seals (14) which protect A. Replace with new stem seals (14).
fl uorocarbon elastomer in diaphragm
assembly may have deteriorated.
B. Diaphragm nut (7) may not be B. Confi rm torque value in accordance with Section VII,
torqued to proper value. paragraph E-13.
C. Diaphragm too stiff causing it C. Follow proper preforming and air evacuation techniques
to crack in service. during diaphragm installation in accordance with Section VII,
paragraph F-10.
5. Diaphragm continually breaks (all regulators).
Possible Causes Remedies
A. Differential pressure across dia- A1. Be aware of limits as well as where the various pressures
phragm may have exceeded limits. are acting. Install pressure safety equipment as necessary.
(See Table 1 in Tech Bulletin A2. Consider if full diaphragm support, Opt-81, should be added.
DA6-TB.)
6. Leakage at diaphragm fl ange.
Possible Causes Remedies
A. Body bolts not torqued properly. A. Torque to proper value (see Section VII, paragraph F-11).
B. Pressures at diaphragm may be B. Consult factory.
too high for regulator design.
7. Leakage across seat.
Possible Causes Remedies
A. Contamination (debris) in regulator. A. Remove internals, clean, and if necessary, replace
sealing and seating elements. *
B. Oversized regulator; valve plug B. Check actual fl ow conditions; resize regulator for minimum
operates directly next to seat. 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
potential internal leak paths.