PHODS Technical Manual
16
SYMPTOM
POSSIBLE CAUSE
TREATMENT
System will not remain depressurized
after handwheel is closed and system is
purged.
1. The seat & disc retainer (11) is worn or
damaged.
1. Replace seat & disc retainer
2. The seat & disc retainer crown in first stage
body (8) is worn or damaged.
2. Replace body
High or Unstable MP “Creep”
1. The seat & disc retainer (11) is worn or
damaged.
1. Replace seat & disc retainer
2. The seat & disc retainer crown in first stage
body (8) is worn or damaged.
2. Replace body
3. The spring (7) is weakened or damaged.
3. Replace spring
4. The HP seat (6) is worn or damaged.
4. Replace HP seat
5. The HP crown seating surface in first stage
body (8) is worn or damaged.
5. Replace body
Low MP
1. The spring (7) is weakened or damaged.
1. Replace spring
External Oxygen Leak
1. The piston head o-ring (3) or shaft o-ring
(5) is worn or damaged.
1. Replace o-rings
2. The o-ring grooves on the piston (4) are
worn or damaged.
2. Replace piston and o-rings
3. The piston head o-ring sealing surface in the
retainer cap (2) is worn or damaged.
3. Replace retainer cap
4. The piston shaft o-ring sealing surface in
the first stage body (8) is worn or damaged.
4. Replace first stage body
CPC Connector Leaks
1. Teflon tape on CPC connector (9) worn or
damaged.
1. Replace Teflon tape on CPC connector
TABLE 1: TROUBLESHOOTING GUIDE FIRST STAGE
