6
Troubleshooting
(Refer to Figs. 6, 7 and 8)
Symptom Cause Check and Cure
1. Controlled pressure over- 1. (a) Dirt or foreign material between pilot 1. (a) Loosen screw (2D). Remove copper
shoots under normal valve seat and head. tubing connections at (J & L). With
load conditions steam on valve, if steam flows from
copper tubing connections at (J & L)
remove pilot head and seat assembly
(2H) and clean or replace.
(b) Foreign particles between main valve (b) Inspect and clean head and seat
head and seat.
(c) Orifices (B) and (H) or pressure sensing (c) Remove, inspect and clean.
line may be plugged.
2. Controlled pressure 2. (a) Main valve head and seat worn or dirt 2. (a) Inspect and clean head and seat.
overshoots only on between them.
light loads.
(b) Valve may be severely oversized. (b) Adjust screw (2D) to give desired
pressure under light loads.
(c) Bypass valve not shut tightly or leaking. (c) Check and repair as required.
(d) Dirt or foreign material on main valve (d) Remove, inspect and clean.
stem and guide (1F).
3. Valve fails to open. 3. (a) Main valve diaphragm ruptured. 3. (a) Unscrew copper tubing connection at
(G) and crack bypass valve. If steam
flows from main valve diaphragm
case, diaphragm is defective and
must be replaced.
(b) Orifice (H) is plugged (b) Remove and clean.
(c) Pilot valve seat is plugged with dirt. (c) Remove head and seat assembly
(2H). Inspect and clean or replace.
(d) Screen (1D) is plugged. (d) Inspect screen and clean.
(e) Pipeline strainer blocked. (e) Inspect and clean.
(f) Pilot valve adjustment (2D) or air loading (f) Adjust screw (2D) to desired pres-
pressure not properly adjusted. sure. Check air supply to PA pilots.
4. Delivery pressure low. 4. (a) Pilot valve adjustment (2D) not 4. (a) Adjustment screw (2D) to desired
properly adjusted. pressure.
(b) Valve undersized. (b) Check actual load against valve
rating.
(c) Steam supply pressure too low. (c) Check and correct.
(d) Main valve diaphragm ruptured. (d) Unscrew copper tubing connection
(G) and crack bypass valve. If steam
flows from diaphragm case, dia-
phragm is defective and must be
replaced.
(e) Bleed orifice (B) missing. (e) Replace proper fitting.
5. Valve fails to close. 5. (a) Bypass valve open or leaking. 5. (a) Check and repair as required.
(b) Pilot sensing line blocked (b) Remove, inspect, clean or install.
(or not installed).
(c) Pilot ruptured (water or steam coming (c) Replace pilot diaphragm assembly.
from pilot at spring retainer area).
(d) Pilot assembly or main valve seat (d) Check casting in seat area for
threads leaking. erosion.
(e) Main valve diaphragm reassembled (e) With main valve cover installed,
without return spring and main valve loosen all main valve diaphragm
cover holding valve head closed. bolts (1C) and then retighten.
(1/2” thru 4” sizes only).
To Next Page
Loading...
Need help?
General
