Jordan Valve Mark 6127 Series Pressure Reducing Valves - Manual (Page 3)

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10. Slowly turn the adjusting screw of the pressure-
reducing pilot counterclockwise until
downstream pressure decreases to the desired
set point. Tighten the adjusting screw jam nut
and replace the plastic cap.
11. If there are small-scale oscillations in the down
stream pressure, slowly turn the adjusting screw
of the flow control valve clockwise until the oscil-
lations disappear. CAUTION: Never close this
valve fully. To do so will prevent the main
valve from opening.
12. If pressure readjustment should ever be re-
quired, the pressure-reducing pilot is
adjusted clockwise to increase pressure;
counterclockwise to decrease pressure.
M
aIntenance
Due to the simplicity of design of the 6127, required
maintenance is minimal. However, the following
checks, periodically performed, will do much to keep
the valve operating properly and efficiently.
1. Check for chipped or peeling paint.
2. Check for leaks at fittings and around flanges
and connections. Tighten as required.
3. If the valve is equipped with a Y-strainer, check
the screen for buildup of solid material. Clean
as required. This point is most important, as a
clogged strainer can keep the valve from oper-
ating properly. On new installations, it is
recommended that the strainer be checked
everyday or two until experience dictates a
greater or lesser interval.
t
roubleshootIng
In the event of malfunction of the Mark 6127, the
following guide should enable the technician to
isolate the specific cause of the problem and take the
appropriate corrective action.
A. MAIN VALVE FAILS TO OPEN:
1. Valve closed downstream of 6127. Open as
required.
2. Downstream pilot system ball valve closed.
Open as required.
3. Flow control valve fully closed. See Adjustment
instructions.
4. Pressure-reducing pilot adjusted too far counter-
clockwise. See Adjustment instructions.
5. Pressure-sustaining pilot adjusted too far clock
wise. See Adjustment instructions.
6. Stem of pressure-reducing pilot binding.
7. Diaphragm of pressure-sustaining pilot ruptured.
This will be evidenced by a discharge of
fluid from the vent hole in the pilot bonnet.
Disassemble pilot and replace diaphragm.
8. Stem of pressure-sustaining pilot binding.
9. Stem of main valve binding.
B. MAIN VALVE FAILS TO CLOSE:
1. Upstream pilot system ball valve closed. Open
as required.
2. Strainer clogged. Clean as required.
3. Pressure-reducing pilot adjusted too far clock
wise. See Adjustment instructions.
4. Diaphragm of pressure-reducing pilot ruptured.
This will be evidenced by a discharge of fluid
from the vent port in the pilot bonnet. Disassem-
ble pilot and replace diaphragm.
5. Close downstream pilot system ball valve.
a. If main valve closes, proceed to Step 6.
b. If main valve remains open, proceed to
Step 7.
6. Pressure-reducing pilot stem binding or seat
badly deteriorated. Disassemble pilot and deter
mine cause.
7. Close both pilot system ball valves, and loosen
a pipe plug in the main valve bonnet. A continu-
ous discharge of fluid from the loosened
plug indicates that the main valve diaphragm is
ruptured. SEE NOTE BELOW.
8. Main valve stem binding or object in valve.
Disassemble valve and determine cause.
NOTE: Certain valves, predominantly those in fuel
service, are assembled "fail closed." In this case, a
ruptured diaphragm would keep the valve from opening,
rather than keep it from closing. To determine
which type you have, examine the bridge mark cast
into the side of the main valve body. If the bridge mark
slants downward on the upstream end, the valve is
"fail closed." If the bridge mark slants upward on the
upstream end, the valve is "fail open."
M
ark
6127 S
erieS
P
reSSure
r
educing
V
alVe