Cashco 5100 - Manual (Page 10)

10 IOM-5100
SECTION IX
Pilot Valve Test Stand
IX. PRESSURE CALIBRATION AND
TESTING PROCEDURE FOR PILOT:
1. To determine set pressure, slowly increase
the pilot inlet pressure. Simulated actuator
pressure will rise with inlet. As set pressure
is approached, the actuator pressure will be-
gin to decrease. Continue to increase the
inlet pressure slowly until the actuator pres-
sure is 90% (+/- 10%) of the inlet pressure.
This is the set pressure.
2. Rotate the set pressure adjusting screw
(213) CW to increase set pressure or CCW
to decrease set pressure. Continue to rotate
the adjusting screw and repeat the test per
Step 1 previous until the speciſ ed set pres-
sure is achieved.
3. To determine reseat pressure, slowly de-
crease the inlet pressure and the actuator
pressure will begin to increase. Reseat oc-
curs when the actuator pressure equal the
inlet pressure.
4. The difference between set and reseat
pressure,”blowdown”, can be adjusted with
the blowdown needle (217). Maximum
clockwise rotation provides rapid relief valve
opening, “snap action”’ and maximum blow-
down. Standard blowdown, unless other-
wise speciſ ed is 7 - 10% below set pressure.
5. Increased counter clockwise rotation of
blowdown screw provides “modulating” ac-
tion and minimum (zero) blowdown. Reseat
pressure is the same as set pressure.
NOTE: The blowdown needle is located
in a pressure containing chamber, and is
retained by the blowdown o-ring (218) and
blowdown locknut (236). DO NOT remove
the blowdown needle while under pressure.
6. Remove body vent and install a ƀ exible tube
in this port. Immerse this pilot discharge
bubble tube in water approximately 1/4” be-
low surface to detect cracking and reseat
pressure.
7. A small interaction occurs between set
pressure and blowdown adjustments. Re-
adjustment of both may be required until
the speciſ ed set pressure and blowdown
are achieved. After completion, lock both
screws and locknuts and replace closing cap
(205) on adjusting screw (213).
8. Hold the valve at the set pressure while
preforming a soap bubble test of all bolted,
ƀ anged and threaded connections.
9. Refer to Table 3 for standard setting Speciſ -
cations.
TABLE 3
SETTING SPECIFICATIONS - PILOT VALVE
Pilot Action
Set
Pressure
Set
Pressure
Limits
Maximum
Cracking
Pressure %
of Set
Reseat
Pressure
% of Set
Snap 2” - 8” WC +/- 0.2”WC 75 90 +/- 3
Snap
8.1” WC -
1.0 psig
+/- 3% 90 90 +/- 3
Snap
1.1 - 15.0
psig
+/- 3% 95 93 +/- 3
Modulating 2” - 8” WC +/- 0.2” WC 75 100
Modulating
8.1” - 1.0
psig
+/- 3% 90 100
Modulating
1.1 - 15.0
psig
+/- 3% 95 100