8 | Baker Hughes
Copyright 2023 Baker Hughes Company. All rights reserved.
Supply
Pressure
(psig)
Cylinder Bore (in.)
4
5
6
8
10
12
14
Variable Orifice Number
Up to 50
3
3
3
4
4
5
6
51-200
2
2
3
3
4
5
5
201-600
2
2
2
3
3
4
5
Note:
For VRP-CH equipped with VB series volume boost
-
ers, set variable orifices between number 1 and 2 regardless
of the cylinder size. Steady state gas consumption is mini
-
mized at 1. For additional information on VB series volume
boosters refer to the Accessories section of this manual.
3. Disable PS-2 series non-bleed sensor (if equipped):
The PS-2 non-bleed sensor should be disabled prior to
commencing initial adjustment procedures. Failure to
disable the sensor may prevent the proper completion of
initial adjustments. To disable the PS-2 series non-bleed
sensor, rotate the adjustment screw of the PS-2 clockwise
until it extends approximately 1.75-inch from the top surface
of the PS-2 spring cartridge.
4. Disable AB series atmospheric bleed control (if equipped):
The AB series atmospheric bleed control should be disabled
prior to commencing initial adjustment procedures. Failure
to disable the control may prevent the proper completion
of initial adjustments. To disable the AB control, rotate
the adjustment screw of the AB control counterclockwise
until it disengages. Then, tighten the nut on the AB sensor
adjustment screw to seal threads on the cap.
5. Close cylinder block valves: Closing the cylinder block
valves will isolate the VRP-CH from the control valve
actuator. This prevents unintended stroking of the control
valve and simplifies setting the VRP-CH.
6. Close the valve on the sensing line: A shutoff valve must
be installed as close to the sensing port of the VRP-CH
as possible. The volume of gas between the VRP-CH
sensing port and the block valve on the sensing line should
be minimized. It is also imperative that the fittings between
the VRP-CH sensing port and the sensing line block valve
be bubble tight to facilitate adjustment. It is recommended
that a quarter-turn (locking) ball valve be used to isolate the
VRP-CH sensing line. Confirm that the VRP-CH exhaust
(discharge) line is open. The discharge line is connected to
the port marked “EX”. Should flow from the exhaust port be
blocked, adjustment of the VRP-CH will not be possible.
7. Apply a “False Signal” to the sensing port of the VRP-CH:
The “False Signal” pressure should be equivalent to the
desired setpoint pressure. Refer to the original invoice
paperwork supplied with the product for the appropriate
setpoint pressure setting. If the adequate gas pressure
is not available from the pipeline, a nitrogen bottle with
regulator may be used to introduce the proper “False Signal”
pressure. Additionally, an SP series setpoint adjustment
pump may be used to provide a “False Signal” pressure
above the available pipeline gas pressure.
Note:
It is recommended that a calibrated pressure gauge
be used to help ensure accuracy of the “False Signal”
pressure.
WARNING: DO NOT turn the sensitivity adjustment
drum without first applying a sensing pressure and
initial spring tension on the adjusting screw. If these
forces are not present, one of the two pilot seats will
be “cut” on the internal nozzle due to the pressure
between the seat and nozzle.
8. Initialize the sensitivity adjustment:
Turn the sensitivity adjustment drum to the right (decreasing
numbers on the scale) as far as it will turn. Then turn it one
(1) complete rotation to the left (increasing numbers on the
scale).
9. Adjust the setpoint adjustment screw:
Turn the setpoint adjustment screw on top of the VRP-CH
unit until cylinder top and cylinder bottom pressure gauges
show equal pressure. Clockwise rotation increases cylinder
top pressure. Turn setpoint adjustment only when pressures
are not equal.
10. Final sensitivity drum adjustment:
Turn the sensitivity adjustment to set the cylinder top and
cylinder bottom at the proper cylinder balance pressure
(P
c
) See (see Equations 1 and 2 below). Turn sensitivity
adjustment to the right (decreasing numbers on the scale)
to increase the cylinder top and cylinder bottom pressures.
Turn sensitivity adjustment to the left (increasing numbers
on the scale) to decrease the cylinder top and cylinder
bottom pressures.
The correct cylinder balance pressure (P
c
) is found using the
cylinder balance pressure equations:
VRP-CH Discharge to PRESSURE SYSTEM
(NO Volume Boosters)
P
c
= P
d
+ [0.4*(P
s
- P
d
)] (Equation 1.a)
VRP-CH Discharge to ATMOSPHERE
(NO Volume Boosters)
P
c
= 0.4*P
s
(Equation 1.b)
VRP-CH Discharge to PRESSURE SYSTEM
(EQUIPPED with Volume Boosters)
P
c
= P
d
+ [0.2*(P
s
- P
d
)] (Equation 2.a)
VRP-CH Discharge to ATMOSPHERE
(EQUIPPED with Volume Boosters)
P
c
= 0.20*P
s
(Equation 2.b)
Variables:
P
c
= Cylinder balance pressure (psig)
P
d
= Discharge pressure (psig)
P
s
= Power gas (supply) pressure
11. Typically, only one of the cylinder output gauges will respond
at first. Continue rotating sensitivity adjustment until at least
one of the gauges indicates a pressure equivalent to the
proper cylinder balance pressure (P
c
).
12. At this point, rotate the setpoint adjustment to equalize
cylinder top and cylinder bottom pressures. Repeat Steps
10 and 11 until the proper cylinder output pressures are
achieved. As the VRP-CH nears the proper adjustment,
both cylinder top and cylinder bottom gauges will respond
simultaneously when the sensitivity drum is turned.
VRP-CH setpoint is achieved when both cylinder top and
cylinder bottom equalize at a pressure equivalent to the
proper cylinder balance pressure (P
c
).
13. Verify “False Signal”:
2. Set the orifice per table below.
