Cashco 9540L P-P User Manual
INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)
MODEL 9540L
P/P - PNEUMATIC POSITIONER FOR LINEAR VALVES
I. DESCRIPTION AND SCOPE
Model 9540L is a single acting, compact, force balance, pneumatic positioner used on linear travel (sliding stem) control valves. This positioner is utilized to
linearize the relationship between valve stem position
and the system’s control signal. This design is only
suitable for nominal 3-15 psig input signals, or split
range variations thereof.
Each unit comes complete with a set of built-in gages
within the internals; the cover includes a clear see-thru
panel to monitor gages. Gages monitor input “SIG”
and output “LOAD”.
IOM-9540L
06-99
SECTION I
The Model 9540L P/P positioner may be utilized with
the following current Cashco product models:
987 964 520 TFE SCV-30
988 2266 (2” size) 521 TFE
989 2296 SCV-S
PCV
5-13 psig
LOAD
3-15 psig
DIR.
P/P
P1 = 500 psig
Figure 1: Typical Pressure Reducing Pneumatic Control
ATO-FC
Loop - PCV with P/P Positioner
IAS
SIG
15-3 psig
PC
REV.
PROCESS
P2 = 100 psig
IAS
20 psig
IAS - Instrument Air Supply
PC - Pressure Controller
PCV - Pressure Control Valve
ATO-FC - Air-to-Open, Fail Close
ATC-FO - Air-to-Close, Fail Open
P/P - Pneumatic Input/Pneumatic Output
DIR - Direct Acting
REV - Reverse Acting
SIG - Controller Output Signal
V - Vent
CW - Clockwise rotation
CCW - Counter-clockwise rotation
SECTION II
II. METHOD OF OPERATION (See Figure 2)
The positioner operates with the force balance
principle: the input signal “SIG” (3-15 psig) acts on the
input diaphragm (50).The stroke of the input diaphragm is transferred to the flapper lever (38). The
resulting movement of the flapper varies the dynamic
pressure at the nozzle (51). This pressure acts on the
amplifier (53) and the change in output pressure
causes a movement of the actuator/valve stem.
This movement is back fed from the actuator/valve
stem (55) by the feedback lever (13) of the positioner,
and transferred to the stroke factor lever (19). The
stroke factor lever (19) is connected to the flapper
lever (38) by means of a range spring (41).
A force balance is created on the flapper lever (38)
when the force generated by the input diaphragm (50)
balances with the counter-force produced on the range
spring (41). This ensures that the actuator/valve stem
position is always proportional to the input signal.
Dynamic matching of the actuator (sensitivity, stability)
is factory set by means of the throttle screw (42) and
the damping throttles (44). The stroke range and zero
are set by means of the stroke factor thumbscrew (40)
and the zero thumbscrew (39). The changeover plate
(15) is used to set either an increasing or decreasing
output pressure for an increasing input signal, i.e.
direct or reverse acting.
The normal factory set position of the bypass switch (3)
is “EIN” (ON) (pointer at 6 o'clock), and the positioner
will be operational. If the positioner bypass switch (3)
is set to the “AUS” (OFF) position (pointer at 9 o’clock),
the input signal SIG is supplied direct to the actuator;
i.e. the positioner has no effect. Operation in the “AUS”
(OFF) position is only practical for control valves where
the positioner action is “Direct” and the actuator bench
range is approximately equal to the 3-15 psig “SIG”.
Use of bench ranges with upper limits greater than 15
psig will cause the control valve to not be able to fully
stroke when bypassed.
3
SIG
55
Travel
Figure 2: Single-acting positioner functional diagram.
On
LOAD
50
38
13
41
51
52
NU
15
19
44
53
IAS
42
39
40
III. MOUNTING TO SPRING DIAPHRAGM
ACTUATORS
A. The following text applies to field mounting of a
positioner.
B. Determining Mounting Side:
1. The action/failure position on the control valve
unitmust be known “Air-to-Open, Fail Closed”
(ATO-FC); or “Air-to-Close, Fail Open” (ATCFO). The mounting side is selected from Table
1 considering:
a.) Valve action/failure position
b.) Stem travel direction with increasing “SIG”
c.) Positioner action - Direct or Reverse
(Choose either steps 2a. -to- 3a.; or choose
steps 2b. -to- 3b.)
2a. On actuator yokes with a cast-on rib located
on one of the legs that support the lower
diaphragm housing, see representative crosssection Figure 3A. Rotate the actuator until
the rib with its mounting taps is located on the
side (right or left) as indicated in Table 1.
(Includes 987’s, 964’s and 2” 2266’s, 520 &
SECTION III
521 TFE’s with Models 55D, 55R, 115D and
115R actuators).
2b. The actuator yokes without a cast-on rib will
have four mounting holes on one of the yoke’s
legs. (See representative cross-section Figure 3B.) Rotate the actuator until the leg with
the four holes is on the side (right or left) as
indicated Table 1. (Includes 520 & 521 TFE’s
with Model 30 actuator.)
3a. On yokes with a rib, attach the positioner’s
mounting bracket (12) in accordance with the
dimensions of Figure 4 to the actuator
yoke. Use the center hole of the mounting
bracket (12) for attachment using the rib
mounting bracket (12) will give the proper
dimensions. (Figure 4 is shown as right-hand;
if left-hand is required, then dimensions are
mirror-imaged.)
3b. On yokes without a rib, attach the positioner’s
mounting bracket (12) in accordance with the
dimensions of Figure 4 to the actuator yoke.
Use two yoke mounting screws and nuts
(10B) and the two holes closest to the frontal
position when properly rotated. (Figure 4 is
shown as right-hand; if left-hand is required,
then dimensions are mirror imaged.)
IOM-9540L2
TABLE 1
CONTROL VALVE POSITIONER PLUG ACTION
CASHCO ACTION/FAIL MOUNTING ACTION CHANGEOVER STEM TRAVEL WITH SIGNAL
PRODUCT POSITION LOCATION PLATE SETTING DIRECTION INCREASING
2"- 2266 to Open
ATO-FC Right Direct Downwards Opens
N
U
& 964
(Non- ATC-FO Left Direct Downwards Closes
Reversible to Close
Actuator,
Reversible ATC-FO Right Reverse Downwards Opens
Trim) to Close
ATO-FC Left Reverse Downwards Closes
987, 988, ATO-FC Left Direct Upwards Opens
988MB, 989, to Open
N
U
N
U
N
U
N
U
to Open
520, 521,
SCV-S, ATC-FO Right Direct Upwards Closes
SCV-30 to Open
(Non-
Reversible ATC-FO Left Reverse Upwards Opens
Trim, to Open
N
U
N
U
Reversible
OR Non- ATO-FC Right Reverse Upwards Closes
Reversible to Open
N
U
Actuator)
12
10B
10A
or
CROSS-SECTION
Figure 3A
CROSS-SECTION
SIDE VIEW
2-1/8"
21
17
2-7/8"
13
11
BP
Figure 4
IOM-9540L
SIDE VIEW
Figure 3B
Figure 5A (Model 987)
3
Figure 5B: (Model 964 w/left and right mounting positions)
4. If the control valve does not have an accessory
plate (AP) installed, the actuator stem must be decoupled from the valve stem. (Refer to the valve/
actuator instructions for de-coupling procedure.)
Place accessory plate (AP) as indicated in Figures 5A, 5B or 5C.
5. If it is necessary to re-orient an existing accessory
plate (AP) that is secured to the valve’s stem by a
jam nut, loosen the jam nut so that the accessory
plate (AP) is loosened enough that it can be tipped
and rotated to the proper frontal position. Retighten the accessory plate (AP) jam nut. Attach
the stem feedback carrier bolt (14) to the accessory plate (AP) using the Tinnerman nut.
(Note: Above is true for the 987 and 2296 actuators.
For Models 30, 55D, 55R, 115D and 115R actuators,
separate accessory plates are required for “left” or
“right” mounting positions.)
Figure 5C: (Model 521 w/Model 30 actuator)
Figure
6A
6. Remove the positioner cover (WC). Orient the unit
so that the DAMPING & GAIN labels are top/
center, and the gauges (1A & 1B) are right side up.
7. Fasten the positioner baseplate (BP) to the mounting bracket (12) using the two mounting screws
(11) (See Figure 4).
8. With the actuator at zero stroke (“LOAD” = 0 psig;
i.e. no air to actuator diaphragm), attach the
feedback lever (13) on the main shaft (17) (Figure
4) of the positioner with the feedback carrier bolt
(14) located in the feedback lever’s (13) slot. The
compensating spring (18) must be located above
the feedback carrier bolt (14) when the unit mounting is on the right (See Figure 6A), and below the
feedback carrier bolt (14) when the mounting is on
the left. (See Figure 6B). Hand tighten socket cap
screw (21) (Figure 4); DO NOT WRENCH
TIGHTEN!
Figure 6B
9. Press the stroke factor lever (19) (See Figure 7) of
the positioner’s internals against the travel stop
pin (20) and hold firmly in place. Place the #5 Allen
wrench into the head of the socket cap screw (21),
and tighten while still holding stroke factor lever
(19). Tighten firmly. (A 5 mm, #5 metric Allen
wrench should be provided with the unit.)
10. Install tubing fittings with acceptable thread sealant and tubing from the unit’s 1/4” NPT (female)
“OUTPUT 1” port of the adapter block(AB) up to
IOM-9540L4
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