overpressure Protection
Maximum inlet pressures depend upon body
materials and temperatures. Refer to the nameplate
for the maximum inlet pressure of the valve. The
valve should be inspected for damage after any
overpressure condition.
fisher™ backpressure
regulators are not asME safety relief valves.
startup
The backpressure regulator is factory set at
approximately the midpoint of the spring range or
the pressure requested, so an initial adjustment
may be required to give the desired results. With
proper installation completed and relief valves
properly adjusted, slowly open the upstream and
downstream shutoff valves.
adjustment
To change the control pressure, remove the closing
cap or loosen the locknut and turn the adjusting
screw clockwise to increase control pressure or
counterclockwise to decrease pressure. Monitor
the control pressure with a test gauge during the
adjustment. Replace the closing cap or tighten the
locknut to maintain the desired setting.
taking out of service (shutdown)
!
WarNINg
to avoid personal injury resulting from
sudden release of pressure, isolate the
backpressure regulator from all pressure
before attempting disassembly.
Parts list
Key Description
1
Control Spring
2
Adjusting Screw
3
Closing Cap
4
Lower Control Spring Seat
5* Diaphragm
6
Lower Diaphragm Plate
7
Diaphragm Plate Gasket
8
Pusher Post
9
Lever Assembly
11 Machine Screw
13 Stem
14* Cotter Pin
16* Body Gasket
17 Split Ring
19 Union Nut
20 Lower Casing
21 Diaphragm Case Cap Screw
22 Hex Nut
23 Spring Case
24 Diaphragm Plate
25* Disk Assembly
27 Orifice
28 Body
29 Pipe Plug
30 Diaphragm Cap Screw
35* Closing Cap Gasket
38 Body Cap Assembly
40 Disk Shut-Off Stem
41 Disk Spring
44 Upper Spring Seat
46 Valve Disk Washer
47 Disk Screw
50 Nameplate
51 Drive Screws
75 Bushing
78 Pipe Plug
Table 1.
Body Sizes and End Connection Styles
BoDy sIzE
BoDy MatErIal
DN
In.
Cast Iron
steel
stainless steel
Hastelloy
®
C
40 and 50
1-1/2 and 2
NPT
NPT, SWE, CL150 RF,
CL300 RF, PN 16/25/40
NPT, SWE, CL150 RF,
CL300 RF, PN 16/25/40
CL150 RF
Table 2.
Control Pressure Ranges
CoNtrol PrEssurE raNgE
sPrINg Color
mbar
In. w.c.
5 to 12
(1)(2)
12 to 37
(1)(2)
20 to 69
2 to 5
(1)(2)
5 to 15
(1)(2)
8 in. w.c. to 1 psig
Red
Gray
Dark Green
69 mbar to 0.19 bar
0.14 to 0.24 bar
0.28 to 0.48 bar
1 to 2.8 psig
2 to 3.5 psig
4 to 7 psig
Orange
Green stripe
Red
1. Spring ranges based on spring case installed pointed down. When installed pointed up, spring range increases 5 mbar / 2 in. w.c.
2. Do not use Fluorocarbon (FKM) diaphragm with these springs at diaphragm temperatures lower than 16°C / 60°F.
*Recommended spare part
Type Y696
2
