Types 66R and 66RR
3
M1041
!
3.
Install a Type 66R or 66RR relief valve in a horizontal
pipeline with the diaphragm casings above the body.
Other orientations will change the relief set pressure
and set pressure range due to the weight of the internal
parts. The flow through the relief valve must comply with
the flow arrow on the body.
4. An upstream control line is not required for a standard
Type 66R relief valve with internal registration through
a stem guide (key 41, Figure 6). However, for an
optional Type 66R relief valve with sealing diaphragm
(key 14, Figure 6), connect a control line to the 3/4 NPT
tapped connection boss on the diaphragm case (key 3,
Figure 6) as shown in Figure 3.
5. For a Type 66RR relief valve used in a relief application,
connect an upstream control line to the 1/2 NPT
connection on the pilot diaphragm case (key 4, Figure 8).
For other typical applications, piping arrangements are
shown in Figures 4 and 5. Regardless of Type 66RR
installation, the pipe plug (key 78, not shown) will have
to be removed from the vent of the Type T208RR pilot
spring case (key 3, Figure 8).
6. On backpressure or bypass applications, install a three-
valve isolating bypass, and vent valves immediately
upstream and downstream of the unit, if system
operation is necessary during maintenance.
Relief valves vent gas from the main valve
outlet and from the exhaust of the pilot if
used. In hazardous gas service, personal
injury and equipment damage may occur
due to fire or explosion of vented gas that
has accumulated. To prevent such injury and
damage, provide piping or tubing to vent
the gas to a safe location. Protect the vent
opening against anything that could clog it.
7. The standard Type 66R spring case (key 2, Figure 6)
has a Type Y602-10 vent assembly (key 30, Figure 6)
installed in the 3/4 NPT spring case tapping. The vent
may be removed and obstruction-free piping or tubing
installed for remote piping of the spring case or for
pressure loading of the spring case as shown in Figure 5.
If kept in the spring case, the vent must be protected
against clogging.
PILOT
CONTROL
SPRING
DIAPHRAGM
VALVE
PLUG SKIRT
FIXED
RESTRICTION
PILOT
VALVE DISK
MAIN VALVE
DIAPHRAGM
TYPE T208RR
PILOT
VALVE STEM
VALVE PLUG
SKIRT
MAIN VALVE
TYPE 66RR
TYPE 66R
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
LOADING PRESSURE
Figure 2
. Operational Schematics
Table 1
. Type T208RR Pilot Control Spring Selection
MAIN VALVE
CONSTRUCTION
RELIEF SET PRESSURE RANGE
PILOT CONTROL SPRING
Part Number
Color Code
Wire Diameter,
In. / mm
Free Length,
In. / mm
Standard
4 to 9 in. w.c. / 10 to 22 mbar
(1)
5 to 15 in. w.c. / 12 to 37 mbar
(1)
12 to 28 in. w.c. / 30 to 70 mbar
(1)
0.9 to 2.5 psig / 0.06 to 0.17 bar
1.3 to 4.5 psig / 0.09 to 0.31 bar
1B653827052
1B653927022
1B537027052
1B537127022
1B537227022
Red
Olive drab
Yellow
Light green
Light blue
0.085 / 2.16
0.105 / 2.67
0.114 / 2.90
0.156 / 3.96
0.187 / 4.75
3.625 / 92.1
3.750 / 95.3
4.188 / 106
4.060 / 103
3.938 / 100
Special
3.8 to 7 psig / 0.26 to 0.48 bar
1B537327052
Black
0.218 / 5.54
3.980 / 101
1. Published ranges are with the spring case pointed up.
WARNING
