Data Sheet

Bulletin 71.1:MR105
4
Table 3. Maximum Inlet, Outlet and Emergency Casing Pressures
(1)
BODY
MATERIAL
END
CONNECTION
MAXIMUM INLET PRESSURE MAXIMUM OUTLET PRESSURE MAXIMUM EMERGENCY CASING
psig bar
Low-Pressure
Actuator
High-Pressure
Actuator
(2)
Low-Pressure
Actuator
High-Pressure
Actuator
(2)
psig bar psig bar psig bar psig bar
Cast Iron
NPT 340 23.4
70 4.8
340 23.4
70 4.8
340 23.4
CL125 FF 175 12.1 175 12.1 175 12.1
CL250 RF 400 27.6 400 27.6 400 27.6
WCC steel
NPT 400 27.6
70 4.8
400 27.6
70 4.8
400 27.6
CL150 RF 245 16.9 245 16.9 245 16.9
CL300 RF
400 27.6 400 27.6 400 27.6
CL600 RF
PN 16 RF 245 16.9 245 16.9 245 16.9
PN 16/25/40 RF 400 27.6 400 27.6 400 27.6
CF8M
Stainless steel
NPT 400 27.6
70 4.8
400 27.6
70 4.8
400 27.6
CL150 RF 225 15.5 225 15.5 225 15.5
CL300 RF
400 27.6 400 27.6 400 27.6
CL600 RF
PN 16 RF 225 15.5 225 15.5 225 15.5
PN 16/25/40 RF 400 27.6 400 27.6 400 27.6
CF3M
Stainless steel
NPT 400 27.6
70 4.8
400 27.6
70 4.8
400 27.6
CL150 RF 185 12.7 185 12.7 185 12.7
CL300 RF
400 27.6 400 27.6 400 27.6
CL600 RF
PN 16 RF 185 12.7 185 12.7 185 12.7
PN 16/25/40 RF 400 27.6 400 27.6 400 27.6
1. Based on a maximum temperature of 250°F / 121°C.
2. Maximum outlet and emergency casing pressures for constructions with Fluorocarbon (FKM) diaphragm are limited to 230 psig / 15.8 bar or the body rating limit, whichever is lower.
ANSI/FCI 70-3-2004 Class VI Shutoff—Soft-seat
valve plug disks for tight shutoff.
Multiple End Connection Options—Type MR105 is
available in several end connection congurations to
meet demands on application requirements.
P
1
= P
2
on High-Pressure Actuator—Inlet pressure
rating equals outlet pressure rating on high-pressure
actuator constructions up to 400 psig / 27.6 bar.
Easy Drain—Feature allows you to drain the system
without expensive spool pieces saving you time
and space.
Easy Bleed—Feature allows you to purge the air
trapped underneath the diaphragm when the high-
pressure regulator is installed in the upright position,
which improves speed of response.
Principle of Operation
Refer to Figure 2. The Type MR105 is a direct-
operated pressure reducing regulator. Downstream
pressure is registered externally through a 1/2 NPT
control line tapped in the low-pressure actuator bonnet
or in the high-pressure actuator lower casing. When
downstream demand decreases, the pressure under
the actuator diaphragm increases. This pressure
overcomes the regulator setting (which is set by
the regulator control spring). Through the action of
the actuator stem and valve spring, the valve plug
moves closer to the seat ring and reduces ow. When
demand downstream increases, pressure under the
actuator diaphragm decreases. Spring force pushes
the actuator stem downward, the valve plug moves
away from the seat ring and the ow increases
downstream as the regulator opens in response to
the decreased pressure underneath the diaphragm.
The downward motion of the plug allows gas to ow
through the cage into the downstream system.
Increased downstream pressure permits the regulator
to close. The combination of valve spring force and
valve plug unbalance provides positive valve plug
shutoff against the port and upper seals.
Overpressure Protection
Type MR105 regulator with the low-pressure actuator
has outlet pressure ratings lower than the inlet
pressure ratings. Complete downstream overpressure
protection is needed if the actual inlet pressure
exceeds the outlet pressure rating.
Overpressuring any portion of a regulator or
associated equipment may cause personal injury,
leakage or property damage due to bursting
of pressure-containing parts or explosion of
accumulated gas. Provide appropriate pressure-
relieving or pressure-limiting devices to ensure