Type 95Hd Differential Pressure Reducing Regulator; For Types Mr95Ld And Mr95Hd Differential Pressure Regulators - Fisher MR95L Instruction Manual

HANDWHEEL
October 2006

Type 95HD Differential Pressure Reducing Regulator

CONTROL SPRING
DIAPHRAGM
PITOT TUBE
STEM
ORIFICE
VALVE PLUG
FRONT AND INTERNAL VIEW OF
TYPE MR95HD WITH INTERNAL PRESSURE REGISTRATION
INLET PRESSURE
OUTLET PRESSURE
LOADING PRESSURE
*PRESSURE A MAY BE SUPPLIED BY ANOTHER PRESSURE SYSTEM OR A MANUAL LOADING REGULATOR.
For Types MR95LD and MR95HD
Differential Pressure Regulators
Types MR95LD and MR95HD regulators maintain
a differential pressure between the loading supply
pressure and the downstream pressure of the regulator.
See Figure 2. The design of the regulator isolates the
diaphragm and pressure response chamber from the
main flow stream. The downstream pressure (outlet
pressure) is registered under the diaphragm through
the pitot tube or registration hole. If the downstream
pressure increases, pressure under the diaphragm
PRESSURE A*
(SPRING CASE
LOADING
PRESSURE)
PRESSURE A*
SPRING SETTING =
PRESSURE B
PRESSURE B
(OUTLET
PRESSURE)
Figure 2. MR95 Series Operational Schematics (continued)
BACK VIEW OF
TYPE MR95HD WITH EXTERNAL PRESSURE REGISTRATION
also increases. This force overcomes the spring
compression and loading supply pressure, allowing
the stem to rise. The valve plug spring forces the valve
plug closer to the orifice. Flow through the regulator
is reduced so that downstream pressure returns to
the desired differential level. When the downstream
pressure decreases, the opposite action takes place.
Pressure under the diaphragm decreases. The valve
stem pushes the valve plug downward, opening the
flow stream and increasing the fluid flow through the
regulator. Downstream pressure rises back to the
desired differential level.
MR95 Series
Type 95HD
CONTROL LINE TAP
5