Data Sheet

Bulletin 71.2:LR125
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Powder Paint Coating—Carbon steel body is powder
paint coated providing superior impact, abrasion and
corrosion resistance.
Pilot Type Description
Type MR95H—High-pressure pressure reducing pilot
for 15 to 150 psig / 1.0 to 10.3 bar outlet pressures.
Designed to handle inlet pressures up to 300 psig /
20.7 bar.
Principle of Operation
As long as the outlet (control) pressure is above the
outlet pressure setting, the pilot valve plug or disk
remains closed (Figure 3). Force from the main spring, in
addition to inlet pressure bleeding through the restrictor,
provide downward loading pressure to keep the main
valve diaphragm and plug assembly tightly shutoff.
When the outlet pressure decreases below the pilot
outlet pressure setting, the pilot plug or disk assembly
opens. Loading pressure bleeds downstream through
the pilot faster than it can be replaced through the
supply line. This reduces loading pressure on top of
the main valve diaphragm and plug assembly and
lets the unbalanced force between inlet and loading
pressure overcome the main spring force to open the
Type LR125 diaphragm and plug assembly.
As the outlet pressure rises toward the outlet pressure
setting, it compresses the pilot diaphragm against
the pilot control spring and lets the pilot valve plug
or disk close. Loading pressure begins to build up
on the Type LR125 diaphragm and plug assembly.
The loading pressure, along with force from the main
spring, pushes the diaphragm and plug assembly onto
the tapered-edge seat, producing tight shutoff.
Figure 3. Type LR125 Operational Schematic
INLET PRESSURE
LOADING PRESSURE
ATMOSPHERIC PRESSURE
OUTLET PRESSURE
M1215
TYPE LR125 WITH TYPE MR95H PILOT AND TYPE 112 RESTRICTOR
CONTROL SPRING
TYPE 112 RESTRICTOR
SUPPLY LINE
TYPE MR95H PILOT
DIAPHRAGM
VALVE PLUG
MAIN SPRING
DIAPHRAGM AND
PLUG ASSEMBLY
INTERNAL STRAINER
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