Emerson Fisher 133H - Principle Operation

133 Series
3
Figure 2. Operational Schematic of Type 133L Regulator (Also Typical of Type 133H)
A6555
Principle Operation
Refer to the operational schematics in Figures 2 and 3.
In the 133 Series, downstream pressure is registered
under the diaphragm via the external control line and
is used as the operating medium. Increased demand
lowers the downstream pressure and allows the spring
to move the diaphragm and stem assembly down,
opening the valve disk and supplying more gas to the
downstream system. Decreased demand increases
the downstream pressure and moves the diaphragm
and stem assembly up, closing the valve disk and
decreasing the gas supply to the downstream system.
Boosting System
The 133 Series incorporates a balancing diaphragm
and a boosting system. When the regulator is locked
up, inlet pressure is registered on the top of the valve
disk and on the bottom of the balancing diaphragm
through registration holes in the top of the cage. Also,
downstream pressure is registered on the bottom
of the valve disk and on the top of the balancing
diaphragm through a passage formed by grooves in
the registration disk and an annular space between the
stem and stem sleeve.
When the valve disk is open, gas ows from the inlet
over the edge of the valve disk to the outlet. Under
the valve disk near the registration disk, there is little
gas ow. The gas pressure near the registration disk
is higher than it is in the ow path where gas velocity
tends to lower the pressure. The higher pressure
near the disk is registered on the top of the balancing
diaphragm through the registration disk and the
annular space between the stem and stem sleeve.
This pressure registered on the top of the balancing
diaphragm aids downward disk travel and
compensates for spring and diaphragm effect. This
improves regulator range ability and performance.
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
BOOST PRESSURE
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
BOOST PRESSURE
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
BOOST PRESSURE