Data Sheet

Bulletin 71.1:133
4
Introduction
Description
The 133 Series direct-operated gas regulators, shown
in Figure 1 are primarily designed for industrial and
commercial applications supplying gas to furnaces,
burners, and other appliances. The 133 Series
balancing system enables the regulator to provide
accurate control of gas pressure for maximum
combustionefciencydespitevaryinginletpressure
conditions. The single port construction provides
bubble-tight shutoff. An external downstream control
line is required for the operation of the regulator. Refer
to Table 1 for outlet pressure ranges of each type.
133 Series regulators are available in a 2 inch / DN 50
bodysizewitheitherNPTorangedendconnections.
An optional restriction collar (Figure 2) can be installed
if wide-open capacity is too high for applications using
a relief valve as overpressure protection. The collar
reduces wide-open capacity to 25%, 40%, or 60% of
standard wide-open capacity.
Principle of Operation
Refer to the operational schematics in Figure 4. 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 rangeability and performance.
Two-Way Stabilizer Vent Valve on
Types 133H, 133L, and 133Z
When the regulator responds to an increase in
downstream pressure, the diaphragm moves upward.
As the diaphragm rises, movement of air forces the
lower vent stabilizer upward, carrying the upper
stabilizer with it (see Figure 5). This allows the air
above the diaphragm to vent to atmosphere rapidly
enough to minimize lag in diaphragm movement.
Asthediaphragmfalls,airrushesintheventtoll
the partial vacuum created, forcing the upper vent
W6883/IL
Figure 3. Type 133HP Regulator