Data Sheet

Bulletin 71.2:92C
6

Refer to the schematic in Figure 3. With a pressure-
loaded regulator, a remote, adjustable loading regulator
provides loading pressure to the top of the main valve
diaphragm. Downstream pressure registers under the
main valve diaphragm through the pilot tube.
When downstream pressure decreases, it registers
under the diaphragm and allows the stem and plug to
move downward, thereby opening the valve to increase
downstream pressure.
When downstream pressure increases, it registers
under the diaphragm and forces the stem and plug
to move upward. The upward force of the spring
causes the valve to close, which decreases ow to
the downstream system thus decreasing downstream
pressure. In hot air service, supply air above the
diaphragm becomes compressed and is vented to the
atmosphere. If a steam supply is used, the steam is
vented downstream.

Refer to the schematic in Figure 4. Once placed in
operation, the upstream Type 6392 pilot senses the
intermediate pressure between both valves, and the
Type 6492HM or 6492HTM pilot senses downstream
pressure of the second valve. As demand for ow
increases, intermediate pressure will fall causing the
Type 6392 pilot to open. As the Type 6392 pilot valve
opens, loading pressure to the main valve increases,
opening the main valve.
The Type 6492HM or 6492HTM safety override
pilot remains open because its setpoint is above the
setpoint of the downstream valve. In the unlikely event
that the downstream valve fails open, downstream
pressure will rise above the downstream valve’s
setpoint. This pressure is sensed by the
Type 6492HM or 6492HTM safety override pilot. As
downstream pressure increases the safety override
pilot closes, reducing loading pressure to the main





EO557
Figure 4. Type 92C with Type 6492HM Safety Override Pilot Operational Schematic






Table 4. Type 6492 Safety Override Pilot Spring Ranges and Minimum Differential Pressures
 ) 

)
6492HM
10 to 30 (0,69 to 2,1) Yellow 5 (0,34) over normal distribution pressure
25 to 75 (1,7 to 5,2) Green
10 (0,69) over normal distribution pressure
70 to 150 (4,8 to 10,3) Red
6492HTM
80 to 250 (5,5 to 17,2)
Unpainted - - - -
15 to 100 (1,0 to 6,9)