Cleaver-Brooks CBH 40 - Page 16

Chapter 1-General Description and Principles of Operation
GAS PILOT VALVE (Figure 1-4)
A
solenoid valve that opens during the ignition
period to admit fuel to the pilot. It closes after
main flame is established. The sequence of energiz-
ing and de-energizing is controlled by the program-
ming relay.
GAS PILOT SHUT-OFF COCK (not shown)
For manually opening or closing the gas supply to
gas pilot valve.
GAS PRESSURE GAUGE (not shown)
Indicates gas pressure to pilot. (Optional)
GAS PRESSURE REGULATING VALVE
(Figure 1-4)
Reduces incoming gas pressure to suit the pilot's
requirement of between 5" to 10" W.C.
BUTTERFLY GAS VALVE (Figure 1-l)
The pivoted disc in this valve is actuated by con-
necting linkage from the damper motor to regulate
the rate of gas flow to the burner.
MAIN GAS VALVE (Figure 1-4)
An
electrically actuated shutoff valve. When open,
it admits main flame gas through the butterfly gas
valve. The valve may be equipped with a "proof of
closure" switch connected into a pre-ignition inter-
lock circuit. A second motorized shutoff gas valve
is often used.
GAS VENT VALVE: (Figure 1-4)
(Optional)
A normally open solenoid valve installed between
the two main gas valves to vent gas to the at-
mosphere should any be present in the main gas
FIGURE 1-6. FUEL OIL CONTROL VALVES
1-8