Burner Control Valve - Aerotech BT 400-46 Installation And Operation Maintenance

Section 4
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4.15

Burner Control Valve

4.16 The burner control valve (see figure 4-3) is not intended for manual heat regulation, the manual
control knob serving only to either full close (burner on) or fully open (burner off) the primary by-pass
line which returns fuel back to the tank. Pressing the knob downward seats a ball which seals the inner
axial passage leading to the fuel outlet. At the same time, fuel under pump pressure flows into the area
over the diaphragm, forcing the diaphragm downward against the loading spring. This allows the push
pins to drop so that the pressure balancing spring may force the movable sleeve downward to hold the ball
firmly in its seat, closing the outlet passage. Thus the fuel pressure acts to keep the valve closed. Lifting
the knob raises the movable sleeve, permitting the lower plunger to be in turn raised by the plunger spring,
freeing the ball from its seat. Fuel then flows through the inner valve body to the outlet. This relieves the
fuel pressure on the diaphragm and the valve returns to the open position.
4.17 The burner control valve also serves as an overheat protection safety valve. This is achieved through the
action of a sensing element in the discharge air system. When the discharge air temperature exceeds safe
limits (about 350°F), the thermostatic medium in the sensing element will expend sufficient pressure to
assist the loading spring so that together they force the diaphragm upward, opening the valve. This turns
off the burner. The valve will not close again to permit subsequent burner operation until operated
manually.
AEROTECH HERMAN NELSON INTERNATIONAL INC.
100 Eagle Drive, Winnipeg, Manitoba Canada R2R 1V5
Phone: 204-633-1999 (24 Hours) Fax: 204-694-1612 Email:
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