American Dryer Corp. AD-400 - Manual (Page 37)

To open the loading door, a 115-volt signal is applied to SI, the coil of the valve that supplies air to the
door piston's bottom port. The valve will open, and 80 psi of air is supplied to the bottom port of the
door piston. The piston rod will extend, and the door will open. No voltage is applied to S2, the coil of
the valve that controls the air supply to the door piston top port so that this line is bled to atmosphere.
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To close the loading door, the voltage signals are reversed, and the loading door will close.
The solenoid coils on the 7-station manifold have a pilot light that illuminates when coil power is
applied. This feature will ease servicing.
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NOTE: If there is a power loss to the dryer, all cartridge valves will bleed to atmosphere so
loading doors can be opened or closed by hand.
Connected to each of these cartridge valves is an adjustable flow control valve, to adjust the speed at
which the doors open or the heat reclaimer damper operates.
5. Sprinkler Valves
The sprinkler is controlled by an air-operated on/off water control valve. This valve is actuated by a
3-way/3-port/2-position double solenoid pneumatic valve, located on the pneumatic control panel. This
solenoid is the double solenoid type so that if power to the sprinkler is cut off after the sprinkler activates,
then the 3-way solenoid valve will lock in position, keeping the sprinkler on.
E. GAS BimNER AND IGNITION SYSTEM
The ADG-400 dryer gas burner system operates on a hi-fire/lo-fire gas rate sequence to accurately control
the tumbler's drying temperature. Hi-fire is set at 1.6 mil. Btuh, and lo-fire is set at 40,000 Btuh. The
burner always ignites in the lo-fire mode before cycling to hi-fire.
Upon a call for heat, the dryer computer sends a 120-volt signal to the burner controller module (BCM)
which initiates and controls the ignition sequence. The BCM insures that all the dryer safety switches are
closed before turning on the combustion air burner fan, then checks to insure that the burner fan air
switch has closed. Tlie pilot gas line solenoid valve is then opened, and a spark is generated by the spark
plug, igniting the pilot flame. Once the pilot flame is established, the flame rod, which sits in this pilot
flame, heats up and signals the BCM. The main motorized gas valves op>en in sequence, and the hi/lo
electric butterfly valve modulates from lo-fire to hi-fire.
The burner controller module (BCM) has five (5) LED's on its cover for ease of troubleshooting, as well as
dip switches inside for ease of programming.
The burner controller module controls all of the gas burner ignition components except for the hi/lo
electric butterfly valve actuator. When the drying set point temperature is reached, the dryer computer
cycles this actuator to lo-fire.
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