B&C Technologies DI-325 Industrial - Manual (Page 25)

COMPONENT SYSTEM DESCRIPTIONS
4-2
1. Load Door Switches
There are two (2) of these switches located under the main loading doors. These switches
ensure that the doors are closed before the dryer can start. If the dryer is started when the load doors
are open, the microprocessor controller (computer) LED display will show “door”
2. Lint Basket Switch
This switch ensures that the lint basket is closed be before the dryer can start. This switch is
located at the front of the dryer at the right side of lint basket. If the lint basket is open when the
dryer is started, then the microprocessor controller (computer) LED display will show “door”
3. Basket (tumbler) Hi – limit Safety Thermostat
This disc temperature switch has a setting of 225 ºF. It is located below the basket (tumbler)
on the temperature sensor bracket, along side the computer sensor, and is an automatic reset type of
switch. Access to this switch is gained by sliding / pulling the lint basket / drawer completely out of
the dryer.
This switch backs up the computer sensor and in case of a computer sensor malfunction will
prevent the basket’s (tumbler’s) temperature from becoming excessive. If these switch trips, the gas
flow to the burner box will be shut down. However the basket (tumbler) will still rotate
4. Burner Box Hi – limit Safety Thermostat (GAS DRYERS ONLY)
This disc temperature switch has a setting of 330 ºF. It is located on the right side of the
burner box, and is an automatic reset type of switch. This switch ensures that there is proper airflow
through the burner box. Upon a low airflow condition, which ensures may be caused by a clogged
lint screen, excessively long or blocked exhaust duct, or improper make – up air, the temperature in
the burner box will increase tripping this switch. This will shut off the gas flow to the burner box.
However the basket (tumbler) will still run.
5. Sail Switch (GAS DRYERS ONLY)
The sail switch is located in the front top of the burner box. A sail switch consists of a round
damper plate on a lever arm which is in contact with an electric switch. When the air blower comes
on, it draws air through the gas burner. This creates a negative pressure inside the burner box, and
this negative pressure pulls in the round damper and activates the sail switch. If there is an improper
(low) airflow through the dryer, the sail switch damper will not pull in, preventing the heat from
Low airflow through the dryer will be caused by overly long or blocked exhaust ducting,
lack of make – up air, or a clogged lint screen.
This system consists of a hinged damper plate, pneumatic piston, and 24 volt solenoid valve
with a needle valve to control the speed of the piston actuation.
On a call for heat, a 24 volt signal is applied to the 3 ways / 2 position solenoid valves. This
signal switches the valve so that compressed air is sent to the piston. The piston rod extends,
pushing the hinged steam damper plate to the open position. This allows room air to be drawn
through the hot steam coil and then through the basket (tumbler).
When the temperature set point has been reached, the 24 volt signal is removed from the
solenoid valve, so that the solenoid valve blocks the air supply to the piston and the air in the piston
is bled to the atmosphere. The spring in the piston now retracts the piston rod, closing the steam
D. SAFETY DEVICES
E. STEAM DAMPER ACTUATOR SYSTEM