Grain Systems PNEG-1459 - Manual (Page 46)

46 PNEG-1459 L Series Operators
PROPANE VAPORIZER SEASONAL INSPECTION
LQUID PROPANE MODELS ONLY - Liquid propane fueled dryers are equipped with a vaporizer that operates at relatively
high pressure. Since leakage can result in release of liquid propane, it is extremely important to maintain the condition of all
components to provide safe operation. Vaporizers should be inspected and serviced prior to each season of operation, includ-
ing the following:
1. Carefully inspect the surfaces of the vaporizer coil and the liquid inlet and vapor outlet pipes for evidence of severe cor-
rosion or abrasion of metal which could cause subsequent leakage of liquid propane, gross overheating, and fire hazard.
Insecure mounting of either the vaporizer or its plumbing due to loosened bolts can cause erosion of the pipe metal at the
point of maintained contact. If there has been significant abrasion of the steel vaporizer pipe, it must be replaced.
2. Inspect the fuel train components: Liquid solenoid valve, pressure relief valves, pressure regulator, Vapor Hi-limit Ther-
mostat, and the fuel lines and fittings.
MAIN CONTROLS
1. SCR speed control: The metering roll speed pots on the front of the control box regulate the speed of the DC motor
which drives the metering rolls. The scale of adjustment is from 0 to 999 which represents the flow of grain past the metering
rolls as a percent of the maximum grain discharge rate for the dryer.
Note: When the control is set to the maximum discharge rate (999), the metering roll speed should be 17.5 RPM for 8"
discharge auger.
2. DC electric motor: The direct current (DC) motor provides the drive for the metering roll, and is located on the front
left hand side of standard model dryers. The output shaft of the motor is connected directly to the gear box assembly. The
DC motor requires no operational adjustment as it is completely controlled from the control box.
3. Speed reducer gear box: The direct drive gear box provides the required speed reduction, and transmits power to the
metering rolls through a drive chain arrangement. The gear box does not require adjustment. The drive chain should also be
periodically lubricated and tightened as necessary.
4. Unload auger time delay: The delay controls the bottom auger system and causes the unload auger (and any connected
auxiliary unloading conveyors) to continue operating for a programmed amount of time, even after the metering rolls stop.
This feature permits the clean out of grain within the unloading equipment at the end of all discharge cycles.
5. If a foreign object becomes lodged in the metering rolls and jams the system, the unloading auger will stay in motion.
However, the metering roll drive will stop and the DC motor should stall out. The Vision Control System will shut down the
dryer after a two minute period.
To determine if the metering problem is from blockage, perform the following test with the power off. Remove the drive
chain by loosening the motor mounting bolts. Refer to photo, and place a pipe wrench on the hub of the roller chain sprocket,
on the left hand metering roll at the drive end of the dryer. Apply up to 100 ft.lbs. of force, and attempt to rotate the roll to-
ward the inside of the dryer. If the metering roll will turn, then repeat for right hand side. If the metering roll will turn, it can
be assumed that no blockage exists, and the problem is from some other cause. Check for a break in the power train, chain,
drive key, pin, etc.
CAUTION : Keep hands away from sprocket teeth to avoid injury from chain backlash, as a result of torsion build up
in the system caused by the jam.
HOW TO CLEAR A JAMMED METERING ROLL
Place a pipe wrench on the hub of the sprocket of the jammed metering roll and turn the roll. First, backward, and then, for-
ward several times in an attempt to dislodge the object, and clear it through the roll. If this is not successful, have an assistant
turn the metering roll, and attempt to locate the jam by sound. Shut down the fan/heater, and eliminate any other noise when
making this check. Once the location is determined, the roll can be reached from the outside by opening the access door to re-
move the foreign object causing the jam (before opening doors see below). The service tool must be inserted before opening
doors. First, swing open the plenum bottom closure panel. Insert the service tool above the metering roll.
SERVICE