GAUGE BOARD SHUTOFF CONTROLS

The gauge board has a switch mounted externally near the bottom of the gauge board for a preset “full” level (Fig. 11). When the tank is being filled, the red target (“bulls eye”) travels down the gauge board and actuates the switch. Consequently, it causes the unloading pump to shut off.

Figure 10. Switch at top of gauge board is for preset "empty" level.

Figure 11. Switch at bottom of gauge board is for preset "full" level.

The gauge board also has a switch mounted externally near the top of the gauge board for a preset “empty” level (Fig. 10). When asphalt is being used, the “bulls eye” travels up the gauge board and actuates the switch. When the switch is actuated it causes the power-actuated valve to rotate so as to bypass the hot oil, thereby shutting off heat to the tank. This is done to prevent coking the coils.

Asphalt residues can build up on the cable that supports the bulls eye, causing the cable to stick so the bulls eye cannot travel freely. Thus, the bulls eye may not engage the switches that shut off the unloading pump tank or the hot oil. The remedy is to manually pull out as much of the cable as you can and clean the asphalt from it.

It is helpful to use two people to check both gauge board shut off functions. Tie a rope about 50 feet long to the bulls eye so you can pull it down while standing on the ground.

When checking for proper high level control, one person should be at the unloading pump controls (Fig. 15). The other person should be on the ground holding the rope that is tied to the bulls eye of the gauge board. Make sure the pump controls are set for the tank you are testing. Also make sure that the tank fill valve is open. Momentarily turn the unloading pump on. It should operate. Pull the bulls eye down until it actuates the high level switch at the bottom of the gauge board (Fig. 11). Turn the unloading pump on again. The pump should not operate. Moreover, this should set off an alarm horn and cause a red light to come on at the controls of the unloading pump.

When checking for proper low level control, one person should be at the power-actuated hot oil valve controls (Fig. 3 and 4). Reset the UL temperature controller to a set point higher than the current temperature of the asphalt and make sure the power-operated hot oil valve is diverting hot oil so as to heat the tank coils.

The other person should be on top of the tank and should manually actuate the low level switch at the top of the gauge board (Fig. 10). The power-actuated valve should rotate so as to bypass the hot oil, thereby shutting off heat to the tank.

Reset all controls to their normal condition.