Grizzly G8297, G8299, G8298 instruction manual Operations, General, Pressure safety relief valve

SECTION 4: OPERATIONS

General

The pump produces compressed air which goes into the air tanks through the delivery pipe and the check valve. When the air pressure arrives at the factory pre-set level of 135 PSI, the pressure switch shuts off the electrical current to the axial electric pump. At the time it shuts off, it dis- charges the air held in the pump cylinder to the delivery pipe. This allows the pump to be depres- surized so it can easily restart. When the pres- sure in the air tanks falls below the minimum fac- tory set pressure of 105 PSI, the pump cycles again to build the pressure back up. The pressure switch is supplied with a discharge valve with delayed closing, which reduces the strain on the pump and the motor during startup.

The compressor is operating correctly when there is a bleed of air every time the motor is switched off. You will notice an audible air discharge each time the pump motor stops. On these compres- sors, the pump will cycle first to minimize the amperage draw and will bleed off air through the cold-start valve. The valve will stay open until approximately 20 PSI is reached in the air tanks at which time it closes to allow full pressurization of the tanks.

For the G8299 with the dual motors, both motors can be started simultaneously for rapid pressur- ization. As with the G8298, the 2.5 HP pump is fit- ted with a cold-start valve which will stay open until approximately 20 PSI is reached in the tanks. This will allow the compressor to lubricate properly without straining the motor and pump.

Depending on the volume of the air usage, it is often adequate to recharge the system during operation using only the 2 HP pump taking advantage of its lower RPM and quieter opera- tion.

All of the compressors are equipped with a 150 PSI safety relief valve which will discharge air from the tanks if for any reason they should become over-pressured. See Figure 3. These are preset valves and are not adjustable.

Relief Valve

Fig 3. Pressure safety relief valve.

These compressors are also equipped with ther- mal overload breakers which will trip if there is excessive load on the motors which causes a heat buildup. In the event the breaker shuts the compressor down, wait a few minutes for the unit to cool down, then press the reset button shown in Figure 4.

Thermal

Overload

Switch

Fig 4. Thermal protection typical placement.

G8297/G8298/G8299 Air Compressors -9-