The FRP fan is located at a relatively high position and cannot directly exhaust the atmosphere. If direct exhaust, the pressure difference between the air inlet and the air outlet will be too large, resulting in overload of the FRP fan. In order to ensure a high vacuum, it is necessary to ensure the space between the rotors of the FRP fan.

Before using the device, set the front stage fan. Start the device after the pressure in the system is absorbed by the front stage fan to avoid overload. The front stage fan can be a vacuum fan that exhauts air directly, such as slide valve vacuum fan, water ring vacuum fan, reciprocating vacuum fan, rotary vane vacuum fan.

As the rotor of the FRP fan is constantly turned over, the inhaled gas from the air intake is drawn into the space between the rotor and the fan housing, and then discharged through the air outlet. Because the space is completely closed after inhalation. Therefore, the gas in the fan chamber does not shrink nor expand, but when the top of the rotor rotates around the edge of the exhaust port, the space is connected with the exhaust side, because the exhaust side gas pressure is high, part of the gas is rushed back to the space, so that the gas pressure is constantly rising. As the rotor continues to rotate, the gas is expelled from the fan.

As mentioned above, if this phenomenon is found in FRP fan, it must be dealt with in time to avoid major failure.