Types of Paint Booth Exhaust

When spraying paint in a paint booth, you need to expel the fumes from the work area. In sufficiently high concentrations, the fumes will cause health problems and may even lead to serious injury. The fumes are removed from the area by use of an exhaust fan. This exhaust fan needs to be properly sized to move enough air out of the work area

There are many other types of fans exist and may be found in the industrial world, but in regards to the automotive refinish market, there are four main types that you will see.

1. Forward Curve Centrifugal Fan

A forward curve centrifugal fan or “squirrel cage” is used predominantly in the intake side of any paint booth or in aftermarket air makeup units that can be added to  spray booth after the fact (aftermarket meaning it was not manufactured or designed by the paint booth manufacturer). It is also used in commercial and residential heaters. This type of fan is used almost solely in intake units and not in the exhaust because it is built to handle clean air. A forward curve fan could not support being laden with the paint overspray if it were used in the exhaust side of the paint booth. Eventually, the overspray would cake up enough to diminish performance, throw the fan out of balance, or even break blades off the wheel. The forward curve fan is also preferred for most intake units because it is the quietest of all fans and delivers very powerful airflow for its size and weight. Since the air coming through the intake is delivered right to the paint booth workspace, the sound level produced by the intake fan is conducted right to the worker and noise level is a very important consideration when a paint booth manufacturer is trying to design a comfortable workspace.

2. Backward Inclined Centrifugal Fans

A belt drive double inlet fan has a shaft that runs through the wheel. The shaft is accessible on the exterior of the fan housing. Because of this, the manufacturer has the flexibility to design the motor to mount anywhere around the fan. The motor may be either inside or outside the main box or on either the left or the right side since the shaft protrudes on either side of the fan wheel. The motor shaft gets a pulley and so does the fan shaft. They are then connected with belts in order to provide rotation. When the unit is started, air flows into the center of the wheel from both sides (“Dual Inlet”) and the air is then expelled out the mouth of the fan.

3. Tube-axial fan

Most industrial paint booths, truck paint booths, and entry level automotive paint booths use the tube-axial fan as the fan of choice for the exhaust side of the airflow. This is mostly due to the low cost of the hardware and low cost of the installation. The fan itself is economic. It needs no additional housing and is simply installed in line with the paint booth or prep station exhaust ductwork. Most applications in the automotive and truck paint booth market use belt-driven tube axial fans however, direct drive versions do exist. Direct drive versions may require an explosion proof motor and are generally not seen in the automotive paint booth industry.

4. A Direct Dirve Single Inlet Centrifugal Plug Fan

A direct drive single inlet centrifugal plug fan has no shaft and simply has a coupling or “hub” on one side of the fan wheel that allows the motor shaft to hook directly into the fan wheel. When the unit is started, air flows into the open side of the wheel and is then expelled out the mouth of the fan. The term “single inlet” comes from the fact that the fan can only draw from one direction because the motor and mounting plate are blocking the other side of the wheel.

Application