Choosing & Replacing a Paint Booth Fan A Complete Guide
Paint booths typically last for a very long time without the need for any major repairs. After all, they’re mostly a sheet metal enclosure along with a chamber that holds filters in a fan that pulls air through the enclosure to properly exhaust overspray and harmful VOCs. If you have an air makeup unit they can often have additional issues from time to time but that is not what we will consider in this article. One of the few repairs you may have to occasionally do to a paint booth is replacing its fan. In this article we will cover what you will want to know when you’re considering replacing your paint booths fan.
Factor 1-Do you have a true paint booth or a modification of a true paint booth
Paint booth fans consist of a tube axial fan along with a motor to drive the fan assembly. Paint booth fan motors primarily come in two different styles, explosion proof or totally enclosed. A totally enclosed motor is relatively protected from allowing any flammable chemicals from contacting electrical sources, but it is not completely isolated from flammable substances. In contrast, and explosionproof motor has significant modifications that make it protected from allowing any flammable substances from contacting an electrical source within the motor. It is important to know whether you have a true paint booth or modification of a true paint booth like an exhaust chamber only because it will contribute to whether you consider and explosion proof or totally enclosed motor. If you are using a true paint booth that has been designed by manufacturer a totally enclosed motor will typically be what was originally used for the paint booth fan motor. This is because the enclosure will prevent flammable substances from being able to come in contact with the electrical portion of the paint booth fan motor as the motor will typically be isolated from any flammable spray by the booth enclosure. However, if you are using a exhaust chamber only or a different spray area design, we typically suggest considering and explosion proof paint booth fan. Using an explosion proof fan will be slightly more expensive, but the electrical components of the fan will be better isolated from being exposed to any flammable substance. This is important because since you will not have an enclosure that better guarantees no flammable substance like solvents are able to migrate from the spray area and find a way to the electrical portion of your booths motor. By using an explosion proof fan the risk of the fan causing ignition of a flammable substance are substantially reduced compared to using a totally enclosed fan motor.
Factor 2-The CFM requirements of your paint booth
if you need to replace an existing manufacturers paint booth fan, you will want to check in your manual that came with the paint booth. You should be able to find specifications on the motor including horsepower, electrical supply, and potentially CFM needs. The combination of tube axial fan and the motor that you use to run the fan will need to be able to match the original CFM requirements of the paint booth. While there are general rules to the CFM that paint booth manufacturers achieve which you can learn more about here, it is ideal to match the original fans specifications rather than use the general formulas to determine the CFM that you need from your paint booth fan. Typically most paint booths factor in resistance equivalent to .375 inches of water column, which is the amount of resistance you will typically be evaluating when determining that a potential fan will provide sufficient CFM. If you’ve made modifications your booth or have long runs or multiple elbows your fan may need to be chosen based on a higher static resistance. That is why is usually ideal to know the original fans CFM specifications and to know at what resistance the CFM requirement was calculated at as it will help ensure the fan you select is the proper size for your booth.
Factor 3-Your spray booth’s duct dimensions
Most paint booth fans will also specify a size of the fan along with other key dimensions which will typically include ring to ring, inside diameter, mounting bolt, and outside diameter measurements. These can be critical because if you’re trying to simply match the original duct with the fan you’ll need to know whether these dimensions all line up. To better understand each dimension see below.
Ring to ring
Ring to ring references the total height of the paint booth fan. This can be important if you’re trying to replace a paint booth fan that the duct has to remain the exact same height after the fan is replaced. This is a common situation if you have an elbow directly after the fan that is close to an outside wall or similar situations. Essentially if you want to make sure that the duct does not change at all you want to make sure the ring to ring size of the new fan is the same as the fan your replacing.
Inside diameter
The inside diameter is how wide the fan is from the inside edge to the far inside edge of the fan. It is essentially a way to know that the fan will properly sit inside your paint booth duct. If the inside diameter is significantly different than the internal diameter of your paint booth duct you may need to evaluate a different fan.
Mounting bolt
The mounting bolt measurement determines the space from one bolt to the one directly opposite across the fans face. This measurement is important to match if you do not want to have to potentially replace the mounting rings that you use to secure the duct to the paint booth fan. If you do not mind replacing the rings you will just want to make sure that the new rings you use will have mounting bolt holes that match the specification of your tube axial paint booth fan.
Outside diameter
The outside diameter references total distance from the farthest edge of the fans face to the furthest edge of the opposite side of the fans face. This measurement is important because if the fan is extremely wider than your duct it may not properly seat inside the duct creating airflow problems.
Factor 4- Your Electrical Supply
A final factor to consider is the electrical supply that you have available to feed your paint booth fan motor. The most common paint booth motor is a tri-voltage motor which can use 208/230/460 V. If you need 575 V you’ll typically need a different paint booth motor that is designed to accommodate high-voltage use.
Summary
There’s a lot involved with replacing your paint booth ideally should match the CFM requirements, your duct, your electrical supply, and the type of booth that you are using so that you can select an appropriate tube axial fan and motor replacement for your paint booth. If this is all confusing and you want help replacing your fan we will give you a free consultation to help determine which fan is right to replace your existing paint boosts fan. You can also see our paint booth tube axial fans here or our paint booth fan motors here.