Is a totally enclosed motor different from an "explosion proof" motor, other than the label and the $200 + difference in price? What do you use in your finishing rooms? What is a good brand and good deal on a 16 inch exhaust fan? My finishing room is 12' x 12' x 10' high, with a window in it that I would like to exhaust out as opposed to mounting a fan through the wall. I shoot mostly WB, but I also shoot a good bunch of alchohol base shellac.
From contributor R:
Totally enclosed fan cooled (TEFC) motors are quite different than explosion proof. You would not use a TEFC motor to replace an explosion proof. That said, the motor needed depends on the fan you have. If the motor will be in the exhaust air stream, you need an explosion proof motor. These are usually direct drive fans with the blade mounted on the motor shaft. If your fan is belt driven with the belt inside a tube that extends to the outside of the fan, a TEFC motor will be fine. These fans are tube axial.
The speed of the air that you should move through the booth is 100 feet per minute (FPM). Your booth would be 12 x 12 x 100. A 16" fan will not move that kind of air. The fan should be about twice that size and have about a 15,000 CFM at 1" SP rating. The less air moved, the more likely over spray will land on your product.
For example, if you take an automotive booth that is 26' long, 15' wide and 10' high, the 100 FPM would suggest that you need 15,000 CFM for this booth. Once you stick a car in the booth the cubic volume of air is greatly reduced and the airflow rate is at a higher FPM than if the booth was empty. This is why many booths have a frequency control unit for the fan speed. If you stick a minivan in a car booth you have to turn the fan down or it's too windy. The minivan reduces the opening by 65-70 sq ft which would result in 170+FPM with a 15000 CFM fan.
In a parts booth or woodwork booth you need to change the air over 3-4 times per minute including losses. If you have a 20' long 10' wide and 10' high booth you have 2000 cubic feet of air. For this application you want a fan that will move 8000 CFM at a full load of static pressure that includes ductwork and filters. If you shop around for a factory made booth of this nature you will see that most have fans from 7500 to 12,000 CFM at 1/2" SP.
My booth (home made) is 20'L x 12'W x 9'6"H and I run at 6000 CFM @ 1" SP for crossflow or semi-downdraft. Since I do mainly cabinets, flat pack and other basic wood stuff I don't need a mega fan like the 28,000 CFM one from my old truck booth.
Find some specs for a UL listed booth and follow what they have as a baseline. Also study the dynamics of the airflow to ensure that you have 100 FPM in the main working area. If you are spraying parts and stand directly in front of the filter bank you shouldn't get overspray on your finished parts.