Hi guys, I have seen quite a few good designs posted in this forum, and I know that there are some very knowledgeable people here when it comes down to airbrushing and airflow. I'd be in your debt to get some advice on this topic...
I'm looking for some advice on selecting a blower motor for my home-made spraybooth.
It is a cross-draft design with an interior of about 30" wide x 25" tall x 20" deep. The basis for fume extraction is a 20" x 25" furnace filter installed in the rear of the booth. It is very similar to the design specified on
this website (click). I just increased the dimensions a little.
I am also using the CFM and static pressure values that the author uses. The trouble is, I really don't know what these values mean, since I have no experience with them. He states 100 cubic feet per minute through the booth as an industry standard. Is this correct? Is this a noticeable airflow?
Back to my specs and the author's guide for calculations.....
Using the 20"x25" furnace filter as the interior size and multiplying by 100 CFM, I come up with a value of 347 CFM that needs to move through my booth (1.67'x2.08'x100). Secondly, I anticipate using around 20 to 25 feet of vent tube, once all the angles are taken into consideration. By using 4-inch duct, I would apparently have a value of around 1.2 static pressure in the ductwork. 5-inch duct calculations yeild a static pressure value of around 0.4 in the ductwork. So, I think I will be using the 5" duct, since I have not seen any motors with specifications beyond 0.8sp.
Ok, boring calculations aside, here's my dilemma. I'd like to purchase a Dayton blower to use as the extraction motor. The author of the article recommends 4C444 and 4C445, as they are listed in the Grainger catalog. Truth be told, I am really stuck between the two. At the 0.4sp I calculated, the 4C444 seems underpowered, and the 4C445 is overpowered when I use the 347 CFM value of airflow. I'd hate to get too small of a motor and have my booth be essentially useless. On the other hand, I'm afraid of getting too powerful of an airflow, and having some sort of swirling vortex inside my painting area.
I'm looking for suggestions from people here who have built their own booth, or from those who have experience with airflow requirements in painting. I'm leaning toward the 4C445, but am just unsure. As far as the blower motor goes, what course of action would you recommend?