Spray booth noise

Tools, Techniques, and Reference Materials Painting and airbrushing
1

There have been countless threads about spray booths, but one topic which I’ve virtually never seen is that of noise.

This hit home with me when I recent;y threw together a small proof of concept booth with a axial fan. Didnt sound like a crazy idea since booths from ArtoGraph and Paasche use such fans in their designs. I got my hands a decent 150x38mm 130cfm fan…which I’m glad I didn’t actually throw serious money or effort at because its high pitched screech is unbearable. No way could I sit for 20-30minutes doing fine work with that thing right in front of me.

rpm is the vital factor. As we shrink size, rpm (which = noise) has to go up in order to maintain cfm. conversely if we want to keep a low rpm (which = quiet) we need to increase fan size in order to achieve decent cfm.

The proverbial Dayton Shaded Pole (or PSP’s which seem to be replacing them) have long been choice pieces for hobby spray booths. They come in all manner of size and CFM though. Looking at specs I notice they tend to be either 3000ish rpm or 1500ish. To anyone who went this route, which rpm is yours and what do you think of the noise?

I really wonder about commercial hobby booths (the few decent ones that is). Paasche HSSB models and the well known ArtoGraphs use axial fans, boasting 270-350+ cfm! I would think they must be hideously loud. Anyone with one of these care to share the model of motor in them so we can find out the spec? Badger I think has gotten out of the market, but their last one I know was a small (~3.5" inlet) 3000+ rpm Dayton churning out something like 167cfm. HAD to be whinny for something that size to move even that much air but I never had a chance to hear one (spray booth seem to be one of those things you mail order on faith 'cause no local store seems to stock them).

But I ramble. Anyway, I’m interested in any thoughts you may have, especially if you happen to be a Home Theater nut and have a Radio Shack SPL meter to share some real loudness measurements (since “…like a bathroom fan…” is about as ambiguous as it gets. :slight_smile: ).

2

size and RPM arent usually the culprits with noise, its the bearings you have to look at. Im running some pretty small fans in my computer at very high RPM and theyre whisper silent. But thats a computer fan. if you could rewire one you could have mains power for it but that would probly blow it to peices as theyre meant for 12v and under. battery power it maybe. but thats just my 2 cents.

3

I’ve got a 485 cfm Dayton shaded pole blower in mine, and it makes less noise than the typical household box fan. It is not silent but it a white noise and easily tolerated.

This is the blower

http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=1TDR7&op=search&Ntt=1TDR7&N=0&sst=subset

4

Aaronw: I built my spray booth 20 years ago I got my blower from one of the plumbing shop here in town,it came from WW GRANGER .Its a brush less induction motor that way you don’t have to worry about a fire or explosion caused by sparking motor brushes. it’s quiet motor there designed to be used as furnace blowers. The model I used is 4C447 hopes this helps you. aceses5[whstl][proplr]

5

Do you have a rheostat on your setup? How controllable is this fan? I have been thinking of upgrading my fan, and this looks like a good candidate!

Chris

6

Sorry to burst your bubble but those are not rated as “explosion proof” motors!

On the other hand I think that term is a little far fetched as the chance of causing a fire or explosion with a paint booth is very minimal as I have expounded on ad infinitum. ad nauseam.

7

Anyboby ever used one similar to this ?

http://airboosterfans.com/duct-fan.html

I’m considering one and would like some info.

8

Occupationally, an individual cannot be exposed to a noise source that exceeds 85dBA based on an 8-hour time weighted average without some sort of protective measures (engineering or administrative controls, and/or the use of personal protective equipment such as ear plugs, muffs, or a combination of the two). Many companies are creating industrial-type equipment that keeps sound pressure levels under that 85dBA criteria. Manufacturers may rate their products at a particular noise level, but variability in location, use, setup, etc. may cause a large swing in actual noise values experienced.

Interestingly, there are a lot of variables in determining how noisy (noise being defined as unwanted sound) a fan/booth setup is going to be. One of the posters on this thread has mentioned bearings, and that is true–more on that in just a moment (See f. below). A few of the other variables include the following:

a. How large is the area where the booth is going to be located? Smaller areas typically result in more (louder) noise.

b. Construction materials of the room. A concrete block basement is going to cause noise (particularly the higer frequencies) to ricochet, thereby amplifying the original noise source. Wallboard will have a more absorptive effect.

c. Booth size. A booth is a big box. Vibration (which is sound) can cause the booth to become a speaker depending on the sound frequency and booth construction (sheet metal or wood, for example)

d. Fan mounting. If the fan is mounted directly to the booth, vibration can be transmitted directly to the booth. A simple neoprene rubber gasket between the motor and booth can contribute substantially to reduced vibration.

e. Duct size. A 4" duct moving air at 5,000fpm is a veritable wind tunnel. The smaller the area, the higher the velocity, the noisier it gets. Increasing duct size can reduce noise.

f. Motor/fan maintenance. Using a fan/motor that has been used religiously for the last 20 years is probably going to be more noisy than a new one of the same model simply because the bearings may be wearing out. In addition, a fan blade is aerodynamic in design. Accumulation of paint residue reduces aerodynamic blade efficiency, but more importantly, throws the blades out of balance, which can cause a real racket–and cause bearing failure. Use of good paint filters can prolong the longevity of the fan.

g. The obvious: Fan size, rpm, rated airflow, and direct drive versus belt drive.

These are just a few of the variables that can cause noisy booths.

A good rule of thumb for those who don’t have a sound level meter at their disposal is called the “3-foot rule”, or “normal human conversation rule”: If you’re carrying on a conversation with another individual at a normal distance of about 3 feet, and you have to raise your voice to be heard over your paint booth, then the paint booth is probably exceeding the 85dBA noise criteria (this assumes reasonably good hearing in both parties). A good set of ear plugs is in order, or some sort of modification to your booth.

By the way, a good friend of mine owns an Artograph booth. It produces great airflow, and is very quiet.

Hope this helps some.

Gip

9

Nope, I don’t even have a proper on off switch, just the power strip that also turns on the light.

I would have no reason to reduce the air flow, so don’t see any point in a speed controller.

The blower doesn’t come with a cord though so you do need to get one, but that is only about $6.