WIP: Spray booth and cart in 48hrs, and less than $235

Alex,

Sorry about getting back to you so late.  I was searching through some of the literature, and I don't know any way of doing an actual measurement without some sort of equipment--either an anemometer or a pitot tube (We use magnehelics as continuous monitoring devices that measure in inches of water.)  As you suggest, you could do a theoretical calculation based on either velocity pressure loss or static pressure.  For purposes of performance, I would rather concentrate on the inlet side.  Although measurement is still not possible without some sort of equipment (or a really good knowledge of the fan specs and all the associated formulae), a simple smoke test would be the "quickest and dirtiest" method to assure adequate airflow and capture.

If you still need me to send any formulae your way, let me know.

Merry Christmas,

Gip

 Alex-Here is a link to a an article on the design of spray booths. Included in the article are tables to calculate static pressures and elbow to straight duct eqiuvalents. This link originally appeared in the Tools Forum on 10-03-2004 during a discussion on spray booth design. The article may help you calculate theoretical air flows. http://modelpaint.tripod.com/booth2.htm

Jim

Bgrigg, a roll of paper, eh?  I was thinking of trying to get a piece of light blue flannel fabric to cover the grate, and using fresh butcher paper, or white flannel as a backdrop.  I swiped a piece of thin white flannel and hung it over the fluorescent lights. It seems to work well enough as a diffuser. I took a couple of pictures playing around with it so far, and liked having the horizon in the image, but if that's a no-no in photography, things can change. I'll post the test pics up as soon as my camera battery is charged.  

Nam, thanks for the kind words, and the offer to help with my data...I think I've got it now...Fortunately, (or unfortunately, depending on how you look at it)  I've had 2 years of fluids and thermo engineering classes in recent history, so I already know how to find my theoretical airflow, with and without head loss.  You actually like the bright lights in your spray booth reflecting on the metal??  I tried it, and it was way too bright.  So, butcher paper it is, at least for me!

Gip, thanks for getting back to me.  I've got plenty of formulas, I was just wondering if there was some sort of field test I could do to get a rough estimate of flow rate. I've sprayed some non-hazardous, but smelly things into the booth, like Windex, Vinegar, dyed water, and I never smelled them at all, and all of them got sucked in quickly.  I'm thinking I may need to put a rheostat on the fans so I can control their speed. Otherwise, the fans may pull the paint away before it ever reaches the model.

Hi Jim, thanks for the link...I already knew that stuff, but a refresher is always nice.

I think the next thing I need to do is to hang a small Purple-K (A/B extinguisher) near the spray booth, and mount the plexiglass lid. Then I'll look into making a drying booth function as well. Once all that gets completed, I'll tackle the circuitry side of things.  I'd like to end up with a control panel that has a rheostat for the fans (that's gonna take some doing, as I think they are binary...), and individual switches for the fluorescent light, a temperature controlled incandescent light for heat, a compressor switch, and possibly an emergency kill-button.

I like to design and build things...did I mention that?  Almost like I should've been an ME or something...

Anyone have any suggestions or see anything I've missed?  Thanks for looking!  I'm going to start a new thread in Tools, as I think the original challenge is complete.  Now I'm just tinkering...

Cheers,
Alex

 

NP about the airflow Alex! I knew of your background. I've learned much here about my OWN trade!

My suggestion would be a handy shelf....one inside and maybe one outside the booth......not sure of your countertop, but shelves are handy!

My eyesight sucks so badly.....aiming the lights upward and reflecting onto a cardboard surface works out very fine.

Nice work!

Well, Well! That's an eye opener and no mistake.

Superb idea and execution.

Cheers,

Von Buckle