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Spray Booth Exhaust

Spraying Glaze Spray Booth Over Spray

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#1 MikeFaul

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Posted 15 October 2013 - 04:26 PM

I have a 36" Paasche spray booth with an 1100 CFM exhaust. Glaze is making its way pass the interior filter and is being expelled through the louvered exhaust. The aerosol is waifing into the the neighbor's lot and hitting his property. As soon as I was notified I stopped spraying glaze and contacted our HVAC company to see if there was anyway we could fabricate a baffle, ductwork, and a secondary filter to stop the overspray. But, this will take days...

 

I was wondering if anyone out there has had to deal with a similar issue and found a working solution or even an interim solution we could use to get our glaze operation back online...

 

Thanks...

 

Mike



#2 JBaymore

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Posted 15 October 2013 - 04:58 PM

Man.... you do NOT want any "authorities" to get involved with this.   (Make "nice nice" with the neighbor....and don't spray until you have it solved.

 

If they call the state DEQ.......... you have a REAL expensive mess on your hands. (I used to be the Heath and Safety Coordinator for our college... and was the chair of the H+S committee for 7 years.)

 

Likely you'll have to add HEPA filtration to the flow... and that will require a fan upgrade to handle the much higher duct static pressures it will create to get the capture volume correct for the studio users.  Call an industrial HVAC guy..... this is likely not a do-it-yourself solution.

 

best,

 

.........................john


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#3 bciskepottery

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Posted 15 October 2013 - 06:53 PM

Remember the olden days when my mom would attach an old nylon stocking to the end of the dryer exhaust to catch lint.

 

Maybe try a better quality filter . . . the studio I use to spray at used the old cheapo filters -- the 3 for $1.00 kind but some of the anti-allergen might do a better job.

 

 

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#4 JBaymore

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Posted 15 October 2013 - 07:04 PM

This isn't drier lint!  The problem is that the stuff being exhausted contains a high percentage of a SERIOUS pollutant.  SiO2 is the BIG issue here.....in pretty much all glaze recipes.  It's a known human carcinogen, and there are various laws and standards that cover this stuff.  Putting that airborne out into the general environment and particualry potentially exposing someone else to this is a big potential issue.

 

And when organizations like the DEQ get involved... they usually start looking as all manner of OTHER things around the studio.

 

best,

 

.......................john


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Professor of Ceramics; New Hampshire Insitute of Art

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#5 bciskepottery

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Posted 15 October 2013 - 08:04 PM

Glaze is definitely not lint and, no, you would not want to use a nylon as a catch . . . which is why I suggested a better filter.  Actually better than the one pictured is one we cut from a piece of "cut your own size" filters.  They were far more dense (and thus better at trapping overspray) and washable so they could be hosed down (in a catch bucket, of course) and reused.  But the solution seems to be a better, more dense filter . . . such as a HEPA. 



#6 JBaymore

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Posted 15 October 2013 - 08:51 PM

HEPA is the only filter that likely will satisfy a regulatory agency.  And since it is the sub-micron particles that are the issue here... they will go right through any other filter material.  The otehr filters just stop the big stuff.

 

LUCKILY....... this is wet glaze spray, not a dry dust collection system... so a good portion of the material is getting onto the first stage filter right in the booth as a wet slop stuck on the surface.  But as that dries, or if dry residue is left on the surface and the vent is turned back on..... pretty good bet that some of the old dry glaze tiny particles are getting pulled through that first filter.

 

The only way to know what is going on here is air quality testing of what is coming out of the system.  Solutions might be simple, they might not.  But since there is a COMPLAINT ..... it changes the level of due diligence that likely should be used.  Otherwise the "wrath of god" may get called down by a disgruntled neighbor.

 

I've seen it happen. A good while back here in NH the EPA went on a salt kiln witch hunt and he FDA went on a lead glaze witch hunt.  Single operations started it in not handling complaints well..... and in the end it affected a LOT of potters.  And there have been other such stuff I've seen.  Don't ask me about schools getting many ceramic operations shut down for up to a year.

 

best,

 

.......................john


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Professor of Ceramics; New Hampshire Insitute of Art

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#7 MikeFaul

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Posted 15 October 2013 - 09:18 PM

Our neighbor is a really nice guy and very understanding, but there is zero upside in trying to push that and resume spraying. The right thing here is to properly filter the booth. Paasche was closed this afternoon, so I'll call them in the morning. I'm thinking an inline HEPA is the way to go and possibly replace the dry air booth with an aqueous / water booth that captures the material and maintains it in solution. Either way, I'm out a sack of money to maintain our look...

I'll call the managing director at The Work House Ceramics Shop too... They have a Paasche and they might have a better filtration system...

John's right... The risks of not doing the right thing are catastrophic... And, even if they weren't, it's just plain nasty rude to spray even inert material on someone else's property.

#8 Mark C.

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Posted 15 October 2013 - 09:22 PM

A fine spray (waterfall/mister of recirculating water) that you can filter out now and then may work.

The hepa filter is what I use in my air filtration system-not sure about them in wet conditions?

Mark


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#9 MikeFaul

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Posted 16 October 2013 - 08:27 AM

Well it looks like we may have a solution... I found a spray booth filtration company that's sending replacement filter material. They also said the duct length out of our booth is way short for the blower capacity, and that's probably at the heart of the problem. The material is being sucked through the filter at a high velocity and doesn't have time to get caught before discharge to the outside.

 

So, they suggested trying the new material and erecting a target to catch any overspray, run a test, check the target. If there is any material collecting on the target, then elongate the duct and place a secondary filter inline on the duct extension. They calculate I can extend the ductwork another 15 feet and still have a functional system, we only have 8 feet to redirect to the rear of the building and away from our neighbor. If he doesn't object to the aesthetics, we'll go ahead and run the duct extension to the rear of the building. 

 

The new filter material is not that expensive... Only about $5.50 per 36" X 27" sheet, they suggest doubling up, but taking care to avoid too much negative pressure because at 1,100 CFM this particular blower is not that powerful. The new filter bags will need to be changed weekly during regular glazing operations. So, we're looking at about $25.00 per month additional expense.



#10 JBaymore

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Posted 16 October 2013 - 09:37 AM

There you go!  An economic sting...... but not all that bad.  Glad it appears to be relatively simple. Good on ya' for taking it seriously and looking for a professional solution.

 

One "lesson" that others can take from this story (duct is too short for the installation) is that sometimes just because you have a piece of equipment it does not mean that it is necessarliy operating correctly.

 

best,

 

.....................john


John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#11 MikeFaul

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Posted 16 October 2013 - 09:50 AM

There you go!  An economic sting...... but not all that bad.  Glad it appears to be relatively simple. Good on ya' for taking it seriously and looking for a professional solution.

 

One "lesson" that others can take from this story (duct is too short for the installation) is that sometimes just because you have a piece of equipment it does not mean that it is necessarliy operating correctly.

 

best,

 

.....................john

Good point... It would seem, that if you're spraying with a booth, and I believe you should be using a booth if you spray, the ductwork is part of the catch system. The material not caught by the filter(s) should have sufficient time to settle inside the ductwork and / or cling to the walls of the duct. The duct should be fashioned professionally to allow for a disconnecting of the duct and cleaning of the interior of the run. The frequency of cleaning is dependent on the quality of your filter and the frequency with which you change the filter. Periodic inspection of the duct and blower not optional.



#12 JBaymore

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Posted 16 October 2013 - 10:45 AM

In my kiln design course I spend a bit of time talking about industrial type ventilation...... and one of the points I try to make is that you can have a honkin' big fan stuffed in a wall somewhere and it is roaring away creating a lot of noise........ but it might be moving very little air if you haven't accounted for the OTHER ventilation systems in play in the space (active and passive), the supply of make-up air, and the various pressure drops involved in air movement through openings, rooms, ducts, and such. 

 

And that it can screw up those other ventialtion systems and things like kiln draft too.  That it all is interacting and must be considered as a totality... not single units.

 

Potters in general seem to like to do a lot of "do-it-yourself solutions"..... and that is admirable. (Often it is out of economic necessity.)  But sometimes.......  ;) ...........

 

best,

 

...........................john


John Baymore
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Professor of Ceramics; New Hampshire Insitute of Art

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#13 JBaymore

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Posted 16 October 2013 - 10:50 AM

 Periodic inspection of the duct and blower not optional.

 

Absolutely true.

 

The flow thru a pipe  (duct, chimney, flue) is in part dependent on the nature of the surface of the material it is made of.  As the duct gets deposits on the inside, it changes the flow characteristics.  So a build up of "fuzzy" glaze materials on the inside is very likely decreading the airflow through the duct by raising the resistance to flow along the surface... and causing increased turbulent flow along the wall surfaces instead of what is called laminar flow.  (The smaller the duct diameter, the more this comes into play.) 

 

So if you let it build up, your system is slowly and almost imperceptiably losing effectiveness.

 

best,

 

.......................john


John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#14 MikeFaul

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Posted 19 October 2013 - 09:11 PM

The new filters showed up, and in replaced the old ones, the meter on the booth says air flow has been halved, but still within operational norms. The HVAC guy suggest a 90 degree turn on the exhaust duct to point it toward the ground and adding a 12x12 secondary HEPA filter... Going to do that as well.

#15 JBaymore

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Posted 19 October 2013 - 09:17 PM

I'll be interested to see what the 90 ell and the HEPA filter do to the airflow.

 

best,

 

.......................john


John Baymore
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Professor of Ceramics; New Hampshire Insitute of Art

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#16 Mart

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Posted 20 October 2013 - 04:56 PM

The new filters showed up, and in replaced the old ones, the meter on the booth says air flow has been halved, but still within operational norms. The HVAC guy suggest a 90 degree turn on the exhaust duct to point it toward the ground and adding a 12x12 secondary HEPA filter... Going to do that as well.

 

Why not build a small "water curtain" at the exit. You probably only need a old shower head and a garden hose. No need for a fast flow (waste of water)



#17 Mark C.

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Posted 21 October 2013 - 12:40 AM

My hepa air filter added to two other filters cut down my air flow-The hepa is sandwiched between the two-the first gets most of the dust and is cheap to replace. The hepa is next the 3rd is a cloth pleated bag built into unit-pricey to change out .


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#18 Mart

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Posted 22 October 2013 - 11:44 AM

MikeFaul, what is the MERV rating for your filters?
I like to build a spray booth soon. I am probably going with water curtain on the back wall. Sounds like this design will save me from most of the trouble you are in right now.

#19 MikeFaul

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Posted 22 October 2013 - 12:59 PM

 

The new filters showed up, and in replaced the old ones, the meter on the booth says air flow has been halved, but still within operational norms. The HVAC guy suggest a 90 degree turn on the exhaust duct to point it toward the ground and adding a 12x12 secondary HEPA filter... Going to do that as well.

 

Why not build a small "water curtain" at the exit. You probably only need a old shower head and a garden hose. No need for a fast flow (waste of water)

 

 

 

 

The new filters showed up, and in replaced the old ones, the meter on the booth says air flow has been halved, but still within operational norms. The HVAC guy suggest a 90 degree turn on the exhaust duct to point it toward the ground and adding a 12x12 secondary HEPA filter... Going to do that as well.

 

Why not build a small "water curtain" at the exit. You probably only need a old shower head and a garden hose. No need for a fast flow (waste of water)

 

Good question... I bought a Paasche spray booth, and it's not designed to accommodate a water curtain within it's structure. The booth is approved by OSHA and the EPA. So, I would have to modify the booth to provide for an internal water curtain. That means I have to run plumbing to that side of the building or a hose over my studio floor. Since the studio has pine cladding on the walls we would have to rip out the plank, run the plumbing, buy new plank, sand and pickle the plank, and install back on the studs. Plus we would have to get permits for all of that and I just don't want to go through that process again. 

 

I could put a water curtain on the exterior just off of the louvered panel outside the building fairly easily. But, that means running water hitting the ground, pooling, and running off into the neighbor's property. New EPA regs make waste water run off to adjacent properties problematic. So, the best solution is to properly filter the material out before its ejected from the building.



#20 MikeFaul

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Posted 22 October 2013 - 01:03 PM

I'll be interested to see what the 90 ell and the HEPA filter do to the airflow.

 

best,

 

.......................john

I replaced the filters and doubled up on the new filter, and the air flow went (comparing clean filter to clean filter) from +0.5 inches of water column to +1.0 inches of water column, or the air flow was cut in half. As measured by the manometer...






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