Container spray booth build?

[Albert]

I am new to spray finishing - be kind..

I have been told to achieve quality spray finish you need quality spray guns, therefore I have been looking at fancy spraying guns but realised I need a proper booth to go with the proper gun.

My current compressor is Chicago Pneumatics CPRS10500, does 43CFM, its a 10hp with a 500 litre tank. The refrigerator and filter are Ceccato, they were spec'ed to match the compressor. I guess my compressed air ends are sorted.

I am planning to build my own spray booth using a small container type storage like the one below and extract the air from my existing dust extractor, the cost for this storage will be about $2500NZD. I have no room in my workshop. this will be sitting on my driveway next to the workshop.
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my questions are:

Can I use my existing extractor to pull air from the booth? Will the filters similar to the one below be adequate to catch most of the paint so it doesnt destroy my extractor filter? the extractor is a 4kw unit, the filter cost about $700NZD, the filter below measrues 1200mm x 500mm x 250mm deep.

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or do you recommend have dedicated fan for it? I may just use 2 of these portable unit, will my neighbour smell anything once I hooked up a fan to it? the cost for the fan is about $200-250 NZD each.

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Will I be able to have my spray booth built under $5000NZD and keep the neighbour happy? or can it be built more economically and still keep the neighbour happy?

What will I be spraying? I dont know at this stage. I am yet to find a suitable finishing product for the furniture I build. Probably shellac or water based polyurethane?

Thanks.

[Cliff Rogers]

Good ideas, I reckon that the dust extractor may not shift enough air & I would be worried about the filters.

These things are always a problem in suburbia.

I'm in the bush so I don't have problems with noise or dust upsetting the neighbours.

My biggest problem is the air intake, not the extraction.

The air up here can be VERY wet, we are just below the cloud base & sometimes we are just above the cloud base so anything that draws air in brings cloud/mist in with it.

[Chris Parks]

Albert, have you thought about the supply of air needed and how you are going to filter it? Most spray booths these days are down draught and I believe use water to trap the solids. I would be wary about any neighbour reaction to the exhaust as this is, in Oz at least, a very closely regulated thing due to the emission problems. I would be taking a very long hard look at all the issues as spray booths are not cheap for good reasons.

[BobL]

Definitely don't use your dust extractor or the fumes will clog your DC filter.

In terms of fans I would look at using squirrel cage fans (SCF) as they are high volume and much quieter than axial fans.

It depends on what volume of spray painting you intend doing.

If you are doing it full time then you will need something serious like Chris suggests.

If you are only doing occasional sprays then a specific paint stop filter like Vokes media will probably be sufficient.
See :: AES Environmental online :: Roll media (http://www.aesenvironmental.com.au/roll_media.htm)
While its very effective I would still not trust it to prevent DC filters from clogging

There is nothing really fancy about paint stop media other than it is a low resistance graded density filter medium.
Similar and cheaper versions can be found that are not specifically for paint that work almost as well.

I have a small welding bay fume hood that I sometimes use as a spray booth.
It uses a single 0.75 cubic metres per sec SQF and when painting I place a square foot of AES Environmental H media in front of the fan inlet and it seems to capture all the paint spray i.e. can't see any colour getting past that. The filter lasts for about 10 small paint jobs and then needs to be chucked away. Fortunately I have a big roll of the stuff that should last a lifetime. I reckon most of the clogging comes from dust in the air sticking to the paint rather than the paint itself.

Something you will need to keep in mind is pressure losses due to the paint load
When new the 2" thick paint stop media has a pressure drop of 35 Pa at 2.5m/s
2.5 m/s x 0.36m^2 (or 2 ft x 2ft) of cross sectional capture area ~1 m^3/s (About 200 CFM) which would be possible with two smaller or one larger SCFs and the 11 Pa plus the additional load cause by the dried paint should be easily coped with by the fans.

[ian]

Hi Albert

What sort of system are you considering? HVLP or LVHP?

What material will you be spraying? Especially in regards to the solvent.
Some represent an explosion risk unless the electrics in any fan are protected -- the cheap axial flow fans may not be suitable for some solvents.

Perhaps investigate professional finishers in Auckland

[woodPixel]

Are you spraying just furniture?

Thats a mighty setup for an individual. I'd be interested to know how it all goes.

I spray nitro, oil and water paints, and poly in my impoverished setup..... a market gazebo/tent with the fine mesh sides! A remote breather so fumes don't do me in and a garden hose in the summer for dust :)

Keeps out all the bugs, dust and specs aren't an issue either... but then again I'm not refinishing Louis XIV bombe!

more pix as you progress please! :D

[Albert]

I am going to put the filters at the intake grills, just like the ones they use at the professional booth? I have thought about down draught and use water to trap the solids/paint but this is quite tricky. over here it is very strict as well, been researching online on this...

[Albert]

Definitely don't use your dust extractor or the fumes will clog your DC filter.....coped with by the fans.

Thanks Bob. I have ruled out the use of my dusty. am trying to find good filtering media and the resistance lost, wouldnt want to draw too much air so the paint just float away as I spray and dont want to draw too little...

[Albert]

Hi Albert

What sort of system are you considering? HVLP or LVHP?

What material will you be spraying? Especially in regards to the solvent.
Some represent an explosion risk unless the electrics in any fan are protected -- the cheap axial flow fans may not be suitable for some solvents.

Perhaps investigate professional finishers in Auckland

I will be spraying HVLP, material wise I think it will be limited to water based paint for now but I would like to build it so I can paint other stuff, yes they will need to be explosion proof... I know there are explosion proof fans but not so sure how the shed can be built to "explosion proof"

I had a look on the fans, itself could cost anywhere between in the region of over $2000-$4000 brand new.

Might try second hand.

[Albert]

Are you spraying just furniture?

Thats a mighty setup for an individual. I'd be interested to know how it all goes.

I spray nitro, oil and water paints, and poly in my impoverished setup..... a market gazebo/tent with the fine mesh sides! A remote breather so fumes don't do me in and a garden hose in the summer for dust :)

Keeps out all the bugs, dust and specs aren't an issue either... but then again I'm not refinishing Louis XIV bombe!

more pix as you progress please! :D

Yes I am just spraying furniture, just trying to do it right to minimise the effect on the environment... live in a residential neighbourhood.

I wish I can set it up like yours but I cant! I need a permanent setup so I can walk in and start spraying.

[Arron]

This is just a thought, so it might be irrelevant depending on your experience level, but....

It seems to me that building a spray booth when you have limited experience of spray painting and don't even know what products you will be using is a bit fraught. Would it make sense to hire a booth for a few times first. Here in Sydney you can hire a booth for about $100 per hour, and naturally it's discounted for a full day. You could do that for a few times till you have a feel for it, then build.

In some cases you can even hire a spray painter as well for $90 per hour. That seems like a good idea because spray painting has a learning curve and just seeing it done and being able to discuss with a expert rockets you up the learning curve.

Or you may even decide not to turn your home into an industrial site and just rent one when you need it, ongoing.

Cheers
Arron

[BobL]

I will be spraying HVLP, material wise I think it will be limited to water based paint for now but I would like to build it so I can paint other stuff, yes they will need to be explosion proof... I know there are explosion proof fans but not so sure how the shed can be built to "explosion proof"

I had a look on the fans, itself could cost anywhere between in the region of over $2000-$4000 brand new.

Might try second hand.

The motors themselves don't need to be explosion proof if they can be separated from the fans like this.
This chemical fume hood ventilator is considered explosion proof because the motor is not inside the fan, the fan body is non-sparking (PVC) and the squirrel cage (in this case is metal) but it could also be plastic.
Its about 50 years old and I found this in a skip at work following some lab renos. T
here were at least 3 others there that I could not get at.
It's only 600 cfm and it had a 3P motor which I replaced with a SP clothes drier motor
I gave this blower to my son for his shed as he does a bit of spray painting of small stuff - he does not bother to filter as the volume of paint he uses is very small.
The whole unit sits in a lean to outside his shed and the horizontal inlet goes through the shed wall.
http://www.woodworkforums.com/attachment.php?attachmentid=313357&d=1399895277

[Albert]

This is just a thought, so it might be irrelevant depending on your experience level, but....

It seems to me that building a spray booth when you have limited experience of spray painting and don't even know what products you will be using is a bit fraught. Would it make sense to hire a booth for a few times first. Here in Sydney you can hire a booth for about $100 per hour, and naturally it's discounted for a full day. You could do that for a few times till you have a feel for it, then build.

In some cases you can even hire a spray painter as well for $90 per hour. That seems like a good idea because spray painting has a learning curve and just seeing it done and being able to discuss with a expert rockets you up the learning curve.

Or you may even decide not to turn your home into an industrial site and just rent one when you need it, ongoing.

Cheers
Arron

Thanks Arron, I have considered hiring a spray painter to spray paint my product, the painter has a proper booth setup but the cost is exorbitant - I guess it is because its labour intensive?

It is a good idea, to rent a booth first to see how I go then build.

or not spray paint finish my product at all.

[Arron]

or not spray paint finish my product at all.

No, you need to spray. Nothing in a small scale woodwork business is more profit-enhancing then spray-finishing.

Cheers
Arron

[Albert]

exactly... I have already invested in some good gear for the compressor setup, I dont mind to spend extra $$$ on a proper shed, a fan and filter, if my initial budget of $5000 is not enough to obtain optimal solution (optimal as in minimum disruption to the environment, been looking at regulations in NZ they are all aimed at industrial operations, you can spray paint at home as a hobbyist but you can not spray paint like a full time job)

I have been asked too many times by my client why is the work semi finished, ie, not painted - I had to makeup reasons such as, we let the client to choose their finish as most clients would like to do some DIY themselves...etc etc.

[ian]

Hi Albert

looking at your other posts, your "shed in the garage" is really a small scale industrial set-up -- though we both know it's just a well funded "hobby".
So I can't see you settling for anything less than small scale industrial for your spray finishing.

However, you should seriously look at contracting a professional to do your finishing. While the rate might appear exorbitant, in reality it should represent a fraction of the value add from applying a spray finish. If the professional would charge you $200 to apply a finish, you should be looking to cost your own finishing at a similar (if not higher) rate, which at a cost of $200 per item should represent a $400 (or more) increase in the piece's value. If the client is not prepared to stump up for the additional value (i.e. cost to them) then you have to ask why you would invest in a booth.
If the client is only prepared to pay $100 more for a finish that costs $200 then accepting only $100 means that you are going backwards.

[ian]

I've googled a bit about spray finishing ...

https://gfsboothblog.com/2013/03/26/air-changes-vs-air-velocity-gauging-paint-booth-ventilation-performance/

"It is more common for the ventilation performance of a spray booth to be specified by the average velocity through the booth or in the vicinity of the painter and product. From the design velocity you can calculate ventilation flow rates and air changes.
For example, if your booth is 16 feet wide by 14 feet tall and is a cross draft design, typical velocity in the booth would be 100 feet per minute (fpm). The total flow through the booth would be 22,400 cubic feet per minute (cfm) (16 x 14 x 100). The volume of the booth is 8960 cubic feet (16 x 14 x 40). The air changes can be calculated by dividing the flow rate by the volume. In this example, the air changes would be 2.5 air changes per minute (22400 / 8960).
These sorts of numbers equate to the air flow velocity in the one spray finishing booth I've used.
For a 8' x 8' x 20' container, your fan (after accounting for the resistance of all the particle filters and exhaust air cleaners would need to pull 1600 cubic feet per minute)

The link also gives an example for a down draft design and cautions that
"the ventilation rate shall be able to maintain the concentration of flammable vapors in the exhaust below 25%."
and suggests that maintaining less than 25% may require additional air flow.


https://www.toolsusa.com/blog/how-much-air-flow-does-my-spray-paint-booth-require/
"The real issue with air flow in a spray paint booth is having adequate air. A 14’ wide x 9’ tall x 26’ long spray paint booth will exhaust at least 13,104 cubic feet of air per minute. Running this spray booth for twenty minutes requires 262,080 cubic feet of available air. This requires a building at least 17,472 sq ft with 15’ ceilings or 10,483 sq ft with 20’ ceilings. This issue of an undersized building can be addressed with booth design and/or an air make-up unit. "

bearing in mind this is written for North America where, during winter, pulling sub-zero outside air into a building is undesirable, but the principle still applies


In terms of filters, How to Calculate Spray Booth Air Flow (http://www.binks.com/resources/tip-of-the-week/how-do-you-calculate-spray-booth-airflow)

Proper airflow is not only necessary for the protection of the operator, but is necessary to achieve the desired finish quality. Flow that is too low will not draw the overspray to the filters. Much of the overspray will end up on the part as dry spray (rough finish). If the flow is too high, solvent tend to evaporate too quickly resulting in dry spray.
To calculate the amount of exhaust air needed for the booth, a simple calculation is used.
CFM = Booth Face Area in square feet multiplied by the required flow (typically 100 FPM)
For example, and 8 X 10 filter bank (80 square feet) would require an exhaust of 8000 CFM (100 X 80) to achieve the required 100 FPM velocity.


and although not an NZ or Australian standard, the information here NFPA Ventilation Standards - Paint Booth Technologies - Industrial & Automotive Paint Booths (http://www.paintboothtechnologies.com/resources/nfpa-ventilation-standards/) should be a useful guide.

[Albert]

Hi Albert

looking at your other posts, your "shed in the garage" is really a small scale industrial set-up -- though we both know it's just a well funded "hobby".
So I can't see you settling for anything less than small scale industrial for your spray finishing.

However, you should seriously look at contracting a professional to do your finishing. While the rate might appear exorbitant, in reality it should represent a fraction of the value add from applying a spray finish. If the professional would charge you $200 to apply a finish, you should be looking to cost your own finishing at a similar (if not higher) rate, which at a cost of $200 per item should represent a $400 (or more) increase in the piece's value. If the client is not prepared to stump up for the additional value (i.e. cost to them) then you have to ask why you would invest in a booth.
If the client is only prepared to pay $100 more for a finish that costs $200 then accepting only $100 means that you are going backwards.

Thanks Ian!
Sometimes I am not even sure I needed it or I wanted it lol

I think having my own booth so I can hire someone as a contractor to do the painting for me. I can pay a painter an hourly rate rather than pay him $200 for a piece.

[Albert]

I've googled a bit about spray finishing ...


....and although not an NZ or Australian standard, the information here NFPA Ventilation Standards - Paint Booth Technologies - Industrial & Automotive Paint Booths (http://www.paintboothtechnologies.com/resources/nfpa-ventilation-standards/) should be a useful guide.

Thanks again Ian!

over the weekend I have found a professional spray painter who will be helping me to set up my booth.

he is dismantling his booth (retiring) and I have bought some of the stuff I need from him (I have actually bought a 800mm diameter Hison extractor fan from him already), the flow rate of the fan is about 17000m3/hr at 15mm of water pressure, or 20400 m3/hr at 5mm of water pressure, this is high for the size of my containter booth(usable volume of around 8m3) but I will have a VSD on the fan so I can adjust the speed of the fan. Its better to have a bigger motor than too small. here is the fan curve of the Hison fan, mine is 28 deg pitch.

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my booth will be at the back of the property rather than on the drive way.

Sitting on the driveway is asking for neighbours attention. having it at the back of the property meaning I will need to put money down on the compressed airline and a power supply. but it will be out of sight.

Will upload photo as I go.

[ian]

I think having my own booth so I can hire someone as a contractor to do the painting for me. I can pay a painter an hourly rate rather than pay him $200 for a piece.a word of caution

I don't know about Auckland, but in Sydney hiring a contractor to work in a spay booth you own (or rented) would mean that you ceased to be a "well funded hobbyist" and became a "home based business".
In the areas of Sydney that I am familiar with, your existing scale is possibly beyond what is would be tolerated (or even permitted) as a home based business not to mention the wall of workplace safety and compliance issues that would tower over you as soon as you became an "employer"


Personally I think your better option is to contract an external provider to do the finishing.
Issues associated with speed and volume of air flow through the booth, filter performance, gun selection and finish preparation, spray pattern, clean-up, work health and safety, etc are all yours if you own the booth and just contract the labour to spray the finish.

[Albert]

a word of caution

I don't know about Auckland, but in Sydney hiring a contractor to work in a spay booth you own (or rented) would mean that you ceased to be a "well funded hobbyist" and became a "home based business"..... etc are all yours if you own the booth and just contract the labour to spray the finish.

yes I know if I start to employ people I become "Person Conducting Business Under Taking" with the new health and safety legislation in NZ... if I provide proper health and safety gear and training then I am all good. its just matter of time before I have to do this properly.

its a long way before I produce enough items require someone else to do the spray painting anyway. the booth will be modular so if I ever want to sell my house to a permanent location, I will just put it on a truck and leave.

At the moment I am on the border of permitting - local authority's bottom line is that I am not doing this as my full time job and the impact on the environment is within reasonable tolerance. will have to put a lot of filter on the spray booth to ensure no smell/fume is seen.

[ian]

... if I provide proper health and safety gear and training then I am all good. what might trip you up under that scenario is showing that you are "qualified" to provide the training and competency assessment. Doing so might require that you hold a fistful of formal qualifications