Spray booth?

[dvddvd]

Currently I have a lined workshop/ shed in my garden which I want to make more spraying friendly.

I do have a 12 inch fan extracting to the outside but it's very noisy add the turbine noise from my qtech5 makes it a bit over powering for the neighbours!

So I've decided to do something about it.

First I'll divide the workshop into 2 areas, a clean spray only area.
Add a new fan and add intake filters to the new spray area

The questions I'd like to ask

What size fan do I need? I need it explosion proof

What size air intake Filters do indeed?

I also wanted to build a hush box in the non spray area for my qtech 5 turbine which will have some sort of ventilation
Anybody done this?

Thanks

 

[Ollie78]

Built mine using a squirrel cage type fan inside a big MDF box.
These fans are supposedly better in this type of operation.
I think it is a 750 watt motor and is pretty hefty. When you turn it on it sucks the door in against the seal.

I use spray booth media to filter it in 2 layers, outside is the coarse paint stop fibreglass then the fine one underneath. This is cheap in comparison to filters.
I hold it in place using frames with square wire mesh. The 150mm outlet from the fan is at the back of the box and goes out through a duct.

The one I made is a bit like this,
https://www.filtercareonline.co.uk/products/air-cube-your-portable-spray-booth
but made with MDF for about 300 quid

It will likely be pointless making a hush box as the fan is going to be pretty loud anyway.

 

[Sideways]

For DIY work, it shouldn't need to be explosion proof. Move lots of air, don't spray heavily and continuously and you should be able to stay below the explosive limit.
Any doubts about this, read up and do the maths. No one else is going to take responsibility for you.
Stay 3, 5, 10x below the limit.

I'd upgrade your fan too but a centrifugal, backward curved one not a squirrel cage. Squirrel cage move lots of air, make more pressure than a simple propeller type fan but but not a whole lot and they stall easily if you put too much filter in the way or it gets too dirty. You're going to filter the air in and out yes ? So the air comes in cleaned of dust and the overspray is caught instead of being blown through the fan and across the garden ?

How much air ? If it was a trade spray booth with most all of the back end of the booth being filter, you would aim to extract enough air to make an air flow of about 2 maybe 2.5 mph from the door to the filter wall at the back. This isn't fast. It just carries any spray in the atmosphere slowly but steadily away from you. If the back of your booth was 2m x 2.5m, that would need 8,000 m3/hr or an 18" diameter fan with about 1kW of power. I don't imagine you'll build anything anywhere near that big, but you probably need a fan a good deal bigger than you expect.

So then you work out if you can scale that down depending on the size of your projects. Those portable air scrubbers used for on site work with plaster dust etc are typically 1,000m3/hr or 2,000 for the bigger ones. I wouldn't want to go smaller personally.

HTH

 

[scholar]

Re soundproofing for the HVLP unit, a long time ago I saved this plan for a noisy workshop vac. The HVLP works on the same principle of air in/air out, so you may find this helpful.

Cheers

 

[niemeyjt]

Explosion proof fans - maybe for spirit-based finishes - but for water-based? Not sure.

What about a "pop-up" spray booth?

 

[meccarroll]

I would consider moving over from your noisy HVLP Qtech 5 to a compressor with a HVLP Spray gun because the noise difference is huge.

I have a couple of HVLP Turbines and they are both very noisy, this summer I was spraying a kitchen and ended up with a headache from the Turbine so switched to my compressor and purchased a HVLP spray gun to go with it and it's great.

The gun I purchased is the one below, it does not have a huge fan but it's enough for spraying kitchen doors etc.

You will need an on gun regulator to ensure you have the correct pressure at the gun so you obtain the efficiency of the HVLP spray gun.

My compressor is not huge at 2Hp but it's enough to run the above gun. I also have a devilbis FLG5 Complient spray gun and that's also very good with the compressor (not too much overspray) so long as you use an on gun regulator.

 

[dvddvd]

Its Nitrocellouse id be spraying

Explosion proof fans - maybe for spirit-based finishes - but for water-based? Not sure.

What about a "pop-up" spray booth?

 

[meccarroll]

Its Nitrocellouse id be spraying

I have sprayed Cellulose many times before mainly in the open, it's quite easy to spray in some respects. It is a volitile paint based on highly flammable solvents evaporating so I'd think if you are spraying in a confined space you would need to be careful none of your equipment or spray environment can trigger a flash point. Flicking a light switch can cause a small spark, Lighting can also trigger an ignition of the vapours.

 

[johnnyb]

Cellulose is really old fashioned. I knew it was available but last time I used it was 30 years ago! This was for finishing mahogany furniture using the pullover method. It's very thick and yellow. I've no idea what your finishing but pre cat is usually much much better and clearer.

 

[dvddvd]

Hi yes it's a pre cat version, it sprayed on lovely, very easier apart from the fumes!

 

[Limey Lurker]

Greeves Invacar spray shop had a waterfall at the back which took care of a lot of the overspray. Strangely, the Paint Shop Foreman was a registered blind person! Every month he would spray test pieces which were sent the Min of Health fer testing, where they measured the thickness of the paint layers, then scraped off the paint and weighed the scrapings, and finally, scraped off and weighed the phosphorised rust 'proofing'. I never heard of any failures.

 

[Katomi woodsmith]

For what it’s worth my 5 eights are
I would go for a sealed explosion proof extraction fan
Having seen flour explode and seen a fool use a wet vac to syphen petrol (he lived, car not so lucky) I stay on the side of caution/overkill

 

[dvddvd]

I found Vevor were selling explosion proof extractor fans, they look the same as the ones selling on ebay shipped from Germany.
I googled the make and model and one of the search results came from the UK government website

 

[dvddvd]

So maybe all explosion proof are not equal
.
It's strange that ebay still sell them even after a warning from the UK government are buisness above the law now?

 

[BillK]

It doesn't say that fan is banned or illegal to sell, just that they 'strongly recommend that owners stop using this product'.
ATEX is the gold standard, anything else needs personal judgement. Brushed fans are cheapest and best avoided for solvents, sealed brushless IP68 and such probably £250 upwards, ATEX £1k+. That's probably why people get drawn to suspiciously cheap Chinese fans like Vevor that promise to be explosion proof for not much more than a cheap brushed fan, despite them selling anything & everything from spatulas and bike racks to those fans.

fwiw from using my own booths I do think it's quite hard to reach the LEL with spraying alone, in any reasonably well-designed booth & extraction that is, but everyone has to decide what they need. A business with insurance, staff etc, would think nothing but ATEX would do. And fans are just one part of what should be done against fires.

 

[dvddvd]

Surely it's illegal to sell safety items that are not what they claim...years ago the trading standards would be kicking the doors down..its a free for all now.
When Amazon and the likes sell chinese lies goods and nobody bats an eyelid.

Last year I was buying a portable battery bank, I bought an unbranded 10000 ah version from Amazon it tested at 5000 ah.
An Anker (branded one) Was 10000ah tested at 10000ah

Amazon still sell the unbranded 10000ah ones?