Extractor fan for spray booth Heeeelp?

[seaco]

Hi All

Today we have been mostly making this small spray booth with an 8" extraction fan, we tried the fan before fitting and it worked trouble is now it's finished and run for longer the fan starts slowing down to a crawl so we think it's kn*ckered...

now I've read up on fans it seems that we need something that is explosion proof eeerm, yep makes sense does anyone have any ideas what we may be able to use in place of this fan I have looked and can only find an explosion proof fan at WAIT FOR IT £652 yep £652... :roll:

There must be a cheaper way, gentleman over to you?... :wink:

My mate showing how pi**ed off we both are... and yes he is trying to shoot it with a drill???

Closed up...

 

[bluezephyr]

I dont know much about explosion proof fans, But if a mist of paint is running past electrics it cant be too good for it. That fan wont really pull alot through it and without a filter it will get caked up in no time.

The chaps in the unit next door to me use a machine mart cheap extractor with ducting and welding hoods to get rid of welding fumes, This might be the way to go, Good suction and the mist/fumes dont go over the electric bits, Just over the vanes.

 

[Chems]

In this the guy just puts a cardboard box with holes in over the fan to stop the main spray getting into the fan.

 

[seaco]

Hi Chaps

Sorry forgot to say we will be putting a filter of some sort over the fan but this of course doesn't stop the fumes?

 

[Digit]

Use a centrifugal fan with the motor outside the duct.

Roy.

 

[seaco]

Hi Roy

Just had a look and there's so many versions could you send a link of the type you mean please?

 

[CHJ]

Seaco, as roy says you need a fan unit with a metal impellor housed in its own casing with the motor outside the casing, therefore not in contact with the fumes.

Look at cheap chip extractors or cyclone centrifugal fans for construction method.

 

[Digit]

They are snail shaped Lee, size depends on how much air you want to move. If the fan you are using moved enough air an old fashioned car heater blower or similar would do it.
Quite often booths are/were lined with thin polythene that was discarded when heavily coated so extraction was/is limited to preventing blow back at the operator. A curtain will also do that.
But as I said, how much air do you want to move?

Roy.

 

[seaco]

Well Roy, it needs to keep the area shown clear I have no idea what I'd need to do that?

Also I haven't found prices yet but proper ones look as though they are going to be pretty expensive, I can't tell from pics I've seen were the fan would be sited the fan in our picture vents through a 7.5" concrete wall to the outside?

 

[Digit]

Did the existing fan keep the finish from blowing back? If so that is the fan size you require.
If you go too large and suspend a panel in the booth it will start to swing back and forth, not good when spraying.
Take a look at commercial booths for fan size.
If you have a small chip collector try that out.

Roy.

 

[mailee]

I might be teaching you to suck eggs here Lee but have you considered a pressurised booth? In a full size spray booth as we use at work there is a slight positive pressure to help keep out dust and contaminants from the booth. The incoming air is at a higher pressure and thus no extractor fan is required as such. Air exiting the booth goes through a smaller vent and the incoming air is forced through a filter. In a small set up it may work by using a large fan pushing the air in and a smaller vent to let out the air. Just a thought to ponder on?

 

[seaco]

Did the existing fan keep the finish from blowing back? If so that is the fan size you require.
If you go too large and suspend a panel in the booth it will start to swing back and forth, not good when spraying.
Take a look at commercial booths for fan size.
If you have a small chip collector try that out.

Roy.

Roy unfortunately we didn't get to try the fan shown as I said it only ran a short time before slowing to a crawl, I will have to look at other booths to see but I'm still unsure where the Centrifugal fans fit is it inside the shop or out?

Wouldn't a chip collector soon clog up?

I might be teaching you to suck eggs here Lee but have you considered a pressurised booth? In a full size spray booth as we use at work there is a slight positive pressure to help keep out dust and contaminants from the booth. The incoming air is at a higher pressure and thus no extractor fan is required as such. Air exiting the booth goes through a smaller vent and the incoming air is forced through a filter. In a small set up it may work by using a large fan pushing the air in and a smaller vent to let out the air. Just a thought to ponder on?

Mailee no sucking eggs here mate I'm new to making these booths although I can and have sprayed a fair bit but the company I did it for was very Heath Robinson!

We need to keep the costs down as much as possible, Roys idea of the Centrifugal fan seems good but I'm unsure how it would fit into the setup we have, does your idea mean we would have to almost completely enclose ourselves in the booth some way to produce the positive pressure if so this would be difficult to impossible due to available space?

 

[Racers]

Hi,

You need to strip the fan down and clean and re-oil the bearings its probably an induction motor with a couple of oil impregnated bearings at each end, if you can't strip it down might just be able to get a drop of oil on them.
I do this with my bathroom extractor and it goes twice as fast afterwards.
Pete

 

[9fingers]

Going back to the original question, if your fan has an induction motor then there is no sourch of ignition. keep all the switching well away from paint fumes in a sealed box and you should be OK. In the unlikely event of the fan motor coils burning out there could be a spark but this is pretty unlikely.

Make sure there is not an over temperature cut out swithc burried in the motor somewhere - that could spark.

There is some hope for your vent-axia but a snail blower with enclosed motor would be better.

Good Luck

Bob

 

[Inspector]

Here are a couple booths you might get some ideas from. These use centrifugal fans mentioned earlier.

http://www.grizzly.com/products/g0532

http://www.grizzly.com/products/g0533

If it were me I would put one of those axial flow barn fans with the self closing louvers in a window with some filters in front and only use water based finishes. Like the one below only bigger.

http://www.princessauto.com/_osn.cfm?CT ... TING%20FAN

 

[Digit]

If the fan is placed some distance from the the booth any paint will tend to settle in the ducting rather than on the blades, so I would use cheap tumble dryer hose and throw it away went loaded with paint. That way you can position the extractor away from the booth.

Roy.

 

[seaco]

Going back to the original question, if your fan has an induction motor then there is no sourch of ignition. keep all the switching well away from paint fumes in a sealed box and you should be OK. In the unlikely event of the fan motor coils burning out there could be a spark but this is pretty unlikely.

Make sure there is not an over temperature cut out swithc burried in the motor somewhere - that could spark.

There is some hope for your vent-axia but a snail blower with enclosed motor would be better.

Good Luck

Bob

Hi Bob

I am completely green when it comes to motors how would I tell if it's an induction motor and as for a over temperature cut out switch, I wouldn't know one of those if I saw one?

Here are a couple booths you might get some ideas from. These use centrifugal fans mentioned earlier.

http://www.grizzly.com/products/g0532

http://www.grizzly.com/products/g0533

If it were me I would put one of those axial flow barn fans with the self closing louvers in a window with some filters in front and only use water based finishes. Like the one below only bigger.

http://www.princessauto.com/_osn.cfm?CT ... TING%20FAN

Inspector

Those look excellent bits of kit but are going to be well out of our price range!

 

[seaco]

If the fan is placed some distance from the the booth any paint will tend to settle in the ducting rather than on the blades, so I would use cheap tumble dryer hose and throw it away went loaded with paint. That way you can position the extractor away from the booth.

Roy.

Hi Roy

Thanks for that info I'm just a bit worried now about giving myself instant sunburn using the wrong type op fan?

 

[Jake]

What are you going to be spraying? Solvent, or just water-based?

 

[seaco]

What are you going to be spraying? Solvent, or just water-based?

Hi Jake

It will be both but water based until we can get a proper fan I think!