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anyone used one of these ?

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anyone used one of these ?

Postby Craig Salisbury » 13 Jan 2021, 08:12

https://powerstarelectricals.co.uk/atex ... -852-p.asp

I tried a previous suggestion of using a bathroom fan for extraction..it helped, but wasn't really ideal, The one linked seems to be the cheapest that will be ok for pre-cats etc.

Im thinking 12" should be enough for a small makeshift booth?

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Re: anyone used one of these ?

Postby Mike G » 13 Jan 2021, 09:17

Blimey, Craig, are you going into manufacturing/ production? That's way over the top for a home workshop spray set up. I used something similar in a window when grinding old plaster off the wall in my house a few years ago, and it just about sucked the plaster off the wall for me!
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Re: anyone used one of these ?

Postby Craig Salisbury » 13 Jan 2021, 09:25

hahaha I was spraying some photo frames with precat a few months ago and it took a week to get rid of the smell. unfortunately you need to use an atex rated fan for solvent based coatings as they have a habit of causing booms. this is the cheapest i could find without having to put a giant hole in a wall

I'm sure there will be a lot of people that just use normal fans, but i'm not really willing to take a risk and would prefer the piece of mind of knowing my garage isn't going to explode.

I also should be making things instead of buying things.....
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Re: anyone used one of these ?

Postby 9fingers » 13 Jan 2021, 09:56

A standard capacitor run motor* switched with a solid state relay will be fully explosion proof and cost nothing like the one you link to.
Bob

* this is a common type used on fans as fans have low torque needs for start up.
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Re: anyone used one of these ?

Postby Craig Salisbury » 13 Jan 2021, 10:02

9fingers wrote:A standard capacitor run motor* switched with a solid state relay will be fully explosion proof and cost nothing like the one you link to.
Bob

* this is a common type used on fans as fans have low torque needs for start up.

would you happen to have a link to something I can buy? it needs to be portable due to the makeshift-ness of it all (im not even sure that's a word) it will also need to have a decent diameter so i can throw a filter in front of it.

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Re: anyone used one of these ?

Postby 9fingers » 13 Jan 2021, 10:13

Sorry no link but I’d be looking on eBay, aldidl offers etc for a basic fan and modifying the switching yourself.
The current aldi one has a dc motor which might be brushless which would be ok but NOT if it is a brushed motor.
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Re: anyone used one of these ?

Postby Craig Salisbury » 13 Jan 2021, 14:04

Alas i feel my ebay skills are not up to par, I have been looking for one of these for quite some time hoping for a used bargain. I can get one that fits in a wall but that really isn't an option although half the price.
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Re: anyone used one of these ?

Postby 9fingers » 13 Jan 2021, 14:19

Craig Salisbury wrote:Alas i feel my ebay skills are not up to par, I have been looking for one of these for quite some time hoping for a used bargain. I can get one that fits in a wall but that really isn't an option although half the price.


Surely you can come up with a stand/box etc for a wall one. t'aint rocket science?

As for ebay, set up a search with afew key words and you can get a daily email listing likely candidates, if you are not seeing what you want then just adjust the search words.

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Re: anyone used one of these ?

Postby Craig Salisbury » 13 Jan 2021, 14:24

9fingers wrote:
Craig Salisbury wrote:Alas i feel my ebay skills are not up to par, I have been looking for one of these for quite some time hoping for a used bargain. I can get one that fits in a wall but that really isn't an option although half the price.


Surely you can come up with a stand/box etc for a wall one. t'aint rocket science?

As for ebay, set up a search with afew key words and you can get a daily email listing likely candidates, if you are not seeing what you want then just adjust the search words.

Bob


goddammit bob you pushed me. i will get orf my arris buy the cheaper one and build a box for it....on wheels no less.

I really need to stop being lazy.
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Re: anyone used one of these ?

Postby 9fingers » 13 Jan 2021, 14:28

Craig Salisbury wrote:
9fingers wrote:
Craig Salisbury wrote:Alas i feel my ebay skills are not up to par, I have been looking for one of these for quite some time hoping for a used bargain. I can get one that fits in a wall but that really isn't an option although half the price.


Surely you can come up with a stand/box etc for a wall one. t'aint rocket science?

As for ebay, set up a search with afew key words and you can get a daily email listing likely candidates, if you are not seeing what you want then just adjust the search words.

Bob


goddammit bob you pushed me. i will get orf my arris buy the cheaper one and build a box for it....on wheels no less.

I really need to stop being lazy.


I'm not going to agree/disagree about the lazy but happy to know that a bit of lateral thinking has goaded you into action. I find it so much more satisfying stringing together some used bits and bobs into a custom solution as well as it being less stressful on the wallet. Don't forget to write it up to stimulate others!

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Re: anyone used one of these ?

Postby Craig Salisbury » 13 Jan 2021, 14:34

there I was all trigger happy before realising the wall mounted is just over 1/4 the power of the other one. i think im still going to look at a box making solution, at least then it can sit lying in wait against a wall until required potentially taking up less valuable space.
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Re: anyone used one of these ?

Postby novocaine » 13 Jan 2021, 14:56

I have to ask, what is it Ex rated to? no where does it give you what it's protected against. is it cat II or Cat III rated? what temperature class is it designed for? can I bung hydrogen through it and not worry? or is it only for methane?

don't want to dig in to this one to much but in short, you don't need that, you need want low level input (air being pushed in to the space) and high level output (non driven) with a filter on the input to stop contamination and a filter on the out to stop pollution.

this way you can use a lower category drive, as your zone 1 will extend to the boundary of a small spray booth and not beyond it. if you are going to force evacuated the space then you need to make sure the flammable mixtures is below LFL before it hits the fan, so big inlets are a must.

the actual zone from a spray gun that's running correctly is less than 1m from the tip in a cone shape, if your spray area is well ventilated the LFL shouldn't be reached beyond this.

these small spray booths that are popping up for things like guitars with drawn air ventilation have to meet cat II.

I'm stopping before I type a whole EPD. basically, have a think about why you need this and if there's a better option.
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Re: anyone used one of these ?

Postby novocaine » 13 Jan 2021, 14:57

9fingers wrote:A standard capacitor run motor* switched with a solid state relay will be fully explosion proof and cost nothing like the one you link to.
Bob

* this is a common type used on fans as fans have low torque needs for start up.


no it wont. but that's another discussion for another day revolving around what explosion proof means.
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Re: anyone used one of these ?

Postby Craig Salisbury » 13 Jan 2021, 15:04

novocaine wrote:I have to ask, what is it Ex rated to? no where does it give you what it's protected against. is it cat II or Cat III rated? what temperature class is it designed for? can I bung hydrogen through it and not worry? or is it only for methane?

don't want to dig in to this one to much but in short, you don't need that, you need want low level input (air being pushed in to the space) and high level output (non driven) with a filter on the input to stop contamination and a filter on the out to stop pollution.

this way you can use a lower category drive, as your zone 1 will extend to the boundary of a small spray booth and not beyond it. if you are going to force evacuated the space then you need to make sure the flammable mixtures is below LFL before it hits the fan, so big inlets are a must.

the actual zone from a spray gun that's running correctly is less than 1m from the tip in a cone shape, if your spray area is well ventilated the LFL shouldn't be reached beyond this.

these small spray booths that are popping up for things like guitars with drawn air ventilation have to meet cat II.

I'm stopping before I type a whole EPD. basically, have a think about why you need this and if there's a better option.


ok, so I know this is not ideal conditions, it's also a fairly infrequent occurrence, but the end goal is to be able to spray lets say a small unit or coffee table sized object in a 2.5m x 2.5m temporary area of a garage using pre-cat lacquer without it blowing up or smelling like lacquer for a week. temporary area meaning cordoned off with either poly backed floor to ceiling drop cloths or cellotex style board.
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Re: anyone used one of these ?

Postby novocaine » 13 Jan 2021, 15:29

The smell is from overspray gassing off, this won't fix that (if it did you'd have no finish on the item either).

easiest way to fix that is to sheet everything including floor and ceiling, spray then chuck the sheeting out straight away.

let me have a think about this as I don't want to give you incorrect advice and I've not done a DSEAR assessment for a small spray booth for years (did do one for a very very very large one in last 2 years though:) )


normally though if you can keep the flammable atmosphere below 25% of the LFL (which is 3% for ethanol the largest constituent in fiddes pre cat) then it's a zone 2 which makes Ex rating of equipment much easier and I'd follow the same line as 9fingers. that means good ventilation (something like 10-15 air changes per hour i'd have thought but I'd need to run the calculations) I'd still go with force inlet to keep the fan out of the zone.
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Re: anyone used one of these ?

Postby Craig Salisbury » 13 Jan 2021, 15:43

novocaine wrote:The smell is from overspray gassing off, this won't fix that (if it did you'd have no finish on the item either).

easiest way to fix that is to sheet everything including floor and ceiling, spray then chuck the sheeting out straight away.

let me have a think about this as I don't want to give you incorrect advice and I've not done a DSEAR assessment for a small spray booth for years (did do one for a very very very large one in last 2 years though:) )


normally though if you can keep the flammable atmosphere below 25% of the LFL (which is 3% for ethanol the largest constituent in fiddes pre cat) then it's a zone 2 which makes Ex rating of equipment much easier and I'd follow the same line as 9fingers. that means good ventilation (something like 10-15 air changes per hour i'd have thought but I'd need to run the calculations) I'd still go with force inlet to keep the fan out of the zone.



thanking you, its very much a hobbyist affair, id just rather not go out in flames just yet. :) im also thinking the use of the word "booth" sounds far too professional for my meager endeavour :)
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Re: anyone used one of these ?

Postby Craig Salisbury » 14 Jan 2021, 08:30

@novocaine

I have been doing a bit more research and i'm not sure if this is correct or not, forgive the layman's terms as this is clearly not my wheelhouse.

Option 1:
forced air in or positive pressure?
install a fan in the ceiling with a filter pushing air into the spray area
seal the garage side door (when open) with cellotex/kingspan with cutouts for 2 large filters (or make a frame with one big filter)

this should remove the requirement for an explosion proof fan? also i'm not sure how affective this would be if there's no active exhaust fan

Option 2:
negative air pressure?
Install a decent sized vent in the ceiling with filters
seal the garage side door (when open) with cellotex/kingspan with cutout for a filter, backed the other side with a 12" explosion proof fan

do either of these seem viable?


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Re: anyone used one of these ?

Postby novocaine » 14 Jan 2021, 09:18

I think so. :)

but saying explosion proof doesn't mean anything I'm afraid. you probably want a cat IIc rated motor and fan, but given the size of the area you may need to go up to a cat I. :)
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Re: anyone used one of these ?

Postby Craig Salisbury » 14 Jan 2021, 09:25

that all sounds very expensive :)
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Re: anyone used one of these ?

Postby novocaine » 14 Jan 2021, 09:33

cat II would cheaper than a Cat I. :)

this gives you a bit more information as what means what. not the one I usefully use but still useful.

http://www.schischek.co.uk/explosion-pr ... pment.html
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Re: anyone used one of these ?

Postby Craig Salisbury » 14 Jan 2021, 12:53

so if i go the more pricey route, the fan from the initial link they also sell through amazon. and they have a picture of the important label

Screenshot 2021-01-14 at 11.45.13.png
(588.15 KiB)


I assume its missing some digits
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Re: anyone used one of these ?

Postby novocaine » 14 Jan 2021, 13:03

so that's rated for a zone 1 (somewhere that you could get a flammable atmosphere frequently) but IIB T4 means it is't rated for ethanol which would be IIA T2. so it isn't really rated for what you want to do. :cry:
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Re: anyone used one of these ?

Postby Craig Salisbury » 14 Jan 2021, 13:05

Thanks for checking sir.....bugger, its back to the search then :cry:
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Re: anyone used one of these ?

Postby Craig Salisbury » 14 Jan 2021, 13:57

looks like it really isnt possible to get hold of something under 900 ish + switchgear etc. and thats too far out of my budget.

sadly it looks like im going to need a plan B.....which is probably not being able to spray pre-cat :cry:
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Re: anyone used one of these ?

Postby novocaine » 14 Jan 2021, 14:02

if you are a company, then afraid so.
if you are a home gamer, sheet up, where a decent air fed mask, spray then discard the sheeting. no forced ventilation.

or airless spray system, no overspray so less smell.
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