air fed mask air supply requirement

[Matt@]

Just wondering whether anyone on here knows anything about air fed masks? I'm thinking of getting one but am struggling to understand about compressor requirements. I've read that a mask needs 7 CFM - this seems quite high? I'm looking at silent compressors and they seem to go from 1.7 CFM to around 3.5 CFM.

ideally I'd want to use a compressor like this
https://www.machinemart.co.uk/shop/prod ... mpressor-2

any advice welcome!

 

[CHJ]

Why would you want to compress large volumes of air just to subject it to extensive and expensive filtering and expand it again to feed a face mask in a wood working environment?

All you need is low pressure air volume that can be achieved with several brands of fully portable body mounted battery powered units.

 

[Matt@]

ok thanks. As you can see I dont know really much about these devices! How do the battery powered air fed masks work ie I presume the battery part is a pump? where does the clean air come from?

 

[Matt@]

just spoke with 3M its got to be air fed for DCM strippers as thats what I need it for.....

 

[n0legs]

The compressor you link to, with the specs mentioned, won't run an air fed mask.
The 7 cfm you have been quoted for the mask is probably right, certainly very close.
I have an older DeVilbiss mask at home. My compressors are producing about 12-15 cfm and if I use the mask with my smallest paint gun (approx 3-4 cfm demand) I just about get away with it. The compressors are running constantly.

The air needs to be clean and dry before it gets to the mask filters.
My DeVilbiss and their newer models have a belt mounted regulator worn by the operator. The regulator is preset for the air supply, so you are getting enough air at the right pressure. Inside the regulator there's a charcoal filter, this needs changing every couple of months, check the manufacturer.
The airline from the compressor has to be clean, on the inside, and in good condition. Ideally you should have one airline and keep it just for feeding the mask. Some airline systems have "oilers" installed to maintain the air tools, obviously the airline will get contaminated if used in this kind of system.
I have 3 stage filtration at home and it still isn't really good enough.
My BIL has a bodyshop, his compressor has a filter, then it feeds into a dedicated dryer unit, through another filter into the main airline. At the booth there is a set of 3 filters then a regulator and then finally the the belt regulator/filter.
The air is perfect, well it has to be, but if you get it wrong you can do yourself some real harm. Just remember you will be force feeding the air, and any contaminates in it, directly at you.

I had to look up DCM strippers. Not good, really not good. What I found said for professional use it's been withdrawn and they were aiming for a total ban.
Do you have to use them, isn't there an alternative?

 

[CHJ]

just spoke with 3M its got to be air fed for DCM strippers as thats what I need it for.....

I would strongly advise you to get specialist advice about any installation that is intended for use with such Chemicals.
When dealing with any installation using such substances a vital part of the design of air supply has to be the separation of extraction fumes from replacement air source.
Home cooked installations may meet your own perceived requirements but public liability might be a greater factor needing consideration.

European Ban

The EU ban comes through REACH, a European Union regulation concerning the Registration, Evaluation, Authorization & Restriction of Chemicals. REACH took effect June 1, 2007, replacing a number of European Directives and Regulations with a single system. REACH regulations apply to all EU member states.

The new ban makes a distinction between three types of use:

• Industrial use of paint strippers will be allowed only in “industrial installations” (facilities where paint stripping takes place), as long as certain safe working practices are followed.

• Professional use by workers will be banned outside industrial installations, unless individual countries make exceptions for “specifically trained professionals.”

• Consumer use by the general public, and supply to consumers, is banned.

The ban applies to DCM-based mixtures used for stripping paint, varnish or lacquer. Pure DCM (or mixtures containing it) sold and used for other purposes such as degreasing can continue to be sold and used (although not for stripping paint).

(above from one of many references to DCM use)

Also when dealing with any installation using such substances a vital part of the design has to be the separation of extraction fumes from the general public.

 

[Matt@]

thanks for the info re. air fed supply source, thats exactly the info I was after....

 

[lurker]

You should not be looking for advice of this nature on this forum.
Seek professional help otherwise someone is going to get seriously hurt.

 

[rafezetter]

Just to add something n0legs missed was that the high cfm rate of an airfed mask is to maintain positive pressure inside the mask, so if there are any airgaps around the seal, however tiny, the positive pressure fed from the airline pushes everything OUT, thus making it impossible for any contaminated air to enter the facemask via a seal breach.

DCM.... I have to concur seriously seriously not good stuff, I've sprayed for many years (not professionally though) and sprayed 2pack isocyanate paint in the past, but I would never consider using any DCM based product. Ever. As Lurker says, you should seek professional help regarding a spray set up, and do not consider skimping any corners under any circumstances; and if you cannot afford what they recommend, find another way to do whatever you are trying to do.

Sandblasting (a generic term not just sand - which is also bad without an airfed), beadblasting, bicarbonate & water (very gentle stripping & very good for keeping airborne particles to a minimum), all are significantly safer stripping methods, with plenty of places who can do it for less money than buying a whole setup for dealing with DCM, which I would imagine could easily run into the thousands.

 

[n0legs]

Just to add something n0legs missed was that the high cfm rate of an airfed mask is to maintain positive pressure inside the mask, so if there are any airgaps around the seal, however tiny, the positive pressure fed from the airline pushes everything OUT, thus making it impossible for any contaminated air to enter the facemask via a seal breach
.

Yes, very good point . I did neglect that =D>

 

[mailee]

For an air fed mask you will need a compressor that is capable of at least 15CFM free air! if you are also using a HVLP set up then it needs to be even higher. A compromise is to use two compressors one for the gun and one for the mask but this is not always practical. HTH. :wink: As for the DCM I have never heard of it but it sounds like you don't want to touch it with a bargepole. :wink:

 

[Matt@]

many thanks for all the feedback on the air fed question. The debate on DCM usage has been rumbling on for nearly 30 years and I have always been interested to hear peoples views on the subject during this time

heres an interesting one.....
http://www.ebay.co.uk/itm/Dichlorometha ... 3aa60d64e5

 

[clk230]

many thanks for all the feedback on the air fed question. The debate on DCM usage has been rumbling on for nearly 30 years and I have always been interested to hear peoples views on the subject during this time

heres an interesting one.....
http://www.ebay.co.uk/itm/Dichlorometha ... 3aa60d64e5

Just reported to Ebay as a hazardous material !!