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cutter
08-02-2003, 09:03 PM
Outside of specially designed compressors, is there any others ways to supply fresh air to a hood as used in home project sandblasting?
How about oilless air compressors?
Filters for air from your regular air compressor?
??

Thanks.......

wierdscience
08-02-2003, 11:03 PM
Ah,clean breathing air,I have a Clemco filter that cost moocho dinaro,it plugs in to a seperate air line from the compressor head,it has a oil coalesing filter that strips the oil from the air supply,and a .5 micron carbon filter to remove any impurites,and a high volume-low pressure regulator,this unit works extremely well but is expensive and bulky.

I later came up with a smaller unit that I built from parts obtained through McMaster-Carr,I purchased a oil coalesr,carcoal filter and cartrige holder,along with a high volume regulator and large id hose from them.My air supply hood requires 10-15psi and 12-20 cfm to operate efficiantly,remember not only do you breath through it but it is also under positive pressure,mine has clip on belt suspenders to hold the hood on.

Okay now for some details,the oil unit I got was rated for 150psi and 18cfm flow,the charcoal cartrige and filter housing rated for 18-20cfm and 125psi and the regulator is a 3/4"npt with an adjustable range of 6-100psi,The hose from the compressor is a breathing air rated 1/2"id hose rated for 120-150psi,the hose from the assembly is a 1"id poly spiral ribbed hose that is sold by the foot.

Now some words about safty,if your compressor is the oil bath piston type you will need to drain the crank case and tank and rinse both thouroghly and refill with oil specifically made for breathing air compressors,one old standby was a brand called mono-lec,it was a vegtable base if I remember right.The next concern is hose size and care,the longer the hose the more air friction ,the more air friction the less cfm can travel,I limit the length of my supply hose to 50'this has always worked good for me.Also keep your hose up off the floor and away from peoples walkway for obvious reasons.The other consideration is have some one look in on you regularly to make sure you are okay,even though your not deep sea diving some of the same dangers exist.

I switched to an oiless compressor for my breathing air and use it exclusively for that,you can also buy a carbon vane breathing air pump for a few hundred bucks if you really want to get into it,these are better for short duration jobs and there is only a small inline filter for the bulk of the carbon dust,carbon dust is inert in the human body in small amounts so not to much of a concern there.

What ever you decide remember that silicon sand dust causes imeadiate and permanet damage to the linings of the lungs,one thing I find true of all filtration systems is they provide dry air,so what I do is increase the amount of water I drink before and during so I don't get dehydrated so quick.

One more thing to consider is you might use a cabinet with a good negative pressure system for small stuff and take the big stuff to a pro,around here a monument company gets $30-40 bucks an hour,but they get a lot done in an hour,the setup from Clemco 10years ago was $850.00,the setup I built not counting the compressor was around $300.00 three years ago so there is some cost involved.

cutter
08-03-2003, 01:02 PM
wierdscience.......
Thanks very much for you reply......

I am aware of the dangers of the sand particles and appreciate your cautions..

Do you still use your self built filter with your airless compressor? I assume so......

Where would I find one of the carbon vanes pumps?McMaster-Carr?,??

I have a fairly decent, homebuilt cabinet but some things are just done better in the driveway......This is when I want the supplied air as well as maybe for spray painting in the future.......

All just for occasional use....Maybe a hour or so once a month for the blasting.....

Thanks again...

John

wierdscience
08-03-2003, 01:51 PM
The carbon vane pumps are usually on the same page as the air supplied hoods,look there,also Gast is the most common name brand you might check their website.
My homebuilt filter I still use although not with the oil coelesor(no need with the airless pump)

Michael Az
08-04-2003, 11:27 AM
Whatever you do, don't use the air from your shop air compressor. I almost did that some years ago and then found out the air tank could harbor some nasty bacteria that will also live in your lungs and you can't get rid of it. Auto painting body shops now pretty much use fresh air hoods/systems because most paints have some nasty chemicals that they cannot be breathing. I finally opted for a 4' X 4' cabinet.
Michael

Weston Bye
08-04-2003, 12:15 PM
I have sleep apnea and wear a pressurized mask on my nose when I sleep. This keeps my airways from collapsing and prevents snoring and interrupted breathing. The pump is a centrifugal blower, much like a hair dryer. Air is filtered and an internal sensor regulates the speed of the motor to regulate the output pressure. (0-10" water column, set at about 2" on my case)

I say all that to say this:
Why not a blower (inlet properly filtered) providing low pressure, relatively high volume air to a dust hood or mask? Provide just enough flow to provide a positive pressure differential. The hose would be somewhat more bulky, but need not be heavier.

Wes

Sprocket
08-04-2003, 03:42 PM
Wes- That is what they do on the HVLP paint machines that supply breathing air. They refer to it as a "turbine" but it's a blower of some sort. Gives clean low pressure air for painting and breathing

cutter
08-04-2003, 10:23 PM
Thanks for all of the replies.......PLEASE keep them coming!!

WES 1.......
I have kinda thought along the line of a blower for the air supplier.....Maybe even something like a squirrel cage blower like used in a central air system, then necked down to a hose feeding the helmet or respirator....

wierdscience
08-04-2003, 10:41 PM
Ya,you could use a blower,but a ring compressor or dust collector blower would be best,not a big one but one with at least 2.0 static pressure (measured with the outlet blocked)and you would need a larger hose for a supply tube,maybe a 1-1/4"id.

wierdscience
08-04-2003, 10:47 PM
Oh ya the filter that Clemco speced for the carbon canister is a .5 micron,so bacteria won't pass,and small amounts of voc's won't be a problem either so long as the pump intake is located away from a large amount of vapor.

winchman
08-05-2003, 12:42 PM
I use a mask that originally had two organic vapor filters on it. I removed the filters and capped one side. I made an adapter for the other side to connect to a flexible 1" low pressure hose. The hose runs to a swivel fitting on the ceiling. A 1" PVC pipe runs from the swivel to a small centrifugal fan outside my shop. There's a filter on the fan inlet to keep bugs out.

The pressure from the fan is just enough to keep the air constantly flowing through the exhale valves on the mask. I always have fresh air from outside the shop to breath when I need it.

It's been working great for over ten years.

Roger

[This message has been edited by winchman (edited 08-05-2003).]

Paul Gauthier
08-07-2003, 12:26 AM
One can purchase a battery operated fresh air hood, battery and motor attach to your belt. Hose from motor to hood.The air is filter before entering the hood. They use them all the time where I work when polishing dies and trimmers. Wish I could remember the manufacturer but with crs it's tough.

------------------
Paul G.

alumtuna
08-07-2003, 02:12 AM
I have been thinking of doing an air breathing system also. Here are my thoughts:

1) 3M has a half and full face respirator. They also sell an addapter that fits on the respirator for you to supply air into. Not sure but has a small filter also (while back since i checked)
2) I was thinking of using compressed air from SCUBA tanks and using a used regulator to reduce the pressure to what the adapter requires. Compressed air tanks (if you have them from SCUBA) are $100 to purchase with about $3-4 refill. They also last 1-2 hours run time. They are also free from power requirements and are towable (on you if you wish) different sizes available.
3) I would not use this set up much, additional safety measure for welding on surfaces i cant clean well enough, painting, sandblasting or just in case where i require additional safety measure.

What do you guys think of this approach?
Have any of you guys tryed this? Any lessons learned?

Thanks

wierdscience
08-07-2003, 09:24 PM
I used a similar system to work inside of a cement kiln conveyor house once,cemet dust real thick everywhere,We got it from the local welding shop,big cylinder like an o2 bottle with 3000psi and a regulator,it had a half face piece and a 60'hose,it also had a bell that would ring when it got low,as I remember it cost $40.00 a day rent for the setup plus air,and you could rent the cylinder for a year for $60.00 if you had your own mask and regulator,it wasn't a bad deal just a hassle because you always run out at the most inopertune times.
My niegbhor has something neat,he has an old shallow diving pump that floats in the middle of an inner tube,it has a small two cycle motor that drives a small two cylinder pump,he says it works good to about 25'of depth,looks very interesting.

cutter
08-07-2003, 10:20 PM
I'm kinda wondering now, after reading these replies, about using an electric leaf blower as the air supply source.....Placed away from the source of the contamination and piped to close to the user with 4" tubing and then necked down to 1" or so to the mask/hood......
Problems??

Weston Bye
08-08-2003, 02:12 PM
Cutter:
The leaf blower might be a little overkill - too much volume and pressure and probably noisy too. You might end up behaving like a bagpipe. A relief port would solve the volume and pressure problems, but seems a waste. You might consider a defroster blower from a junk car. This and a variable power supply would allow you to adjust the flow to an effective but comfortable level.

Wes

winchman
08-08-2003, 02:18 PM
An electric leaf blower is going to be way too much flow and pressure for a face mask.

The centrifugal fan I use has a 4" diameter blade with a 1/12 HP motor.

Roger

alumtuna
08-11-2003, 03:03 AM
Anyother thoughts on the SCUBA idea. For running out of air you could use a two tank manifold or have back up scuba tanks. The scuba that floats in the middle of the pool was priced around $800 or so. Too much in my book.

winchman
08-13-2003, 11:18 AM
How much do SCUBA tanks weigh? Their weight isn't much of a factor in the water, but it might be uncomfortable to carry one or more around for very long in the shop.

Maybe you could get something like a fireman's tank, regulator, and mask instead.

Roger

Joel
08-13-2003, 01:44 PM
You don't want to know what those firefighting air packs cost! They are called SCBA's. Same as SCUBA, but without the U (for underwater). The units aren't all that light, and only provide air for about 15-25 minutes.

joel_k
08-14-2003, 02:06 AM
I used to use a small, oilless compressor pump that was made to supply clean air directly to a paint spray gun. It had no tank and supplied just enough air to pressurize the hood and supply breathing air, probably about 5 - 10 PSI on a 25' 3/8" hose. It worked pretty good and the air quality seemed good. It was supplied as a unit with a spray gun and a small short hose. If I get time, when I get home this weekend, I can try and look up a name or brand.

chestef
08-21-2003, 03:34 PM
A good friend of mine paints antique cars using compressed air through a comercial filter that removes the oil and contaminants. Wwhen I inquired where to buy such a rig he told me about a guy who attached pool filter hose to an ordinary 3M type cartridge mask and a hair dryer to supply the air. Of course he disabled the heating elements in the hair dryer, placed a hook to hang it up outside of the shop, and made a pipe that passed through the wall to attach the hose. He gets outside air, has freedom to move around, and if the air supply fails he still has one of the 2 filter cartridges attached to filter the air while he exits the space.

I have considered the same but PVC pipe with nipples at different locations in the shop and a manageable length of hose to reach form one of them to where I am working. This cuts down on tripping and hanging up on things.

------------------
Contemporary Blacksmith with building projects from foundry to an S/C Cobra

Dusty
08-06-2004, 01:04 PM
Sorry I posted the same questions on two forums. Didn't realize the first actually came through.

What type of tubing works well for 50 - 100 ft? I looked at replacement/extension hoses for professional setups (out of the price range!) Do they need to be cleaned?

[This message has been edited by Dusty (edited 08-06-2004).]

HTRN
08-08-2004, 10:07 PM
check with racing suppliers as many new helmets have a fresh air intake. the small blowers for these are pretty reasonable, but you will have to rig something for power - since they're meant for cars they're meant 12V. Try a place called RacerWholesale - I remember them selling the blowers.

HTRN

Your Old Dog
01-07-2005, 09:16 AM
Why not a blower (inlet properly filtered) providing low pressure, relatively high volume air to a dust hood or mask? Provide just enough flow to provide a positive pressure differential. The hose would be somewhat more bulky, but need not be heavier.

Just a heads up from a fellow "hose head" (apnea patient) Becareful with anything that may not allow you to exhale properly. That's the danger in setting a cpap machine for apnea patients too high.

I bought a cabinet and still use a mask. My Pa had silicocous (sp) from an old job as a sand mold chipper in a steelmill. It's a tough way to go out.....

Ray....