i want to sandblast some wrought iron patio furniture with my new harbor freight sandblaster, but i can't find a respirator suited for sandblasting. all the local hardware stores' respirators say NO SANDBLASTING. even called a sandblasting supply house but the only respirator they have is some type of injected air system that costs almost $400!
i'll be doing the blasting outdoors, if that makes any difference.
Using sand (silica) is illegal where I live, particles can be too small for a respirator to safely protect you, hence the air supplied unit. Also the risk for a supplier of respirators is that it may not protect you from the muck being blasted off, eg lead paint, epoxy, fibre glass.........
Special blast media is available I think made from milled iron ore slag?? but stand to be corrected. Does not break down into fine particles, but you still have the dust from the muck.
I use wet sandblasting which stops that whole dust issue, venturi on a high pressure washer sucks dry sand into the water stream, water and sand then do a better job than dry abrasive alone.
The big concern is breathing silica dust, which causes serious health problems. There are good respirators on the market that should filter the vast majority of it from the air you breath, but only an injected air system would eliminate it, as you've discovered. The positive pressure in the respirator prevents migration of outside atmosphere----but your air supply must be quite clean.
If you work with your back to the wind, and don't blast on a calm day, you're likely to get by fine with one of the respirators that have cartridges and felt filters, in spite of what they say. I'm sure the warnings are there to cover the manufacturer for liability reasons, letting them off the hook when their product is used *improperly*. Using one of the better quality respirators, not one of the little disposable models, unless you blasted continually, day in, day out, I don't think you'd be exposed to enough to be harmful, assuming you have good health now. Just make certain the respirator fits snugly on your face, and the filters are in place such that air can't get around them. One other thing. The abrasive bits bounce around quite a bit, so a face shield is a good idea. Blasting works a lot better in a cabinet, where nothing bounces back at you.
I assume you have a serious air supply. If you have a small horsepower compressor, you're not going to have enough air to do much blasting, anyway. You'll spend your time waiting for the compressor to refill. I can't think of anything more frustrating. If your compressor is less than a serious 5 horse model, you'll see what I'm talking about. Blasting is very demanding of the air supply.
I was thinking of making my own air supply. I already have a sandblasting hood made from combination canvas/rubber. I intend to use about 60 feet of garden hose with air supplied by an old squirrel cage furnace fan. I will have to build a plenum for the fan and hook up the hose with duct tape. Assuming that I get positive pressure to the hood, AND, wear a cartridge respirator underneath, I think I will be OK and save approx. $800. Any thoughts from others?
Personally I doubt a furnace fan will develop enough pressure to drive much air through 60 ft of garden hose. Fans are intended to move a lot of air at low pressure. I think you'd be better off feeding your mask from your compressor with a pressure regulator and filter.
Myself, I stick the item in my bead-blast cabinet, seal the door...
The whole reason they put that warning on the respirator package is to insulate themselves from the lawsuits. Or at least, to try. It's like the cardboard sun shades for your car windshield, with the lawyer mandated "Remove Before Driving Car" printed on them.
If this is a true DIY job, I'd use a full respirator with the right cartridges and pre-filters (not the cheaply molded dust mask type), and then have the wind at your back and use a hood or balaclava to make the dust work that much harder to get at the filters.
If you are paying someone else money to do this blasting work as an employee, you'd better follow all the safety rules and supply all the high-dollar safety equipment. Or it's guaranteed that someone will (according to their attorney) "develop a nasty cough" and try coming back and taking you to the cleaners later.
Nice idea, but you need a more powerful fan and a larger hose. Furnace blowers work fine when moving lots of air using big ducts, but they won't push against much more than 0.5 inch of water backpressure, and a garden hose won't flow very much at that pressure. You'll need to work against at least 5" WC backpressure.
For a remote air supply, think a small regenerative or ring blower or a vacuum-cleaner motor blower to get enough flow and pressure. Bypass cooled motor, so you aren't breathing in ozone and trash from the motor and brushes. And make sure the motor is getting enough cooling air, especially if you enclose it for noise - it might need a separate muffin fan and ventilation path.
You need something bigger than garden hose to get the proper airflow, they make 1-1/2" and 2" spiral-reinforced hoses that would work nicely. Search for 'transfer hose' or 'dry food hose', I would suggest a version with a static ground wire - go look around at McMaster pp195 196 197 for some ideas (MSCDirect is 'unavailable' as I write this.)
Or to do it on the cheap, go the local Borg (Home Depot/Lowe's) and get a new pool vacuum hose.
And box up your air supply system and put one of those respirator filters on the air input. Won't do you much good to have a remote air supply if that air is coming in contaminated...
Mungo's right about this feeling like a Darwin Candidacy issue. Garden hoses are usually marked "DO NOT DRINK FROM THIS HOSE". What makes you think you should breathe through it, respirator or not? Think back to when you last had a very small disturbance in your respiratory tract. Is ANYTHING worth doing something which might cause that feeling of drowning again?
Check Ebay for inexpensive "supplied air" systems; they're half what you think they cost. ($279.99 complete)
Are your health and your life worth that? ;)
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