Yesterday, in response to my Coilhose Redi-Burst pocket air blow gun post, HangFire said: a missed opportunity to describe just what “OSHA Compliant” means in an air gun.
Yikes, I’d been avoiding this discussion for a while! I managed to dig up OSHA regulation standard 1910.242(b), which says:
Advertisement
Compressed air used for cleaning. Compressed air shall not be used for cleaning purposes except where reduced to less than 30 p.s.i. and then only with effective chip guarding and personal protective equipment.
That’s more or less what I heard before, that the outlets of compressed air blow guns must be reduced below a certain pressure (30 PSI) for safety purposes.
Why? Directive STD 01-13-001 answers that:
This requirement is necessary in order to prevent a back pressure buildup in case the nozzle is obstructed or dead ended.
OSHA provides 2 acceptable methods (PDF) in which tools can be compliant with their regulation. The first involves an air pressure reducer that is placed before an air blower nozzle, usually in the air line between compressor and air blower, and the second involves a nozzle with built-in pressure reducer or relief device that reduces the air pressure in case the nozzle is dead ended (blocked).
In the same document, further explanation of the standard is offered:
Advertisement
The intent of the regulation is to allow for proper cleaning operations and to prevent chips and other waste materials from being blown into eyes or skin of the workers which may cause injuries. The design of the orifice and the velocity of the air passing out of the orifice or nozzle shall be such that it will not cause the waste material being cleaned away to be blown into the eyes or skin. Any relief vents or ports shall not be a hazard to the operator.
In another comment to the Coilhose Redi-Burst post, Brett explained OSHA compliance in a way I’ve heard it discussed before, that the reduced pressure is to prevent skin and blood vessel infiltration should an air blow gun be aimed at someone’s body.
In an Exair explanation of OSHA regulations, it describes things a little better.
Looking at product description of the OTC blow gun that’s shown above, it says it’s designed for an operation pressure of 50 to 235 PSI and that when inlet pressure is 90 PSI, the venting design prevents pressure exceeding 30 PSI if tip becomes blocked. This wasn’t crystal clear to me until I looked at Exair’s explanation.
I should point out that OTC and Exair are not related companies, but the OTC had a related product description and Exair has an informative OSHA discussion page.
Going by the Exair explanation, an air blower or nozzle with relief or reduction valve ensures that, if it’s held against your skin, the full velocity and force of the compressed air won’t be forced into your body. The outlet pressure should not exceed 30 PSI if the air blow gun or nozzle is properly designed to be OSHA compliant.
Okay, so it’s starting to get clearer for me. Some air blow guns, such as this Coilhose model, require that Line pressure must be regulated to 30 PSI or less for rubber tip to be OSHA compliant. Those satisfy OSHA’s first acceptable compliance method. Others have built-in or attachable safety tips that satisfy OSHA’s second acceptable compliance method.
If your air gun doesn’t have a built-in pressure relief, you can buy a safety tip, such as this Guardair attachment via Grainger. I don’t recall seeing any safety nozzle tips that are female threaded to accept additional nozzle attachments.
There is also a great discussion at manufacturing.net, where they interviewed Guardair’s director of engineering. Towards the bottom of the article, there’s an explanation of how these types of safety nozzle tips, with side holes that redirect air in case the front of the tip is dead-ended or blocked, can actually improve air gun performance. They say that the Venturi nozzle design can increase the volume of air exiting the nozzle to boost available thrust by up to 250%.
Oops, this completely slipped my attention, but it makes perfect sense. Thanks to Bernoulli’s principle and the Venturi effect, there will be a pressure drop in the nozzle due to the movement of the high velocity air, causing more air to be drawn into their airflow from the holes on the side. Thus, you will have a greater volume of air passing through the front of the safety air blower nozzle tip, compared to volume or air that enters the inlet of the nozzle tip from your compressor.
Anyway, I think I’ve got a good understanding of OSHA’s air gun safety regulations now. There are also standards that regulate how loud an air gun can be, but maybe that’ll be a discussion for another time.
Please don’t take any of this as safety advice, because it’s not. Remember, I’m just trying to understand the standard ands regulations.
How’s your understanding of this stuff? If you have added insight, please share it in a comment!
Drew M
I’ve always heard that using a blowgun on yourself, you can drive an air bubble into a vein and cause an embolism. I’m not sure I believe it but that’s what I’ve always heard in training.
I wonder about the engineering decision for the 30psi limit and why shops aren’t required to have dedicated fixed 30psi regulated lines for blowguns.
Mark S.
That’s an overblown (pardon the pun) hype (meaning the air embolism). It would take about 500cc of air to create an actual air embolism large enough to damage the pulmonary vasculature and cause the heart to be starved of oxygen. Now if you were injecting it into the brain stem, different story (only about 30cc of air needed).
Mike
While I agree the threat is somewhat blown out of proportion, your numbers are far off. The volumes you are describing would cause immediate hemorraging throughout the body, not to mention hypertensive crisis, from the enormous increase in blood pressure and vascular volume.
Did you mess up a mL to cc conversion from a Wikipedia article?
Logan
Not to burst your bubble Mike (pun intended), but a mL and a cc are the same…
Mike
Yep, you are exactly right, but there’s a reason I asked the question I did. It’s not too hard to find out why I asked it specifically.
Pat
I’ve got a really cheap air accessory set that includes one of those safety tips that has female threads inside of it. In fact, it has a slightly larger diameter thread than the gun, as do all the other bits in the kit so you have to use the safety tip in order to use any of the other bits… The only problem is that the entire inside of the safety tip is threaded and you have to screw the additional bits all the way in which completely seals off the vent holes!
The part about the venturi effect is pretty interesting though. I have been putting small pieces of tape over the vents (don’t tell OSHA!) thinking that I would get more scour power for dislodging trash.
fred
There is also an OSHA noise level directive for blow guns. I believe that it is section 1910.95. One of the things we liked about the brand we bought most often (Milton) was that they came with a UL label certifying OSHA compliance. I imagine that other reputable brands are also compliant as well.
BTW – paint spray equipment also deserves careful attention and proper training to avoid hazards associated with injection of paint into bodily tissue.
Jeremy
Always seemed like a silly rule(who needs extra rules for blowing air at stuff). Until I was extracting air from a friend’s balloon sized thumb with a syringe to relive the pressure, and convincing him to go to the hospital. A small nick in the skin plus high pressure air(no contact from the tip even, just close).
He’s used rubber tip air nozzles at high p pressure for close to 40 years no accident.
Doesn’t anymore.
Nathan
at 100+ psi – you can shoot air through your skin and into some places on your body. think those nifty needless shot machines the military uses or like you saw on star trek back in the day.
yes it’s real. but remember – pressed to your skin – fire – ouch!@!.
why is this a relatively new osha rule – well people get hurt horsing around in the shop . . . . . I honestly believe this came from aircraft hangars and practical jokes, but such is life.
so air guns have relief systems so that when blocked – the air pressure vents. stops most practical jokers – save personal injury – save money in lawsuits.
Grady
During the 50s & 60s my father was a tool & die maker in an aircraft plant . He ALWAYS told me of a coworker that used a air hose to clean his self. A piece of rust from a pipe past through the air line and into the man. He instantly had a baseball size air bubble from his stomach to his back and he was dead in just a few seconds.
I ALWAYS think of the story when I see people clean theirselves with a air hose and when I have a air hose in hand. It’s something I wish to never witness.
Farid
Back in the early 90’s, I worked as a consultant at at a safety agency. A variation of that story was told by several instructors and OSHA trainers. Surly, some of those stories told have been copied and embellished. But, there was one similar story that was documented by an accident investigator, in which some workers were horsing around with high-pressure blower that accidentally touched a mans orifice through his cloths and caused an intestinal rupture. Ouch!!!
Farid
I forgot to mention that Back then, I learned something sobering. Almost all OSHA rules stem from accidents, often deadly. Some of the instructors and safety consultants I worked with came from manufacturing and construction industry after being involved in serious accidents.
Whenever there was uncertainty about the rules applicability or scope, we always referred back to the preamble for the rule. That’s what legal teams do as well. It can be an interesting read to delve into the discussions, correspondence, objections, and historical background behind a rule. But, just like politics, some rules get ruined by too many “sausage” makers.
Jay k.
What about hand dryers in restrooms?
Stuart
Are you asking because you use restroom hand dryers to blow stuff off your clothes and body? I don’t get your question.
Drew M
I suspect he’s referring to the Dyson hand dryers. I personally don’t like them and find the concentrated air stream painful.
Jay k.
Some of those hand dryers seem to have air blow quite fast… the exact psi, i dont know. Can that cause an air bubble or debris to go into the body?
Stuart
Oh. I thought you might have been facetious.
I don’t think restroom dryers are anything to worry about. They’re more about heated volumes of air than pressure.
There shouldn’t be a risk unless you modify the nozzle with a tapered cone and press it right up to your skin.
Nathan
note in my other comment I mention the pressure – those “air blade” style dryers don’t produce that type of pressure – but they do move a high volume. They probably do good to hit 20psi.
why is that important – well one stopping up one side of the dryer with your hand doesn’t stop the air from blowing out the other end – so built in safety.
and secondly without producing enough pressure to push through your skin – it’s also intrinsically safe. like I said it takes a good bit of pressure to blow air/fluid through skin.
Jay k.
Tnx for the replys…
Hang Fire
Stuart, thanks for the elaboration, there are many ancient air guns in circulation out there, and we all need to be informed. I received my education from working with a bench of volunteer EMT’s and CRT’s, for whom words like “abdominal inflation” and “degloving” were amusing coffee talk.
Stuart
You’re welcome!
As mentioned, this is something I tried to get a handle on before, but was unsuccessful. After writing up this post, the OSHA standards are a lot clearer and make a lot more sense.
Adam
OSHA rules aren’t to bad, try to figure them in to MSHA rules then it gets a lil more complicated because on mine sites OSHA doesn’t apply. You tools for instance can’t have an Auto lock feature to keep them running when your finger is off the trigger.
george
well, when using a blow gun, first engage brain. I had several good full blast ones and one for osha if they showed up.
De-dangerous
You can always use a blower powered contraption that by design can never exceed 3psi. It uses the weight of high volumes of air to remove dust and debris. I have one and it’s the best thing we ever did in our shop.
curt
this is a perfect example of going to ridiculous extremes when it come s the practicality of OSHA regs. I have been a safety director for 18 years and have never once seen or come across a legitimate example of an injury coming from using an air wand to blow crap of the body. blowing chips off of clothing is no more dangerous than an industrial fan blowing on a person to keep them cooled off. I know this will be met with a plethora of people who want to site regulations, but lets be real here. if you are worried about FBE’s from airborne debris then lets stop using fans, HVAC of any kind, air curtains or any other air moving apparatus. the time has come to add a bit of common sense to regulations. OSHA states that a harness and tie off is not needed in scissor lifts but I know for a fact that workers will climb a mid rail to gain reach in certain situations. Does the regulation work to truly abate the hazard in this scenario? Or does the possibility of a fall still exists? we as safety professionals really need to start applying practical solutions to the hazard at hand and stop using OSHA regs as the be all end all of safety standards. ok let me have it all you regulation junkies
AZPaul
So let me get this strait, an air nozzle can only be set a 30 psI unless it the gun has built-in pressure reducer or relief device and there is protection for the operator against chips?
Clinton Brumley
correct
Chris Manning
Do Air Lances require a trigger release type of control or can a ball vavle be used to control flow of air through air lance?
Jon Yohand
More likely to get hit by lighting in ever state on the same day then air embolism.
Peter Hunter
Hi i been using a blow air gun for the last 3 yrs blowing parts in work but holding the part now my left hand keep getting pains in it it ok at the weekend when i not in work will the blow gun do any harm to my hand thanks
Stuart
You might want to see a health care provider or occupational health specialist. I hope your hand feels better!