One of the most dangerous things you can do is depressurize a line full of a pressurized gas. If the charge pressure is high enough, it’s going to come roaring out, with tremendous force and velocity. Anything in its path is subject to that force & velocity. Objects small enough to become entrained in its flow can become hazardous projectiles. The noise it creates can be literally deafening. If the point of discharge is accidentally jammed against your body, the pressure can get through your skin. As if that wasn’t scary enough, the gas then has a free path inside your body…they call that an embolism, and it can kill you.
Why on earth would anyone want to do that on purpose? Well, it happens every day, in factories, businesses, and homes all over the world, when people operate compressed air operated blow off devices. Of course, there are numerous factors that can drastically reduce the risk of injury associated with compressed air blow off devices.
One of these is mandated by the government. The Occupational Safety and Health Administration (OSHA) regulates the outlet pressure of any compressed air device used in industry for cleaning purposes. Keeping the outlet pressure low mitigates the risk of puncturing the skin. There are various methods of compliance with this regulation:
- Regulate the supply pressure to less than 30psig. This absolutely complies, but it severely hampers your ability to get much done, as the air flow will be too weak to blow off anything but lightweight debris, from a smooth, dry surface, with the device pretty much right up on top of it.
- Use a device that provides a relief path for the air flow if it was to become blocked or obstructed. EXAIR engineered Air Nozzles are designed to do this…you can supply them with higher pressures but they provide a relief path for the air, meaning they can’t be blocked or dead-ended.
The same regulation – OSHA 1910.242(b) – also addresses the airborne projectile problem by mandating the use of appropriate chip guarding. There are a number of ways to do this as well…chief among these is personnel protective equipment (PPE). At a minimum, you absolutely, positively should be wearing safety glasses with side shields whenever you have a blow off device in your hand (and so should anyone working near you, for that matter). If an operator is blowing off small, sharp shards, an OSHA inspector is probably going to get grumpy if they’re not wearing a full face shield, long sleeves, and maybe even a durable apron. Alternately, the blow off device could also be fitted with guarding as well…something like the Chip Shields that are available for most EXAIR Safety Air Guns. These polycarbonate dish-shaped shields fit on a rigid extension between the Safety Air Gun and the Super Air Nozzle, and can be positioned at an optimal distance to keep solid debris and liquid being blown off away from the operator.
Another OSHA Standard – 1910.95(a) is there to protect operators against that literally deafening roar associated with unregulated discharge of compressed air. While cross-drilled nozzles (most easily seen in the lower left hand image above) provide a relief path to keep the outlet pressure at a safe level if they’re dead-ended, they’re still for all intents & purposes, an open-ended blow off…and quite loud. EXAIR Super Air Nozzles reduce the sound level of their air flow by design…the entrained air (which makes them so efficient) also forms a lower velocity barrier layer in the flow, which makes them extraordinarily quiet. In fact, all EXAIR Super Air Nozzles except our largest High Force models comply with OSHA limits for 8 hour noise exposure limits. Most callers that we talk to about applications for those are in areas where hearing protection is mandated anyway…if you need more than 4 pounds of blowing force, you’re probably wearing ear plugs already.
If you use compressed air for cleaning, drying, blow off, etc., you really need to do it safely, and in compliance with published & established safety standards. OSHA WILL fine you otherwise, and, even worse, someone could get hurt. EXAIR Corporation is devoted to helping you get the most out of your compressed air usage, and safe use is key to that. If you have any questions about it, give me a call.
Russ Bowman, CCASS
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