July 2016 – Compressed Air System Hazards
Use of compressed air to power equipment and tools is quite common at many shops and construction sites. Though a great deal of attention can be placed on hazards associated with the equipment, oftentimes little thought is given to the piping system and hoses which are used to distribute compressed air. We will review three common hazards associated with these systems.
1. Compressed Air Distributions Systems Made From PVC Pipe
This hazard appears innocent enough and it can be found commonly. Sometimes misinformed people will even disagree with you because Schedule 40 PVC pipe is stamped to say it is rated for “600 PSI Water”. (Note, that’s not the same as 600 PSI Air!) PVC pipes and fittings are intended for use in plumbing applications and they are not rated or designed for high-pressure compressed air distribution systems. This is due to the fact that water under high-pressure is nearly incompressible; while air can easily be compressed. As a result, water under high pressure does not behave as violently as air does when the vessel in which they are contained ruptures. Also, PVC pipe, when exposed to temperature extremes and UV light becomes brittle over time and can shatter when subjected to high-pressure air. This sends pieces of shrapnel flying out from the system, potentially injuring workers.
2. Water Hose Clamps Used for Compressed Air Hose Connections
This is another common hazard that can be found in numerous manufacturing and construction worksites. “Worm-driven” hose clamps designed for use with water hoses often make their way into compressed air systems. They will be found splicing compressed air hoses together, connecting air hoses to quick couplers, and other fittings. OSHA requirements say that all hose and hose connections for compressed air shall be designed for the pressure and service they are subjected to. Generally compressed air hoses will utilize a crimped fitting to make their connections. Common water hose clamps are not made to withstand the same pressures as crimped fittings; they can cut into the hose itself; and are more prone to working loose when dragged across the floor. Improper connections must be avoided since they can become loose, fail, and allow the end of a pressurized hose to whip around violently striking someone before the pressure is relieved.
3. Crow’s Foot Hose Connection Without Retainer Pins or Wires
This situation results in the same hazard just discussed above. When the connection fails the air hose begins to whip violently around striking workers before pressure can be relieved. When using crow’s foot connectors the fittings must be properly matched, aligned, twisted to lock position, and pinned to prevent them from separating. The fittings are typically provided with an appropriate pin when new; but being a small part the retainer pins can often be lost and must be replaced. The retainer pin keeps the connection secure and minimizes the likelihood of the connection twisting itself open during use, separating and injuring a worker.
These are simple hazards but they are quite often overlooked. The good news is they can be easily identified and corrected. Take the time to look over your worksite and protect yourself and coworkers from hazards associated with compressed air delivery systems.
For more information on loss control services contact Jeff Rausch, email: email@example.com, P: 502-708-3124 www.RMSC.com
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