Compressed air system safety

Compressed air is so common that people forget it is stored energy. A pressurized receiver, a hose under load or a blow gun held against skin can all cause serious injury. Safe systems depend on sound equipment, working relief devices, proper isolation before maintenance and clear rules for how air is used at the point of work.

The main hazards

Stored energy and rupture

Air receivers, dryers, filters and piping hold energy that is released suddenly if a component fails. Corrosion inside a receiver, usually from condensate that was never drained, can thin the wall over years without any outside sign. A rupture can throw fragments and cause major damage.

Whipping hoses and flying parts

A hose that separates from its fitting under pressure whips violently. Components removed from a pressurized line, such as a filter bowl or a fitting, can be thrown with enough force to injure.

Air injection and blow guns

Air forced through the skin can enter the bloodstream or tissue and cause severe injury. Blowing air at the body, even to clean dust off clothing, is dangerous. Blow guns also drive dust, chips and debris into eyes and the air people breathe.

Noise

Open blowing, exhausts from pneumatic tools and the compressor room itself can be loud enough to contribute to hearing loss. See our guide on noise and hearing conservation.

Heat, oil and fire

Compressors run hot. Oil carryover, oily rags and poor ventilation in the compressor room add fire risk. Lubricated compressors that overheat can, in rare cases, ignite oil deposits in discharge piping.

Air quality

Plant air is not breathing air. Using compressed air to supply respirators requires a dedicated, treated and monitored breathing air system designed for that purpose.

Pressure vessels and relief devices

Air receivers are pressure vessels. In Canada, pressure equipment is regulated provincially, and depending on size and pressure a receiver may need to be registered, inspected by the provincial authority or an authorized inspector, and maintained under set rules. Alberta, BC and Ontario each have their own regulator and requirements, so check with yours.

Whatever the regulatory status, every receiver needs a working pressure relief valve sized and set for the vessel. Good practice includes:

• Relief valves that are the right rating, not plugged, capped or tied down
• Relief valves tested or replaced on the manufacturer's or regulator's schedule
• Receivers drained of condensate regularly, by automatic drains that are checked to be working
• Nameplate data readable and matched to the operating pressure
• No unapproved welding, drilling or modification of the vessel
• External corrosion, dents and damaged supports reported and assessed

Isolation before maintenance

Work on compressed air equipment must start with isolating and releasing the energy. Shutting off the compressor is not enough. Air remains in receivers, dryers and piping, and the compressor may restart automatically. A safe procedure includes:

1. Shutting down and locking out the compressor's electrical supply.
2. Closing and locking the isolation valves that feed the section being worked on.
3. Bleeding pressure through a vent or drain and confirming zero pressure on a gauge.
4. Verifying that the equipment cannot restart or repressurize before work begins.

This is part of your lockout program. See our guide on lockout and tagout for how to build and run one. Only workers trained in the procedure, and on the specific equipment, should do this work.

Safe use at the point of work

• Never point air at yourself or anyone else, and never use it to clean clothing or skin
• Use blow guns that limit outlet pressure or have safety nozzles, and use them only where cleaning with air is the right method
• Wear eye protection when using air for cleaning or with pneumatic tools
• Use hoses and fittings rated for the system pressure, and inspect them before use
• Fit whip checks or restraints on hose connections where a separation could cause injury
• Turn off and bleed the air before disconnecting a hose or changing a tool
• Keep hoses off walkways and away from vehicle traffic

Many sites find that reducing open blowing improves both safety and energy use. The leak and waste work in our guide on compressed air leaks and what they cost often goes hand in hand with these controls.

The compressor room

A tidy, ventilated compressor room is safer and lets the equipment run cooler. Keep combustibles out, keep intake air clean and cool, provide guarding on belts and couplings, and make sure the room has clear access for maintenance and emergency shutdown.

How ehZee can help

Our compressed air system inspections look at compressors, receivers, relief devices, drains, piping and points of use, and report safety and condition issues alongside efficiency findings. Where pressure equipment falls under a provincially mandated inspection, we can help you prepare for it and coordinate the follow-up work.

Common questions