What happened? A small carbon monoxide (CO) leak was detected during a routine laboratory safety inspection (see photos below). CO levels at the leak were >1000 ppm. CO levels in the extremely well ventilated lab were 2-3 ppm. The recommended exposure limit for CO is 25 ppm, as an 8-hour, time-weighted average (TWA).
While the leak was not significant from an occupant exposure standpoint, it was a warning of greater possible risks. Carbon monoxide (PDF format) is a toxic and flammable gas that can cause illness, permanent neurological damage, and death. Because it is colorless, odorless, and nonirritating, CO can overcome exposed persons without warning. Often there is little time before they experience symptoms that inhibit their ability to seek safety.
Why did it happen? A CO cylinder was inappropriately stored and plumbed outside of an exhausted enclosure.
How can a similar occurrence be avoided? Carbon monoxide is an extremely hazardous chemical that requires prior approval (Chemical Safety Level 3 or CSL-3) by the Institutional Chemical Safety Committee (ICSC). For approval, the Minimum Requirements for Toxic/Corrosive Gas Use (PDF format) will at least be required by the ICSC, which includes locating the cylinder in an appropriate exhausted enclosure and special piping and hazard warning considerations.
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Above Left – Carbon monoxide (CO) cylinder (100% CO) outside of a fume hood.
Above Right – Regulator pressure gauges show the cylinder valve is open and the flow control valve is closed. A leak was detected between the regulator and the flow control valve (leak location indicated by the red arrow). Note the draped Tygon tubing and barbed fitting which are also leak risks (the tubing can easily come off the fitting or fall out of the hood).
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