ASHRAE 110: What You Need to Know About Fume Hood Safety Inspections

The main purpose of installing a fume hood in a laboratory is safety. It’s that simple. The better the fume hood, the safer the employee and when it comes to toxic chemicals and tracer gases, you can’t be too careful. Because the safety standard is so high for labs, it’s not only critical to have your fume hood testing annually, it’s also illegal not to. The fume hood testing standard is known as the ASHRAE 110 and here’s what you need to know about.

There are three things that the tester is checking when performing a fume hood safety inspection: flow visualization, face velocity, and tracer gas performance. The measuring scale is broken down into four ratings which are “fail, poor, fair and good” and of course the aim of the test is for the fume hood to rate “good” which ensures lab safety and compliance.

Flow visualization consists of two tests known as local smoke and gross smoke. These names are self-explanatory in that the tester utilizes smoke to check for leaks, or cracks in the fume hood, structural defects, air flow inefficiency or other issues that may allow gas to escape. A smoke gun is used to perform this test but the gross smoke measurement is done on a macro level in which a smoke bomb is detonated in the middle of the fume hood. If any smoke escapes out of the front of the hood during either test, the fume hood will receive a “fail” rating and appropriate action must be taken to rectify it.

Face velocity is the measurement of air flow through the fume hood. Different fume hoods have face velocity specifications for ventilating gases and it’s important that the fume hood maintain these levels. Otherwise, it’s considered compromised and unsafe. This test is performed with the sash open 25%, 50% and 100% using a device that measures air flow at different place within the hood. Those readings are then compared to the manufacturer’s specifications for that fume hood to ensure complete functionality.

The tracer gas test is performed to check for leaks within the hood. A mannequin in placed in front of the hood in different places for five minutes at a time. The sash is opened and closed accordingly, and the data is collected using a probe attached to the mannequin. If the probe measures more than .05 ppm (parts per million) of tracer gas, the fume hood receives a “fail” rating.

For a lab to be considered “safe” the fume hood must function properly, efficiently, and safely, hence the testing. The fume hood is a machine, after all, and thus subject to the same level of wear and tear as any other manufactured product. Annual testing ensures that your fume hood is durable but, more importantly, that it’s safe to operate. The ASHRAE 110 test confirms this safety and guarantees compliance with governmental and industry standards.