Human as Mannequin Tests

The purpose for a fume hood is to contain and remove toxic or hazardous materials within the hood, to ensure the scientist is working in a safer environment according to the relevant health hazard exposure guidelines, such as OSHA PEL's, NIOSH.

It has long been recognized that many factors will affect a fume hood's performing ability, included design of hood, sash movement, room air-flow rate, user activity, and etc. Ashrae 110-1995 test standard is the most widely used test method for evaluating a hood's containment performance, with a tracer gas detector placed at the mannequin, simulating the human breathing zone. However, user activity that actually affect the containment of hood is not examined. To ensure the fume hood is actually safe, researcher has recently established the Human-as-mannequin test(HAM test), simulating actual operator's hand and arm movements through manipulations of objects within a fume hood that may cause loss of containment. This challenge, is counting on the ability of the hood to contain, capture and remove the contaminants.

During the experiment, tracer gas detector is placed near to the operator's breathing zone and averaged over the test period. The tracer gas release in the whole experiment is maintained at a level of 4L/min. Hands and arms movement are in a rate of one foot per second, and all movement are conducted individually each time. Operator will first insert their hands and arms into the hood, and removed from the hood. The experiment will carry on by moving the objects from the resting position to a new position(Picture 1), and exchanging objects placed behind the ejector(Picture 2). After removing their hands and arms, operator will rotate his body as required. All above movements are repeated in the center, left side and ride side in the fume hood.

HAM test can be customized according to the type of fume hood and the motion or operation for experiment needs, but it has yet no industry standards for comparison and no recommended threshold values for pass and fail. Therefore, thresholds may be established by the testing hoods facility.

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