The ASHRAE Standard 110-2016, “Method of Testing Performance of Laboratory Fume Hoods,” is the primary performance test used by manufacturers, laboratories, and regulatory bodies to evaluate whether a laboratory fume hood adequately contains chemical vapors. It was developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers and is referenced by OSHA, CDC, NIH, and the Joint Commission.

Unlike older tests that only measured face velocity — the speed of air moving into the hood opening — ASHRAE 110 directly measures containment performance: how much simulated chemical vapor actually escapes. This is the critical distinction. Two fume hoods can have identical face velocities yet wildly different containment performance depending on airfoil design, baffle configuration, and exhaust geometry.

The ASHRAE Standard 110-2016, “Method of Testing Performance of Laboratory Fume Hoods,” is the primary performance test used by manufacturers, laboratories, and regulatory bodies to evaluate whether a laboratory fume hood adequately contains chemical vapors. It was developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers and is referenced by OSHA, CDC, NIH, and the Joint Commission.

Unlike older tests that only measured face velocity — the speed of air moving into the hood opening — ASHRAE 110 directly measures containment performance: how much simulated chemical vapor actually escapes. This is the critical distinction. Two fume hoods can have identical face velocities yet wildly different containment performance depending on airfoil design, baffle configuration, and exhaust geometry.

The test is performed using sulfur hexafluoride (SF₆) as a tracer gas because it is non-toxic, non-flammable, does not occur naturally in laboratory air, and can be detected at extremely low concentrations (parts per billion range) using real-time monitoring equipment.

Condition the Test Space
The room must be at normal operating conditions. Cross-drafts at the hood face must be measured and recorded. HVAC must be running normally with no construction or unusual disturbances.

Install the SF₆ Release Assembly
A manifold with multiple release points is positioned on the work surface at the back of the hood interior. The gas is released at a controlled rate of 4 liters per minute throughout the test.

Position the Tracer Gas Analyzer
A real-time SF₆ gas analyzer (typically an infrared photoacoustic analyzer) is positioned to sample air at the breathing zone of a mannequin operator placed at the hood face.

Record Baseline and Run Test Sequences
The test includes static conditions, with the mannequin standing still, and dynamic conditions with arm movements simulating normal laboratory work. Each sequence runs for a defined period while the analyzer logs tracer gas concentrations continuously.

Calculate and Report Results
The 99th percentile concentration (in ppm) from the dynamic arm-movement sequence is the reported AM value. This conservative metric represents worst-case exposure during active work.

The AM value reported in an ASHRAE 110 test result represents the concentration of SF₆ tracer gas detected at the operator’s breathing zone, expressed in parts per million (ppm), as a fraction of the release concentration. The lower the number, the better the containment performance.

ASHRAE 110 does not itself define pass/fail criteria — it only defines the test method. The performance designators (AM 0.05, AM 0.10, etc.) are thresholds set by the user, the regulator, or the manufacturer.