ASHRAE 110 Tracer Gas Testing
Fume hood performance is typically evaluated qualitatively by subjecting the hood to smoke tests and measuring the velocity profile. The most accurate and quantitative standardized fume hood test protocol available today is the ASHRAE 110 test.
Very few companies in North America can offer this test due to the specialized equipment and skill required. Con-Test has been performing ASHRAE 110 tests for customers across Canada for many years and we are proud to be one of those very few companies with that capability.
An ASHRAE test is currently the most comprehensive test for fume hood performance. These tests are typically done in the factory where the hoods are produced however a fume hood may pass an ASHRAE test in the factory but the environment into which it is installed may adversely affect its performance.
Some of the factors that may affect performance include:
- Room cross drafts (from open windows or doors, supply diffusers, fans, etc.),
- Room air pressure relative to adjacent rooms,
- Installation deficiencies or,
- Performance issues relating to the building’s ventilation system.
More and more Health and Safety departments are recognizing the importance of verifying a fume hood’s performance after it is installed. This is being done by including ASHRAE testing in their health and safety “SOP”s for fume hoods when they are installed and periodically thereafter.
The ASHRAE 110 test combines
- A smoke/flow visualization test,
- A velocity profile, and
- A tracer gas test, to arrive at an overall assessment of a fume hood’s performance.
The objective of the smoke test is simply to see if any smoke escapes the hood. Other information provided from this test includes how well the hood draws air towards the back of the hood and away from the user and how well the hood captures air through the face opening. All this information together provides a qualitative indication of the hood’s containment ability.
A velocity profile is then conducted to provide an indication of the hoods performance by taking measurements in the vertical plane where air enters the hood. Several velocity measurements are taken with a single point “hot-wire” probe to ensure a representative inflow average velocity number is obtained.
The tracer gas test provides a quantitative measure of the hoods containment ability. The test uses a gas detector instrument that is capable of measuring small concentrations of a tracer gas like Sulfur Hexaflouride (SF6). A mannequin is placed outside the hood to simulate the presence of a person who would typically be standing in the hood air inflow.
Test results are provided in both a numerical and graphical format to quickly determine if the hood is in fact providing adequate containment for the user.