How do I certify my fume hood?

Fume hoods undergo a rigorous certification process when they are manufactured to ensure they meet state, federal, and international certification guidelines in addition to meeting or exceeding the current ISO9001 standards. Fume hoods must be tested both annually and after any ventilation system adjustment to confirm their operation is satisfactory. These tests are designed with specific procedures to evaluate the airflow velocity, airflow monitors, cross-craft flows, airflow gauges, tracer gas containment, and more. With all that said, what exactly does fume hood testing include?

Any inspection to certify a fume hood will include the following:

• Testing through airflow visualization with a smoke test and testing through face velocity measurements.
• A visual inspection of the fume hood including sash and baffle performance and overall condition.
• Fume hood monitor performance.
• Fume hood testing certification stickers.

In this article, we’re going to dive into these four steps and see what each entails.

Visual Inspection

The visual inspection of a fume hood includes specific criteria. The first order of business is sash operation, ensuring free movement and no binding. The sash must be stable enough to remain at a set height without additional support and meet the following general safety standards:

• Stops are verified and installed in a way to prevent rising beyond the maximum sash opening or an otherwise safe operating height specified on the use of certification stickers.
• Constructed of both shatterproof and transparent materials.
• Easily movable and free of physical defects.

A final touch to the visual inspection is a general lookover to discover any corrosion, fouling, or other defective condition that would affect user safety.

Performance Testing

When testing a fume hood’s performance, you will need to complete the following tests: airflow visualization, face velocity, and a response test for any variable air volume (VAV) system. Let’s break down these three tests to better understand the procedure:

• As outlined in ANSI/ASHRAE 110-1995: Methods of Testing Performance of Laboratory Fume Hoods and ANSI/AHIA Z9.5-2012, airflow visualization tests require the following:
  • When the plane of the sash is placed 6 inches into the hood, there should be no visible escape.
  • Factors such as reverse flow, vortex regions, stagnation zones, escape, and clearance are easily identified by smoke generation.
  • The sash should be moved up and down during the smoke test to confirm the fume hood’s dynamic ability.
• Face velocity testing should be performed. All face velocities are to be collected when sash height is at 18 inches, which is standard working operator height. An average of 80-150 FPM at a sash height of 18 inches is a passing velocity. 100 FPM is considered an ideal velocity for laboratory fume hoods.
• VAV system verification testing will include the following:
  • Response tests to confirm adequate decrease and increase of air flow to allow easy maintenance of the air velocity.
  • Stabilization tests ensure appropriate flow rate with a proper response time when the sash movement is completed.

Monitor Performance

Performance monitor testing is straightforward. Fume hood monitors are calibrated based on a system of annual face velocity readings with low and high alarms set to coordinate with the readings collected.

Certification Stickers

Annual performance verifications include stickers that are applied to all fume hoods. Each sticker confirms the test was completed and methodology used as well as identifying the unit itself. The sticker will also display the average face velocity recorded at the operating height of 18 inches, the date the test was completed, and the name of the person who performed the test.

Suppose a fume hood fails the performance test. In this instance, EH&S is informed, and the unit is tagged out with a clear “Notice of Failure” sign. EH&S will then notify the owner and arrange a repair with Facilities Management and Planning. You should contact EH&S immediately if your lab’s fume hood has not been tested within the last year or if you observe any indication that the hood is not operating properly.

DigeLab specializes in keeping your lab facilities safe, certified, and repaired. It’s our honor and privilege to provide the highest caliber of safety and technical consultation. If you are in need of fume hood installation, cleaning, or maintenance and would like to learn how DigeLab Solutions can help, please call or send an online request. We look forward to working with you!