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ANSI/ASHRAE 110 is the national standard that measures how well a laboratory fume hood contains hazardous fumes, using face velocity readings, smoke visualization, and tracer gas containment testing. Most labs need this testing performed at least annually to satisfy NFPA 45 and to support compliance with OSHA's Laboratory Standard.
Fume hoods look simple from the outside. A hood that passes on paper can still leak contaminants into a technician's breathing zone if the sash height, airfoil, or exhaust balance is off by a small margin. ASHRAE 110 exists to catch the gap between a running fan and a hood that protects the person standing in front of it. Below is what the standard covers, how a certified technician runs the test, and what a lab should expect on testing day.
What Does ANSI/ASHRAE 110 Require?
ANSI/ASHRAE 110-2016 (reaffirmed 2025) is a quantitative and qualitative test method for evaluating conventional, bypass, auxiliary air, and variable-air-volume (VAV) laboratory fume hoods (ANSI Blog). It defines three separate testing scenarios, each answering a different question about the hood's performance:
- As Manufactured (AM): Testing performed at the factory, under controlled conditions, before the hood ships.
- As Installed (AI): Testing performed after the hood is installed in its final location, before lab operations begin. This step catches problems the factory test cannot see, like cross-drafts from a nearby supply diffuser or a room pressurization imbalance.
- As Used (AU): Testing performed with the hood in active service, equipment and materials in place, reflecting the conditions a lab worker experiences day to day.
The 2016 revision moved the tracer gas breathing zone measurement point to 22 inches above the work surface, based on updated research on where an operator's face sits during hood use (Labconco). It also requires digital data logging during the test rather than handwritten readings, which reduces transcription error and gives the lab a verifiable record.
What Gets Measured During the Test?
A full ASHRAE 110 evaluation covers three categories of measurement, and a technician typically runs all three during the same site visit.
Face velocity. The technician takes multiple-point velocity readings across the sash opening using a calibrated, NIST-traceable anemometer, then calculates the average and checks for outlier readings at any single point. Most institutional programs target an average face velocity in the 80 to 120 feet-per-minute range, with a minimum of around 70 fpm at any individual measurement point (UC Riverside EH&S). Too slow, and fumes escape into the room. Too fast, and turbulence at the sash can pull contaminants back out toward the operator, which is a common misconception about hood performance.
Smoke visualization. The technician releases a visible smoke stream at the sash opening and at the interior of the hood to watch how air moves. This step reveals turbulence, dead zones, and reverse airflow that a face velocity number alone will not show, especially in VAV hoods, where velocity readings can look correct while the airflow control sequence does not respond the way it should (AIHA Synergist).
Tracer gas containment. This is the most rigorous part of the test. The technician releases a tracer gas, historically sulfur hexafluoride (SF6), inside the hood at a controlled rate and measures how much escapes to the operator's breathing zone using a detector. SEFA's acceptance criteria call for an average containment loss of 0.05 ppm or less for As Manufactured testing, and 0.10 ppm or less for As Installed and As Used testing (Labconco). SF6 is a potent greenhouse gas, so some labs and states are shifting toward isopropyl alcohol with a photoionization detector as a lower-impact alternative that produces comparable results (AIHA Synergist).
How Often Does a Fume Hood Need to Be Tested?
NFPA 45 sets the baseline: laboratory hoods and their exhaust systems need inspection and testing at least once a year, with a dated label or log posted on the hood showing the last test date, the measured average face velocity, and the required retest interval (Boka Lab Furniture, NFPA 45 guide). Hoods used with regulated carcinogens often fall under a shorter interval. Cal-OSHA Title 8, Section 5209, for example, requires semiannual testing for those hoods regardless of the general annual baseline (UC Riverside EH&S).
OSHA's Laboratory Standard, 29 CFR 1910.1450, does not spell out its own numeric test interval. It requires that fume hoods and other protective equipment function properly, and points to ANSI Z9.5 and ASHRAE 110 as the consensus standards that define what functioning properly means in practice (OSHA). In effect, the annual (or more frequent) testing cadence in NFPA 45 becomes the practical benchmark OSHA inspectors expect to see documented.
Who Performs ASHRAE 110 Testing, and What Happens if a Hood Fails?
Testing is generally performed by a qualified environmental health and safety office, an in-house facilities team trained to the standard, or an outside specialty contractor with calibrated instrumentation and documented ASHRAE 110 procedures. Universities and larger research institutions often run an internal program; many hospitals, pharmaceutical facilities, and smaller labs contract the work out to a testing, adjusting, and balancing (TAB) firm.
When a hood fails to meet the required face velocity or containment thresholds, the standard practice looks like this:
- An "Out of Service" notice is posted directly on the hood.
- Hazardous materials inside the hood are removed and stored properly elsewhere.
- A work order is submitted describing the deficiency, whether that's a mechanical airflow problem, a damaged airfoil, a sash tracking issue, or a building pressurization conflict.
- The hood stays offline until the underlying issue is corrected and the hood is retested and documented as passing (UC Riverside EH&S).
The consequences of skipping this process are serious. Inhalation of toxic fumes ranks among the leading hazards in laboratory settings, and OSHA can cite a facility under 1910.1450 when protective equipment is not verified as functioning (ANSI Blog). One frequently cited industry estimate puts hood failure rates at 15 to 30 percent during routine testing, which is a meaningful share of hoods operating below the protection level assumed by lab staff (AIHA Synergist).
Fume Hood Test Types and Face Velocity Reference
| Test Type | When Performed | What It Reveals | Typical Acceptance Criteria |
|---|---|---|---|
| As Manufactured (AM) | At the factory, before shipment | Baseline hood performance under controlled conditions | Average containment loss of 0.05 ppm or less |
| As Installed (AI) | After installation, before use | Room airflow, cross-drafts, exhaust balance issues introduced by the installation | Average containment loss of 0.10 ppm or less |
| As Used (AU) | During active lab operation | Real-world performance with equipment, materials, and operator movement present | Average containment loss of 0.10 ppm or less |
| Face Velocity (general chemical use) | Every test cycle | Whether exhaust volume matches the sash opening | Average of roughly 80 to 120 fpm; minimum near 70 fpm at any single point |
Frequently Asked Questions
How often should a fume hood be certified under ASHRAE 110?
NFPA 45 requires annual testing at minimum for most laboratory fume hoods, with each hood carrying a dated label or log showing the last test date and results. Hoods used with regulated carcinogens are commonly tested on a semiannual schedule under state-level rules such as Cal-OSHA Title 8, Section 5209.
What is the difference between As Manufactured, As Installed, and As Used testing?
As Manufactured testing happens at the factory before the hood ships. As Installed testing happens after the hood is placed in its final location and before lab work begins, catching installation-specific problems like cross-drafts. As Used testing happens during normal lab operation, with equipment and materials in the hood, to measure the containment level a worker experiences day to day.
What face velocity does a fume hood need to pass ASHRAE 110 testing?
Most programs target an average face velocity in the 80 to 120 feet-per-minute range across the sash opening, with a minimum of roughly 70 fpm at any single measurement point. The correct target depends on the hood type, the chemicals in use, and the institution's own written safety program.
Why is tracer gas used instead of measuring face velocity alone?
Face velocity tells a technician how fast air moves across the opening, but it does not show whether that airflow keeps contaminants inside the hood. Tracer gas testing releases a gas at a controlled rate inside the hood and measures how much reaches the operator's breathing zone, which is a direct measurement of containment rather than an indirect proxy.
What happens if a fume hood fails its ASHRAE 110 test?
The hood is taken out of service immediately, hazardous materials are removed and stored elsewhere, and a work order is issued to correct the deficiency. The hood stays offline until it is repaired and retested to a passing result, and the failure and correction are documented.
Who is qualified to perform fume hood testing?
Testing is performed by environmental health and safety staff, trained facilities personnel, or an outside testing, adjusting, and balancing contractor using calibrated, NIST-traceable instrumentation and documented ASHRAE 110 procedures. The technician running the test should be able to produce a certification record showing face velocity, smoke visualization results, and containment data for the specific hood tested.
Where to Start
Fume hood certification is one piece of a larger life-sciences compliance picture, alongside pressurization verification, airflow balancing, and damper testing across a facility. Aero Performance Group's compliance testing services cover fume hood certification as part of that broader program, with calibrated instrumentation and documentation built to satisfy NFPA 45, OSHA, and institutional EHS requirements.
If a lab is due for annual certification, moving into a new space, or troubleshooting a hood that already failed an internal check, getting ahead of the testing cycle keeps the facility compliant and keeps lab staff protected. [Request a fume hood testing assessment]