JSNN Laboratory Local Exhaust Ventilation Program

1. General

This Program is intended to bring all stakeholders in a collaborative approach toward establishing a Local Exhaust Ventilation Management Program (LEVMP). Laboratory fume hoods are the most important engineering control devices in research lab environments for preventing or minimizing exposure to airborne hazardous materials that are generated during the course of experiments or as a result of an incident or spill. These include liquids, gases, vapors, and particulate matters, including nanomaterials. Hazardous materials shall only be used inside a tested and functional exhausted fume hood. Other exhaust devices, including recirculated air (ductless) fume hoods, snorkels, gas cabinets, and exhaust enclosures are also used for limited applications in controlling and exhausting heat, odorous, and low hazard chemicals in low volume applications. Using any exhaust device other than an exhausted fume hood requires ROEHS review and approval.

Users must receive proper training, understand different exhaust devices and their application and limitations, and make sure that devices are used properly and based on their intended design. This program can only become successful if all users and stakeholders recognize and fulfill their roles and responsibilities.

2. Roles and Responsibilities

a. PIs

  • Make sure all users have received updated training on proper use of the fume hoods and other local exhaust devices.
  • Make sure that users understand the application and limitations and apply all required safety precautions and good work practices when utilizing the equipment.
  • Report all deficiencies, malfunction, and safety concerns to JSNN Research Operations and Environmental Health and Safety (ROEHS.

b. Users

  • Follow all guidelines provided in fume hood training.
  • Properly use the equipment based on their intended use as well as its limitations.
  • Receive proper safety and fume hood use training.
  • Avoid any misuse, alteration, or modification that may impact hood performance.
  • Report all deficiencies, malfunction, and safety concerns to the PI.
  • Avoid using fume hood or other exhaust devices that indicate insufficient flow through an alarm mechanism or a warning sign posted by ROEHS.


  • Performs bi-annual local exhaust inspections.
  • Provides training for users.
  • Issues work orders and follow ups on identified and reported deficiencies.
  • Develops and maintains local exhaust ventilation management program.
  • Communicates with Facilities Maintenance to ensure that proper preventive maintenance, calibration, and communication/tag-out procedures are in place during repair.

d. Facilities Maintenance

  • Responds to the issued work orders in a timely manner.
  • Communicates with ROEHS on any maintenance, shutdown, or system malfunction issues.
  • Maintains the mechanical, electrical, and electronic control systems fully functional and calibrated.
  • Develops a preventative maintenance program in compliance with JSNN local exhaust ventilation program requirements.

3. Equipment selection, installation and modification

Any new local exhaust ventilation system or the modification of an existing device or system requires JSNN ROEHS review and approval. This is critical for making sure that equipment meets applicable codes and standards, provides sufficient/intended protection, and is compatible with the building system and existing exhaust/supply capacity. 

4. Fume hood performance test

All fume hoods are inspected by JSNN ROEHS on a semi-annual schedule. All other exhaust devices are checked annually. Additional tests are performed for new installations, upon work order closure/post repair, after major modifications, or upon a user’s request.

5. Material and test equipment

a. Materials

  • Fog generating liquid
  • Hood operating status labels

b. Tools and equipment

  • TSI VelociCalc (hot-wire anemometer)
  • Small volume smoke generator
  • Tape measure

6. Local exhaust ventilation system test procedures

a. Constant Air Volume (CAV)

  • Fave velocity test
    • Set the VelociCalc at the 5-10 seconds interval set point.
    • Close the horizontal sash openings (if applicable).
    • Open the vertical hood sash to 18 inches (or lower for fixed sash height designs).
    • For manifold hoods, make sure all hoods inside the room are running with sash raised at 18” sash height (or lower for fixed sash height designs).
    • Make sure the lab door is kept closed during the test.
    • Divide the hood face opening into imaginary 1’ x 1’ grids. Using the hot-wire anemometer, measure the face velocity at the center of each grid. In the absence of a ring stand, use an articulated probe, rested on the sash (for upper row readings) or airfoil (for lower row readings). For satisfactory test results, the average of the readings (average face velocity) must fall between 90 fpm and 120 fpm.
    • Investigate the cause, if single readings are not within ± 20% of the average face velocity.
  • Cross drafts measurement
    • Measure the cross draft, as specified in the ASHRAE 110 test method. Investigate/correct cross drafts more than 50% of the average face velocity (ideally more than 30%).
  • Room pressurization test
    • Check the room pressurization with the hood sash at 18” (or lower for fixed sash height designs). Report if room pressurization is positive, too negative (10 fpm or more, measured at the room’s full door opening face, when all doors are fully open), or fluctuating compared to the hallway/adjacent non-lab areas.
  • Fume hood monitor/alarm check
    • Check monitor digital readout (if applicable) and audible/visible alarm functions.
    • Check mute button and any other monitor/ alarm functions
    • The low flow alarm should be set at 70 fpm (50 fpm for ductless hoods). High velocity alarms must be disabled.
  • Additional room and hood environment check
    • Supply diffuser location to the fume hood.
    • Fume hood location to the door, high traffic areas, or any other source of cross drafts.
    • Sash’s smooth movement check.
    • hood light switch
    • Electrical outlets
    • Airfoil integrity
    • Back baffle and side panels installation
    • Hood – work surface joints sealing
    • Any user’s modification or alteration, including air foil or back baffle blockage, obstacles, large equipment, or overloaded fume hoods.

b. Recirculating (ductless) hoods

  • Recirculating air hoods have several use/application limitations and must be approved by ROEHS before purchase.
  • Test procedure for the recirculating fume hoods is identical to the CAV hood test method. However, the average face velocity for ductless fume hoods must fall between 55-70 fpm.
  • In addition to test procedures for CAV hoods, recirculation hoods’ filter capacity, fan function, and chemical detection monitor function need to be verified.

c. VAriable Air Volume (VAV) hoods

  • The following tests are required for the VAV hoods, in addition to the tests performed for the CAV hoods
    • Repeat the face velocity measurement at 13” sash height. Check if average face velocity stays rather constant, when compared to the measurement results at 18” (± 20%). Report drifts as “VAV valve/control modulation malfunction”
    • Whenever applicable, check the hood zone presence sensor, emergency purge button, and sash position alarm.
    • Check the room pressurization with all hood sashes at 18” and repeat with all sashes closed.

7. Fume hood test pass and fail criteria

a. Green Sticker: Meets JSNN requirements

  • Fume hoods must have an average face velocity of 90 to 120 fpm (55-70 fpm for ductless hoods) with the sash at 18” from the hood work surface (or lower for fixed sash height designs). All hoods must pass a local visualization (smoke) test to meet the requirements. Capture of all smoke within 6 inches of the hood face (inside the hood) at 18” (or lower for fixed sash height designs) sash height is required to meet the standard.
  • All hoods and room environment elements/components impacting hood containment and performance, including sash movement, cross draft velocity, VAV control systems function, and hood loading and layout/obstruction meet the requirements.

b. Red Sticker: Does Not Meet JSNN requirements (Do Not Use)

  • Any hood with an average face velocity of 89 fpm or less at 18” (or lower for fixed sash height designs) sash height.
  • Any recirculating hood/ductless hood with average face velocity of 54 fpm or less
  • Hoods defective for reasons other than face velocity such as failure of the local visualization smoke test, a non-operational sash, strong (50 fpm or more for exhausted hoods and 30 fpm or more for ductless hoods) cross draft, or a missing sash/baffle.
  • Hood is out of service and shall not be used until it’s fixed and verified by ROEHS
  • A “Do Not Use” sign will be posted to the sash. This sign stays posted until the hood is fixed and velocity is checked and verified by ROEHS. Only ROEHS is allowed to remove the sign after verification (tag-out procedure)

c. Blue Sticker: Does Not Meet JSNN requirements

  • Hoods that have average face velocities above120 fpm@18” (or lower sash height for fixed-sash hoods. This number is 70 fpm for ductless hoods).
  • While some studies indicate loss of containment at 150 fpm or higher face velocities, blue stickers are mostly issued for energy conservation and room air optimization purposes.
  • Users can continue using the hoods posted with a blue sticker, while work order for face velocity adjustment is in progress.

8. Work order procedure

a. ROEHS issues a work order for deficiencies found/reported

  • For fume hood performance /containment-related work orders, ROEHS will post the hood with a “Warning, Do Not Use Sign”.
  • ROEHS will notify the PI when the hood is out of service.
  • This sign will remain posted until the hood is fixed and revisited by ROEHS. Signs must only be removed by ROEHS once hood performance is found satisfactory (tag-out procedure).
  • ROEHS will notify PI when the hood is back to normal operation.

9. Applicable Standards

  1. 29 CFR Part 1910.1450, “ Occupational Exposures to Hazardous Chemicals in Laboratories’”
  2. ASHRAE 110 (latest version) “Method of Testing Performance of Laboratory Fume Hoods”
  3. ANSI Z9.5 (latest version) “Laboratory Ventilation” standard
  4. NSF 49 1992 “Class II (Laminar Flow) Biohazard Cabinet”