1. REQUIREMENT 

    These requirements apply building-wide.

    1. Each hood or local exhaust system used to control exposure of humans to hazardous chemicals, radioactive materials, or other detrimental materials must be approved at the pre-design phase and after installation by Environmental Health & Safety (EH&S).
    2. Hoods shall be of the latest design, good quality, and produced by a reputable manufacturer. A list of acceptable hood models is maintained by EH&S.
    3. Auxiliary air hoods that have the makeup air supplied at the hood face shall not be used.
    4. Ductless hoods shall not be used for protection against chemical or radioactive materials. HEPA-filtered enclosures can be used for low-hazard particulates.
    5. Hood shall be constructed of appropriate materials resistant to chemicals and heat, and compatible with the anticipated use.
    6. Exhaust velocity at the hood face will be DESIGNED to 120 linear feet per minute (LFPM) at a sash height of 18 inches above the lower air foil.
    7. Exhaust velocity at the hood face will be BALANCED TO a minimum of 100 LFPM at a sash height of 15 inches above the lower air foil.
    8. Each hood must have an electronic flow indicator with digital readout visible to the hood user. Monitor type must allow for two-point calibration without changing hood flow. Calibration of the flow monitor will be performed during room balancing. Monitors with plug-in transformers must have a duplex outlet provided on top of the hood.
    9. Hood exhaust shall be separate from non-lab building exhaust systems. Hood exhaust can be used as part of the required lab exhaust volume.
    10. Hoods used for perchloric acid, high levels of radioactive isotopes, extreme hazard carcinogens, or pathological materials shall be exhausted separately from general laboratory fume hoods.
    11. Hood exhaust ducts shall be negatively pressurized within the building.
    12. No diversion caps (e.g., “china hat”) are allowed on hood stacks. Rain prevention extensions shall be used where rain intrusion is a potential problem. Design details are available from EH&S.
    13. Exhaust duct will terminate 16 feet above highest walking surface used for routine maintenance purposes. This determination includes all surfaces within 50 feet of stack.
    14. Booster exhaust fans in hood exhaust ducts shall not be used inside the building envelope.
    15. Backflow prevention devices shall not be installed in ducts as the only means to prevent reverse airflow.
    16. Hood filters will not be used unless absolutely required.
    17. Filter boxes will be located to allow safe and efficient access for filter change, and design will allow for safe bag-in/bag-out procedures.
    18. An adjustable gate damper (knife damper) must be provided in the individual branch duct serving each hood. It should be located such that the hood user cannot easily change the setting.
    19. Room balance and room-to-room balance shall be maintained throughout operating range of hoods.
    20. Outside air supply will be adjusted relative to exhaust air to make up for hood exhaust.
    21. When there are multiple hoods in a building use make-up and heat recovery systems and/or variable volume exhaust systems, where practicable, to maintain energy efficiency. Heat recovery system components must be able to withstand exposure to chemical exhaust without use of filters
    22. A building-wide system shall monitor and control building static air pressure.
    23. Hood interior lighting is to be uniform within the work cavity, as available from manufacturer.
    24. Light fixtures to be accessible and maintainable externally to the hood cavity.
    25. Light fixture type is to be T-8 energy efficient fluorescent type with electronic ballast.
    26. A label on each fan unit will identify all room numbers of fume hoods served. A separate label, applied on primary side of approach, will be provided with the wording “Caution – Fume Hood Exhaust”.
    27. Room identification labels are to be indelible, non-fading and installed on the north side of exterior housings whenever possible.
    28. Terminal duct sizing will provide a minimum velocity of 3000 LFPM vertical discharge.
    29. Fan vibration isolators and flexible duct connections will be used at all fan installations. Duct connections will be made using chemical-resistant materials.
    30. Noise at position of hood user will not exceed 84 dBA with system balanced for use.
    31. New hood installations will include listed chemical storage base cabinets. Wherever possible, both corrosive and flammable cabinets will be installed.
    32. Fume exhaust ductwork
      1. Ducts must be designed with materials compatible with use. The type of ductwork to be used is subject to OSU project review team assessment.
      2. Design for maximum pressures developed by the exhaust system with a 25% safety factor.
      3. Duct will be welded stainless steel in interior building spaces, except for some specialized acid wash-down applications where welded plastic will be used.
      4. Exterior roof extension will be stainless steel.
    33. Each hood or local exhaust system used to control exposure of humans to hazardous chemicals, radioactive materials, or other detrimental materials needs to have motor external of the duct system.
    34. Provide at least one accessible fume hood in each lab.
Last Updated: 
02/06/2020