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Design Criteria for Laboratories

  1. Other Laboratory Equipment

    1. Biological Safety Cabinets

      The type, intended use and location of BSCs, in institutions with a Biosafety Committee and a Biosafety Officer, shall be approved by the Biosafety Officer prior to specification, purchase and installation.

      Biological safety cabinets (BSC), laminar flow bench hoods (LFB), and glove boxes require appropriate design and installation criteria. Those purchased and installed at USG institutions shall be in compliance with that criteria, as outlined in National Sanitation Foundation (NSF) International Standard #49 (most current version), Class II (Laminar Flow) Biohazard Cabinetry and “Biosafety in Microbiological and Biomedical Laboratories”, U.S. Dept. of Health & Human Services (most current version).

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    2. BSC Descriptions

      1. Design protection.

        Biological safety cabinets (BSCs) are designed to protect the operator, the laboratory environment and work materials from exposure to infectious aerosols and splashes that may be generated when manipulating materials containing infectious agents such as primary cultures, stocks and diagnostic specimens. The following information was adapted from the National Sanitation Foundation (NSF) Standard 49, the World Health Organization (WHO) “Laboratory Biosafety Manual”, and the Centers for Disease Control and Prevention (CDC), and National Institutes of Health (NIH) joint publication, “Primary Containment for Biohazards: Selection, Installation and Use of Biological Safety Cabinets”.

      2. Cabinetry types and classes.

        BSCs, when properly used, have been shown to be highly effective in reducing laboratory-acquired infections and cross-contaminations of cultures as well as protecting the environment.

        The primary means used to accomplish this, and one of the major differences between a BSC and a chemical fume hood, is by utilizing high-efficiency particulate (HEPA) filters. The HEPA filter traps 99.97% of particles of 0.3 µm in diameter and 99.99% of particles of greater or smaller sizes. This enables the HEPA filter to effectively trap all known infectious agents and ensure that only microbe-free exhaust air is discharged from the cabinet.

        There are three classes of BSCs, which are discussed below. Please note that horizontal and vertical outflow cabinets (i.e. clean-air work stations) are not BSCs and should not be used as such.

        1. Class 1 BSC: A ventilated cabinet for personnel and environmental protection, having an un-recirculated inward airflow (75 ft/min) away from the operator that exhausts all air to the atmosphere after filtration through a HEPA filter. Class I cabinets are suitable for work where no product protection is required and can be used with volatile toxic chemicals and volatile radionuclides.

        2. Class II BSC: A ventilated cabinet with inward airflow for personnel protection, downward HEPA filtered laminar airflow for product protection, and HEPA filtered exhausted air for environmental protection.

          There are four types of Class II BSCs:

          Type A1 – Maintains a minimum average inflow velocity of 75 ft/min with HEPA filtered downflow air that is a portion of the mixed downflow and inflow air from a common plenum. Approximately 70% of the air recirculates through the supply HEPA filter back into the cabinet’s work zone with the remaining 30% passing through the exhaust HEPA filter into the room or the outside through a thimble connection. Contaminated ducts may be under positive or negative pressure without negative pressure plenums. Type A1 cabinets are not suitable for work with volatile toxic chemicals and volatile radionuclides.

          Type A2 – Maintains a minimum average inflow velocity of 100 ft/min with HEPA filtered downflow air that is a portion of the mixed downflow and inflow air from a common plenum. Approximately 70% of the air recirculates through the supply HEPA filter back into the cabinet’s work zone with the remaining 30% passing through the exhaust HEPA filter into the room or the outside through a thimble connection. All biologically contaminated ducts and plenums are under negative pressure or surrounded by negative pressure ducts and plenums. Type A2 cabinets are suitable for work with minute quantities of volatile toxic chemicals and trace amounts of radionuclides when air is exhausted through properly functioning exhaust canopies (i.e. thimble connection).

          Type B1 – Maintains a minimum average inflow velocity of 100 ft/min with HEPA filtered downflow air composed largely of uncontaminated recirculated inflow air. Approximately 30% of the air recirculates through the supply HEPA filter back into the cabinet’s work zone with the remaining 70% passing through the exhaust HEPA filter to the outside through a dedicated duct. All biologically contaminated ducts and plenums are under negative pressure or surrounded by negative pressure ducts and plenums. Type B1 cabinets are suitable for work with minute quantities of volatile toxic chemicals and tracer amounts of radionuclides.

          Type B2 – Maintains a minimum average inflow velocity of 100 ft/min with HEPA filtered downflow air drawn from the laboratory or the outside air. All inflow and downflow air is exhausted to the outside after filtration through a HEPA filter without recirculation into the cabinet’s work zone or return to the laboratory. All biologically contaminated ducts and plenums are under negative pressure or surrounded by negative pressure ducts and plenums. Type B2 cabinets are suitable for work with volatile toxic chemicals and volatile radionuclides.

        3. Class III BSC: A totally enclosed, ventilated cabinet of leak-tight construction (a.k.a. “Glovebox”). Activities inside the cabinet are conducted through attached rubber gloves. The cabinet is maintained under negative air pressure of at least 0.5 inches water gauge (120 Pa). Downflow air is drawn into the cabinet through HEPA filters, and exhaust air is treated with double HEPA filtration or by HEPA filtration and incineration.

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    3. BSC Considerations

      1. Selection.

        A BSC should be selected primarily in accordance with the type of protection needed: product protection; personnel protection against Risk Group 1-4 microorganisms; personnel protection against exposure to radionuclides and volatile toxic chemicals; or a combination of these.

      2. Location.

        The velocity of air flowing through the front opening into a BSC varies between 75 and 100 ft/min, depending on the Class and Type of cabinet. At this range of airflow velocity, the integrity of the directional air inflow is fragile and can be easily disrupted by air currents generated by people walking close to the BSC, open windows, air supply vents, and opening and shutting doors.

        Ideally, BSCs should be situated in a location remote from traffic and potentially disturbing air currents. A clearance of at least 6 inches is needed on each side of a cabinet for service fixture access. When possible, a 1-foot clearance should be provided behind and on each side of the BSC to allow easy access for maintenance. A clearance of 18 inches above the BSC may be required to provide for accurate air velocity measurements across the exhaust HEPA filter and for exhaust HEPA filter changes.

      3. Service fixtures installation and clearance.

        Service fixtures required shall be installed properly and perform acceptably. These require a minimum of 6 inches clearance on each side of a cabinet for maintenance access. Overhead clearance for exhaust air discharge should be 18 inches from the ceiling.

      4. Unwrapping of cabinets.

        New cabinets shall not be unwrapped until dust-creating activities are completed within the laboratory.

      5. Initial certification of BSC.

        Initial certification of cabinet performance shall be performed by an accredited certifier before cabinet use.

      6. Certification parameters.

        1. The functional operation and integrity of each BSC should be certified to NSF 49 specifications at the time of installation and annually thereafter by qualified technicians.

        2. Evaluation of BSC containment effectiveness includes tests for:

          1. Cabinet integrity
          2. HEPA filter leaks
          3. Down-flow velocity profile
          4. Face velocity
          5. Negative pressure / ventilation rate
          6. Air-flow smoke pattern
          7. Alarms

          8. Interlocks

        3. Optional tests which may also be conducted include:

          1. Electrical leaks
          2. Lighting intensity
          3. Ultraviolet light intensity
          4. Noise level

          5. Vibration

      7. Operation of BSC.

        Most BSCs are designed to allow operation 24 hours a day.

        1. Class II A1 and A2 BSCs exhausting to the room or connected by exhaust canopies (i.e. thimble connections) can be turned off when not in use.

        2. Class II B1 and B2 BSCs, which have hard-ducted installations exhausting to the exterior, must have airflow through them at all times to help maintain room air balance.

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    4. Emergency Safety Showers

      1. Plumbing requirements.

        Plumbed safety showers shall be properly installed, within a 10-second walking time from the location of any hazard within the laboratory area.

      2. Activation valve.

        Each shower shall have a manual activation and shut-off valve within easy reach of the shower head. Overhead valves shall have a rigid pull rod with handle. Wall-mounted activation valves shall be located directly adjacent to the shower pattern. It is recommended they have easily removable covers for access to the valve.

      3. Showerhead location.

        Showerheads shall be installed at least 30 inches from walls, preferably near a sink or inside a lab entry door clear of door swing, and 4 inches below ceiling (for ease of routine flushing). Laboratory walls located directly adjacent to safety showers shall be of water/mold-resistant construction (e.g. paperless gypsum board, mold-resistant gypsum board, water-proof coating).

      4. Showerhead placement.

        Showerheads shall be located at least 6 feet away from electrical service (switches, outlets, panels, etc.).

      5. In-line shut-off valve.

        An accessible, identified line shut-off valve shall be provided at or above ceiling within a room or shower location area.

      6. In-line filter screens.

        No screen filters may be installed in the water supply line. Any system-provided screens shall be removed (if installed) upon system installation.

      7. Signage.

        Safety shower signage shall be provided and prominently mounted near showerhead, visible from any direction of approach.

      8. Water temperature.

        Shower water supplied shall be tepid.

      9. Water flow rate.

        Water flow shall be at least 20 gallons per minute (gpm).

      10. Showerhead dripping.

        By design, showerhead dripping shall stop within 1 minute of valve shut-off.

      11. Floor drains prohibition.

        Floor drains are not permitted in laboratories.

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    5. Emergency Eyewash Units

      1. Plumbing requirements.

        Units shall be either directly plumbed or hose type units tied into the cold water plumbing line, installed according to manufacturer’s directions and meeting the requirements of ANSIZ358.1 (most current version). All pipe-plumbed eyewashes shall connect to a sanitary sewer drain. Basin type eyewash units shall have drains sized to continuously drain away supplied water.

      2. In-line shut-off valve.

        Units shall have a standard line shut-off valve (with handle removed) unless line is tapped into a sink cold water line downstream of the shut-off valve.

      3. Eyewash design.

        Unit design shall provide twin stream nozzles to flush both eyes at once, and in a hands-free mode.

      4. Nozzle filters.

        Nozzle heads shall provide easy access to filters, requiring no tools for cleaning or changing when filters are dirty, disintegrated or corroded. Note: Nozzle filters should be installed after initial line flushing to remove contaminants.

      5. Location and positioning.

        Unit shall be securely positioned in place, universally reachable, preferably installed at a sink, at least 6 inches from other equipment, and sufficiently clear of overhead cabinetry or shelving.

      6. Valve activation.

        Unit shall have a non-spring-loaded, easily operated manual activation and shut-off valve.

      7. Water flow rate.

        Water flow for eyewash units only shall be not less than 0.4 gallons per minute for at least 15 minutes. Water flow for units rated for eye/face washing, such as plumbed or hose-type twin stream, shall be not less than 3 gallons per minute for at least 15 minutes.

      8. Water pressure.

        Each eyewash service line shall be provided with an adjustable supply line valve, as noted above, to regulate and control water pressure. The water stream arc should be 6 to 12 inches diameter, depending on unit type and location, and not blocked by any objects.

      9. Nozzle angle.

        Nozzles shall angle forward 30-45° above horizontal for eye and face hose type units, or be so angled forward or toward each other if plumbed bowl units.

      10. Signage.

        Eyewash signage shall be provided and mounted prominently near the eyewash, visible from any angle of approach.

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    6. Flammable Liquids Storage Cabinets

      Flammable liquid storage cabinets shall be provided for laboratories where more than 10 gallons of flammable or combustible liquids are likely to be stored, handled, or used. An appropriate number of cabinets should be provided, of appropriate size, to meet the anticipated needs and allowable load of flammable and combustible liquids for the laboratory fire area.

      1. Labeling and required approvals.

        Installed or provided cabinets shall be properly labeled, and be Underwriters Laboratories (UL), and Factory Mutual (FM) approved.

      2. Retention basin.

        Cabinet shelf must have a retention basin in bottom of cabinet to contain leakages.

      3. Cabinet doors.

        Cabinets shall have positive-latching, self-closing doors.

      4. Cabinet venting.

        1. Un-vented cabinets may be installed/used. However, depending on the types and amounts of chemicals stored, laboratory air quality may be adversely impacted. Vent plugs provided by the manufacturer must be in place in all un-vented cabinets.

        2. Vented cabinets shall be directly vented outdoors in a manner that does not compromise cabinet fire rating and performance and in a manner which does not allow vapors to re-enter the building. c. Manifolding vents of multiple storage cabinets is prohibited.

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    7. Corrosives Storage Cabinets

      1. Cabinet installation.

        Corrosives cabinets meeting criteria in this section shall be provided in sufficient numbers for storage of acids and bases planned for use.

      2. Cabinet materials.

        Cabinets shall be made of non-corroding materials.

      3. Catch pans.

        Cabinets shall have catch pans or tubs to retain liquid spills.

      4. Cabinet labeling.

        Each cabinet shall be individually labeled for storage of either acids or bases (not both).

      5. Cabinet venting (see section V1 - F.4 above)

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    8. Gas Cylinders Storage

      1. Storage area requirements.

        1. Cylinders storage rooms and closets shall be prominently identified as to the type gas contained.

        2. Laboratories using compressed gases having an NFPA health hazard rating of 3 or 4 shall have a continuous mechanically-vented storage area for these gases. Continuous venting shall also be provided for pyrophoric gases and those (other than compressed air) having no physiological warning properties, regardless of health hazard rating.

        3. Programmable oxygen level and toxic gas sensing devices shall be provided for each gas storage and use area as specified by code. These devices shall be capable of alarming to warn area occupants of a gas venting episode, or if the oxygen level in the area is diminished. The warning provided shall be visual and audibly distinguishable, to be heard over other noise sources. Where possible, the alarm should be centrally monitored at a remote location.

      2. Securing of cylinders.

        Laboratory design shall make provision to individually secure all compressed gas cylinders with appropriate restraints located at least 3 feet from the floor. Cylinder connection closets are recommended for compatible compressed gases.

      3. Marking of connectors and lines.

        Where permanent connection hoses and lines are provided for cylinder gases, they shall be marked to identify the gas they contain and the direction of gas flow.

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