Submicron HEPA filters between vacuum traps and fixture valves should be provided to eliminate microorganisms in hazardous areas such as BSL-3 or BSL-4 labs.
Blowout type closets are permitted in the lab side of the airlock for changing rooms in BSL-3 and BSL-4 laboratories.
Aerating stream faucets are not utilized in BSL-3/BSL-4 spaces.
Plumbing Fixtures Serving BSL-3 and BSL-4: Special attention is provided to the selection of plumbing fixtures serving BSL-3 and BSL-4 spaces. Sanitation and resistance to fouling, durability, and prevention of stoppages are of the utmost importance. Fixtures with concealed spaces are not permitted. Lavatories are specified without overflows because of the potential for these concealed spaces to harbor pathogens. Fixtures with integral trap seals (such as water closets) are selected to ensure sufficient trap seal depths, and minimize potential for stoppages. Stainless steel blowout fixtures with 100 mm deep trap seals are available, or manufacturer-modified blowout bowls are utilized as required. Flushometer selection must be appropriate to match the fixture design to ensure proper operation. Water closets and faucets are of the electronic, hands-free type, hard wired and on emergency power. Drinking fountains located outside labs are of the hands-free operation type, utilizing electronic sensors or knee actuation. Indirect waste receptors in labs are constructed of stainless steel or equivalent sanitary, chip-resistant materials compatible with the disinfectant process. All faucets in the lab are actuated by electronic hard-wired and on emergency power sensors, or knee actuation. Foot pedal valves are provided with slow-close valving, are utilized only where selected by the NIH in lieu of electronic or knee actuation, and are arranged to permit ready cleaning behind and under the device. Lab faucets are provided with specially designed vacuum breakers and are served by only the dedicated lab water distribution system.
Except for those in BSL-3 and BSL-4 facilities, backflow preventers are generally not arranged in series because of increased pressure loss. Fire protection backflow preventers are not installed in series. In the case of BSL-4 lab water systems, the use of a break tank shall be considered.
Careful consideration is applied to the design of bio-waste systems serving BSL-3 and BSL-4 facilities. The need for liquid waste decontamination systems, the type of system, consideration of vent filtration, deep seal traps, and selection of piping materials are just a few of the items the A/E must carefully evaluate. The A/E shall work with the designated safety officer during the design of the system and shall comply with NIH/CDC biosafety guidelines. Liquid waste decontamination and HEPA filtration should be provided at all BSL-4 facilities and should be considered as appropriate at the BSL-3 level. Vent filtration may be provided at the BSL-3 level and above.
The A/E must thoroughly evaluate the selection of piping materials for biowaste systems. Appropriate options are indicated in Table F.6 and require careful analysis of chemicals that may enter the system and any potential drainage system sterilization method. Piping serving BSL-4 facilities shall be double-contained and include primary carrier leak monitoring.
Waste systems serving BSL-4 systems are independent systems and are not combined with other building areas. BSL-3 systems should similarly be independent of other areas. Separate waste and vent stacks are provided, and HEPA filtration is of the safe-change (bag-in/bag-out) duplex parallel type and includes hydrophobic filtration.
Fixture traps in BSL-3 and BSL-4 spaces are of the deep seal type, with trap seals not less than 125 mm deep. All drainage systems are designed to minimize stoppages, and waste system velocities of 0.91 m/s are desirable. Trap seals are to be maintained via an appropriate disinfectant chemical fill to prevent cross-contamination, and piping materials shall be thoroughly compatible with program disinfectants. All plumbing fixtures on the lab side of the airlock are routed to decontamination, including water closets and service sinks.
When a BSL-3 suite contains a fume hood, an emergency shower must be provided within the containment area of the suite, preferably within the anteroom area. When a BSL-3 suite does not contain a fume hood, the emergency shower must be within 10 seconds’ reach of the lab occupants. In this case, the emergency shower can be located within the containment area or in the corridor adjacent to the laboratory, provided the lab occupants can reach it within 10 seconds.
For laboratories that are considered biohazard research areas (BSL-3 labs), a parallel HEPA filter system with safe change capability (such as bag-in/bag-out) shall be installed upstream of the vacuum pump in the line from the area. Filtration of air and disinfections of biohazardous materials shall be provided locally by each investigator as required. Lab personnel shall install filtration devices in a manner that will require maintenance when they become loaded. Bypass lines should not be installed. Each investigator should utilize disinfectant traps and filtration at each vacuum inlet. Systems serving BSL-3 labs should not be combined with other lab vacuum systems. Central building vacuum systems should not be utilized in BSL-4 labs. A biohazard warning sign shall be provided at vacuum source equipment from vacuum systems serving biohazard research areas.
Care should be taken not to install reduced-pressure BFP devices in series with one another since they have a significant pressure drop. When the service main enters the building, each water system should tap the main in a parallel arrangement, thereby preventing the need for in-series BFP devices in most NIH facilities. However, in BSL-4 facilities, the laboratory water supply RPBP shall be installed downstream of the incoming domestic water service backflow preventers. A parallel arrangement of RPBPs should be provided, with each device sized appropriately to minimize pressure drop. BSL-3 facilities may be installed in either manner, providing appropriate pressure drop consideration is included and the design is properly justified. Plumbing engineers should be sure to consider the peak pressure drop through BFP devices when designing distribution systems.
In BSL-4 facilities, each water supply system should be isolated with not less than reducedpressure zone type backflow preventers. The engineer should review the application to determine the need for a break tank. In BSL-3 and BSL-4 facilities, the incoming domestic water service backflow preventer should always be installed ahead of the lab system backflow preventer; thus, a series arrangement should be provided. Potable water systems should not penetrate the BSL-4 containment barrier unless independently protected with a reduced-pressure zone device. Laboratory water systems serving BSL-4 laboratories should not serve other building areas. (Read Whole DP&D)