Patent Application
20080278041
The present invention relates to biosafety cabinets, and more particularly to a biosafety cabinet having a cable port to provide means for running cables into the work area by maintaining contamination and clutter control.
A biosafety cabinet is a ventilated cabinet that uses a variety of combinations of air filters, unidirectional air flow, and containment to provide personal, product and cross contamination against particulates or aerosols from bio-hazardous agents. Conventional biosafety cabinets include one or more High Efficiency Particulate Arresting (HEPA) filters, although other types of air filters may be used as well. A HEPA filter is a type of air filter that can remove at least 99.97% of airborne particulates of 0.3 micrometres (μm) in size.
Typically, users need to run small tubing and/or cables inside the cabinet. Examples of such cables include vacuum lines, gas lines, data cables, power cords, and the like. Existing biosafety cabinets allow the tubing and/or cables to enter the cabinet through the cabinet's front work access opening by propping the door conventionally located on the front of the cabinet open and running the tubing and/or cables through the opening. This results in at least partial obstruction of the work area access opening, the potential for cables and tubing leading to the devices inside the work area 112 to be undesirably repositioned by accidental contact from a user, and alteration of the air flow dynamics of the biosafety cabinet due to the tubing and/or cables interfering with airflow at the front edge of the cabinet, among other shortcomings.
In accordance with one embodiment of the present invention, a biological safety cabinet includes a housing formed of a plurality of walls defining a chamber having an internal environment inside the chamber. The walls have a double wall configuration with an interior wall chamber between the walls. A door is disposed on one wall of the housing having an open position and a closed position. The door provides physical access to the chamber when in the open position and obstructs access to the chamber when in the closed position. A cable port is disposed in a wall of the plurality of walls defining the chamber.
The cable port includes an opening through the double wall structure that leads from an external environment through the wall chamber to the internal environment. The cable port also includes an outer flexible membrane disposed on an outside wall of the double wall structure of the housing that covers the opening and an inner flexible membrane disposed on an inside wall of the double wall structure of the housing that covers the opening. The cable port further includes at least one slit disposed in the outer flexible membrane that is configured to permit a cable to pass through the slit and the outer flexible membrane and at least one slit disposed in the inner flexible membrane that is configured to permit a cable to pass through the slit and the inner flexible membrane. The cable port substantially occludes airflow from the internal environment through to the external environment.
In accordance with various aspects of the present invention, the double wall configuration of the biosafety cabinet maintains a negative pressure air space in the wall chamber between the inner and outer wall of the double wall configuration when the cabinet is in operation.
In accordance with variations of the present invention, the biological safety cabinet includes a first ring that is disposed on the outer flexible membrane to tightly attach the outer flexible membrane to the double wall structure and a second ring that is disposed on the inner flexible membrane to tightly attach the inner flexible membrane to the double wall structure.
In accordance with various aspects of the present invention, a cable port plug is provided to cover the cable port when the cable port is not in use. A plurality of cable hooks are provided inside of the cabinet, disposed on one or more walls of the chamber. The cable hooks carry a plurality of cables.
In accordance with variations in the embodiments of the present invention, the door of the airflow bypass system may be slidably mounted within the housing. The door includes a visibility screen. The biological safety cabinet may further include a germicidal light source that generates germicidal light in the internal environment of the chamber.
In accordance with aspects of the present invention, a method of controlling contamination includes providing a biological safety cabinet and providing a cable port gasket mounted on the cable port. The cable port gasket keeps air particulates from entering the chamber. The method also includes providing a cable port plug and covering the cable port with the cable port plug when the cable port is not in use, wherein the cable port plug keeps air particulates from entering the cable port and the chamber.
The present invention will become better understood with reference to the following description and accompanying drawings, wherein:
An illustrative embodiment of the present invention relates to a biosafety cabinet having cable ports disposed in walls of the cabinet that allow small tubing and/or cables to enter the cabinet through the walls, eliminating problems associated with running the tubing and/or cables through an open door at the front of the cabinet. The cable ports enable the user to fully close the view screen door, while maintaining the ability to connect various tubes and/or cables and the like to devices in the interior work area of the cabinet. In accordance with one embodiment of the present invention, the biosafety cabinet has a double wall configuration with negative pressure air space between the two walls. Any contamination attempting to escape from the cabinet into the room or enter the cabinet from the outside environment is captured in the negative pressure area between the walls and transported directly to an air filter. This ensures containment of internal hazards (personal protection) as well as product protection from outside contaminants.
Prior to discussing the details of the invention, a brief overview of the different biosafety cabinets will be provided. A biological safety cabinet is designed to reduce the potential escape of airborne research or experimental materials and byproducts into the worker's environment and to remove contaminants from air entering the research work zone. A laminar flow biological safety cabinet is designed to provide three basic types of protection: personal protection from harmful agents inside the cabinet, product protection to avoid contamination of the work, experiment or process, and environmental protection from contaminants contained within the cabinet. In addition, the cabinet will provide cross contamination protection in the work zone to prevent airborne particulates from traveling from one side of the cabinet to the other side of the cabinet.
Over the years, the scientific community has adopted commonly accepted classification criteria to differentiate containment capabilities and performance attributes of biological safety cabinets. In general, biological safety cabinets are divided into 3 classifications as illustrated in Table 1.
Biosafety Level 1 encompasses practices, safety equipment and facilities appropriate for work with defined and characterized strains of viable microorganisms not known to cause disease in healthy adult humans. Work is generally conducted on open bench tops using standard microbiological practices. For biosafety level 1, special containment equipment or facility design is neither required nor generally used.
Biosafety Level 2 encompasses practices, safety equipment and facilities appropriate for work done with a broad spectrum of indigenous moderate-risk agents present in the community and associated with human disease in varying severity. It differs from biosafety level 1 in that laboratory personnel have specific training in handling pathogenic agents and are directed by competent scientists; access to the laboratory is limited when work is being conducted; extreme precautions are taken with contaminated sharp items; and certain procedures in which infectious aerosols or splashes may be created are conducted in biosafety cabinets or other physical containment equipment. A Class I or Class II biosafety cabinet is recommended for work involving these agents.
Biosafety Level 3 encompasses practices, safety equipment and facilities appropriate for work done with indigenous or exotic agents with a potential for respiratory transmission that may cause serious and potentially lethal infection. More emphasis is placed on primary and secondary barriers to protect personnel in the contagious area, the community, and the environment from exposure to potentially infectious aerosols. A Class I or Class II biosafety cabinet is required for work involving these agents.
Biosafety Level 4 encompasses practices, safety equipment and facilities appropriate for work done with dangerous and exotic agents that pose a high risk of life threatening disease. Agents may be transmitted via the aerosol route, and for which there is no available vaccine or therapy. Access to the laboratory is strictly controlled by the laboratory director. The facility is either in a separate building or in a controlled area within a building, which is completely isolated from all other areas of the building. A Class III biosafety cabinet or pressurized environmental suit is required for work involving these agents.
The Class I cabinet has the most basic and rudimentary design of all biosafety cabinets. A stream of inward air moving into the cabinet contains aerosols generated during microbiological manipulations. It then passes through a filtration system that traps all airborne particulates and contaminants. Finally, clean, filtered air is exhausted from the cabinet. The filtration system usually consists of a pre-filter and a HEPA (High Efficiency Particulate Air) filter.
Although the Class I cabinet protects the operator and the environment from exposure to biohazards, it does not prevent samples being handled in the cabinet from coming into contact with airborne contaminants that may be present in room air. Naturally, there is a possibility of cross-contamination that may affect experimental consistency. Class I biosafety cabinets are suitable for work with microbiological agents assigned to biological safety levels 1, 2 and 3.
Like Class I biosafety cabinets, Class II biosafety cabinets have a stream of inward air moving into the cabinet. This is known as the inflow and it prevents the aerosol generated during microbiological manipulations to escape through the front opening. However, unlike Class I cabinets, the inflow on Class II cabinets flows through the front inlet grille, near the operator. None of the unfiltered inflow air enters the work zone of the cabinet, so the product inside the work zone is not contaminated by the outside air.
A feature unique to Class II cabinets is a vertical laminar (unidirectional) HEPA-filtered air stream that descends downward from the interior of the cabinet. This continuously flushes the cabinet interior of airborne contaminants and protects samples being handled within the cabinet from contamination and is known as the down flow. Some cabinets may exhaust air directly back to the laboratory, while others may exhaust air through a dedicated ductwork system to the external environment.
Class II cabinets, like Class I cabinets, protect both the operator and environment from exposure to biohazards. In addition, Class II cabinets also protect product samples from contamination during microbiological manipulations within the cabinet interior and are all suitable for work with agents assigned to biological safety levels 1, 2 and 3. Class II cabinets are further classified according to how they exhaust air.
The Class II Type A biosafety cabinets exhaust air directly back to the laboratory, and they may contain positive pressure contaminated plenums. When toxic chemicals must be employed as an adjunct to microbiological processes, these cabinets are not used. Exhaust HEPA filtration only removes airborne aerosols including biohazards, and not chemical fumes.
The main difference between Class II type A and type B cabinets is that the type B cabinets must be operated with an external blower and it exhausts air to the external environment via a dedicated ductwork system. Without the external blower, the cabinet's internal blower will blow the air (and microbiological agents) inside the work zone through the front operator, towards the operators face, creating a dangerous situation.
The Class II Type B1 biosafety cabinets have a dedicated exhaust feature that eliminates re-circulation when work is performed towards the back within the interior of the cabinet.
In the Class II Type B2 cabinet all inflow and down flow air is exhausted after HEPA filtration to the external environment without recirculation within the cabinet. Type B2 cabinets are suitable for work with toxic chemicals employed as an adjunct to microbiological processes since no re-circulation occurs.
The Class III biosafety cabinet provides an absolute level of safety, which cannot be attained with Class I and Class II cabinets. Class III cabinets are usually of welded metal construction and are designed to be gastight. Work is performed through glove ports in the front of the cabinet. During routine operation, negative pressure relative to the ambient environment is maintained within the cabinet. This provides an additional fail-safe mechanism in case physical containment is compromised.
On Class III cabinets, a supply of HEPA filtered air provides product protection and prevents cross contamination of samples. Double HEPA filtered exhaust air may be incinerated. Class III cabinets exhaust air via a dedicated ductwork system to the external environment. When a dedicated ductwork system is employed, they are also suitable for work employing toxic chemicals as an adjunct to microbiological processes. Class III biosafety cabinets are frequently specified for work involving the most lethal biological hazards.
Now turning to the present invention,
Continuing with the cable port 108 discussion, an inner wall hole 214 is cut in an inner wall 202 and a second outer wall hole 212 is cut in the outer wall 204. The inner and outer wall holes 212 and 214 may be concentric and may be, for example, of about a 3″ diameter, or another dimension based on the intended use of the cable port 108. The inner wall hole 214 has a cable port gasket 206 and a ring 208 mounted over the inner wall hole 214. The gasket 206 and the ring 208 may be mounted using, for example, a combination 210 of weld studs, a flat washer, lock washer and wing nut, or other known methods for mounting gaskets and rings similarly situated. The gasket 206 and the ring 208 are located in the interior air space between the inner wall 202 and the outer wall 204.
Similar to the inner wall hole 214, the outer wall hole 212 cut in the outer wall 204 has a cable port gasket 232 and a ring 238 mounted over the hole 212. The gasket 232 and the ring 238 may be mounted using, for example, a combination 242 of weld studs, a flat washer, lock washer and wing nut, or other known methods for mounting gaskets and rings similarly situated. The gasket 232 and the ring 238 are located in the interior air space between the inner wall 202 and the outer wall 204.
One ordinary skill in the art will appreciate that the outer cable port gasket 232 used in the outer wall 204 of the biosafety cabinet 100 may have the same structure as the inner cable port gasket 206. A hole 248 with a slit 244 is located in the center of a membrane 236 (outer membrane) extending across the outer cable port gasket 232 to permit the passing of small tubing, power, and/or data cables, and the like, into the work area 112 of the biosafety cabinet 100. The outer gasket 232 has a larger outer diameter than the diameter of the outer wall hole 212 cut in the outer wall 204.
One of ordinary skill in the art will appreciate that the outer ring 238 used in the outer wall 204 of the biosafety cabinet 100 may have the same structure as the inner ring 208 used in the inner wall 202 of the biosafety cabinet 100. The outer cable port ring 238 along with the hardware combination 242 holds the outer gasket 232 tightly around its perimeter to the outer wall hole 212. This arrangement prevents air from entering through the perimeter of the outer gasket 232. The outer gasket 232 has small holes 234 positioned closer to the outer diameter of the outer gasket 232. The holes 234 of the outer gasket 232 correspond to the holes 240 of the outer ring 238 to provide access to the combination 242 of weld studs, a flat washer, lock washer and wing nut.
The negative pressure air space between the inner 202 and outer wall 204 captures particulates 201 in the air that may be attempting to migrate between the two gasket openings when small tubing and/or cables are running through them. The cable port gasket 206, 232 may be made of a soft, flexible material, such as neoprene, that allows the gasket 206, 232 to better surround the small tubing and/or cables running through the gasket 206, 232, thus preventing most air particulates 201 from passing through the gasket 206, 232. As a result, the biosafety cabinet 100 maintains its integrity and contamination control. The material of the gasket 206, 232 needs to form a snug fit around the small tubing and/or cables running through the gasket 206, 232. The main purpose is to create as much of an airtight seal as possible around the small tubing and/or cables. The aperture of the slit 222, 244 located in the center of a membrane 230, 236 extending across the cable port gasket 206, 232 may be designed to fit around a special designed cable, such as a cable with a star, cross, triangular, square or Y-shaped cross-section. Similarly, the width of the slit 222, 244 may be designed according to the shape and number of the small tubing and/or cables that will be run through it. The slit 222, 244 may also have a straight line, a curved line, a wave pattern or a broken line aperture.
When a cable port 108 is not in use, a cable port plug assembly 300 is provided to cover and occlude both openings in the cable port. In accordance with one embodiment, the cable port plug assembly 300 can be installed without the need for tools.
Cable hooks 400 may be installed inside the cabinet work area 112 to keep small tubing and/or cables off the work area 112, and also to support the tubing and/or cables to reduce the amount they may pull on the cable port 108, which could otherwise impact the ability of the cable port 108 to seal around the tubing and/or cables.
In operation, a user makes use of the cable port 108 to provide tubes, cables, cords, power, or other items to the interior work area 112 of the biosafety cabinet 100 on an as needed basis. The use of the cable port 108 provides an alternative to simply running such items through the lower opening of a door 106 in the view screen 104 area. If the cable port plug assembly 300 is in place, the assembly 300 is first removed to provide access the cable port 108. A user can then pass the desired tubing, cable, and the like through the cable port from either inside the cabinet or outside the cabinet and make any desired connections with devices in the work area 112, and/or with devices or sources outside of the biosafety cabinet 100.
With the cables 502 and tubes 504 running through the cable port 108, the slit 222, 244 and the hole 220, 248 provide the membrane 230, 236 with an improved ability to seal around the cables 502 and tubes 504. A cable hook 400 is provided in the cabinet to keep the cables 502 and tubes 504 away from the work area. When the cabinet 100 is in use, there is a negative air pressure maintained within an internal wall chamber 250 between the inner wall 202 and the outer wall 204. The negative air pressure draws air in the direction of arrows A and B from outside of the biosafety cabinet 100 (arrow A) and from the interior work area 112 (arrow B) and then down to a filter location (not shown) to filter the air.
Numerous modifications and alternative embodiments of the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure may vary substantially without departing from the spirit of the invention, and exclusive use of all modifications that come within the scope of the appended claims is reserved.
This application claims priority to, and the benefit of, co-pending U.S. Provisional Application No. 60/928,510, filed May 10, 2007, for all subject matter common to both applications. The disclosure of said provisional application is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60928510 | May 2007 | US |
