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US 5,295,902 AGranted
Biological safety cabinet
AssigneeForma Scientific, Inc.
InventorKuah T. Hock
Life of this patent
Estimating the term…
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AssigneeForma Scientific, Inc.
InventorKuah T. Hock
Estimating the term…
A biological safety cabinet comprising an enclosure having two side walls, a rear wall, a bottom wall defining a work surface, a top wall and a front window, below which access can be had to the work surface, the enclosure defining a work area. A plenum surrounds the enclosure and communicates with the work area. A blower induces a negative pressure within the plenum to circulate contaminated air through a filter within the enclosure, which creates a downwardly directed air curtain of work area air below the window. A vertically oriented outwardly facing channel section is secured to each side wall adjacent the window. Each channel section has a downwardly and forwardly sloping upper end, a rear edge of which extends above a lower edge of the window and a front edge of which extends below the lower edge of the window. The plenum communicates with each channel. Ambient air and air within the air curtain adjacent upper lateral edges of the air curtain are accelerated downwardly by the channels to reduce the tendency of the ambient air and the cabinet side walls to decrease the velocity of the air curtain, thereby strengthening the air curtain and reducing a tendency of the ambient air and the work area air to interchange.
A biological safety cabinet comprising:
The biological safety cabinet of claim i wherein said channel has an inside depth dimension of between about 0.5 inches and about 0.6 inches.
A biological safety cabinet comprising:
A biological safety cabinet comprising:
A biological safety cabinet comprising:
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Using chambers or hoods covering the area: fume cabinets or cupboards, e.g. for laboratories
Means for sterilizing, maintaining sterile conditions or avoiding chemical or biological contamination
By purification, e.g. by filtering; by sterilisation; by ozonisation: clean air work stations, i.e. selected areas within a space which filtered…
Preventing escape of dirt or fumes from the area where they are produced; Collecting or removing dirt or fumes from that area: with the assistance…
Term ended 7 May 2012 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This invention relates generally to biological safety cabinets, and more particularly to a biological safety cabinet having an improved air flow scheme which reduces the interchange of ambient air external to the cabinet with work area air internal to the cabinet.
Biological safety cabinets currently in use have a bottom defining a work surface, a top, three sides, and a transparent front window partially covering the front of the cabinet. The cabinets are used as workbenches for biological cell culturing. Within the cabinet contaminate air is circulated through a filter downwardly through the work area onto the work surface, which work area air, after becoming contaminated, is pulled through a plenum, which surrounds a portion of the cabinet, by a blower and forced downwardly back through the filter again. A high efficiency particulate air ("HEPA") filter is generally employed to filter the air.
The window which covers a portion of the front of the cabinet is transparent to allow for viewing the contents of the work area. There is a 10 inch opening between the lower edge of the window and the threshold of the cabinet to allow for insertion of a user's arms and hands and equipment into the cabinet for placing media into, feeding and examining cell cultures on the work surface and other tasks.
FIG. 1 is a front plan view of the biological safety cabinet of the present invention;
FIG. 2 is a side plan view of the cabinet of FIG. 1;
FIG. 3 is a perspective view of a lateral front side of the cabinet of FIG. 1, greatly enlarged, illustrating the channel section, grill and window and their effects on the air flow;
With reference to FIGS. 1 and 2, there is illustrated a biological safety cabinet i. The cabinet 1 includes two side walls 5 and 6, a rear wall 7, a bottom wall 8 defining a work surface, an air diffuser forming a top wall 9 and a front window 10. The side walls, rear wall, bottom and top walls and front window define an enclosure or work area 12. A plenum 15 surrounds the side walls 5 and 6, rear wall 7 and bottom wall 8 of the cabinet
A blower 16 powered by a motor 17 creates a negative pressure within the plenum 15 and forces air through a high efficiency particulate air ("HEPA") filter 18 located above air diffuser or top wall 9. There is an exhaust filter at 19 and an exhaust filter guard at 20. A control panel 21 is provided for controlling operation of the cabinet 1.
With reference to FIG. 2, the flow pattern within the safety cabinet 1 is illustrated. Negative pressure contaminated air NPCA is drawn through the plenum 15 upwardly to the blower 16. The negative pressure contaminated air NPCA continues upwardly through blower 16. Positive pressure contaminated air PPCA travels upwardly through exhaust filter 19 and downwardly through HEPA filter 18. Filtered air FA passes downwardly into the work area 12 as work area air where it becomes contaminated from the products internal to the work area 12. The work area air WAA is drawn into the plenum 15 through slots 47 in the sidewalls 5 and 6 (FIG. 3), through threshold 26 and through channel sections 25, the operation of which will be subsequently described. Ambient air AA enters the channel sections 25 as well as threshold 26 of cabinet 1 and is drawn into plenum 15.