GB2181967A

GB2181967A - Filter unit

Info

Publication number: GB2181967A
Application number: GB08524367A
Authority: GB
Inventors: Malcolm Irving Mcnaughton; Brian Walker
Original assignee: Walker Filtration Ltd; BOC Healthcare Inc
Current assignee: Walker Filtration Ltd; Datex Ohmeda Inc
Priority date: 1985-10-02
Filing date: 1985-10-02
Publication date: 1987-05-07
Also published as: GB8524367D0; GB2181967B

Abstract

A disposable filter unit 1 includes a transparent housing 2 in which is located a filter element 8. The inlet 4 and preferably, also the outlet 6 of the container 2 have associated with them non-return valves 18, 20. The filter unit 1 can be used as the first stage filter in apparatus for removing noxious fumes from a working area, such as an operating theatre where laser surgery is performed. A second stage filter is located between unit 1 and a suction pump. Both filters include mechanical filtering layers followed by a sheet of active carbon. <IMAGE>

Description

SPECIFICATION Scavenging and filtration apparatus The present invention relates to filter units and in particular to disposable filter units adapted to form part of apparatus for the scavenging and filtration of noxious and/or toxic fumes created at a work location. For example, lasers have several surgical and medical uses. They can be used in eye retina correction, excising or vaporising both benign and malignant tumours, various applications in neuro-surgery, gynaecology and ear, nose and throat surgery. However, the ever present byproduct of laser surgery is the smoke and nauseating odour of vaporised tissue. This smoke and the viable cells and micro-organisms contained within it presents a health hazard to the surgeon and the surgical team.As a consequence, the smoke, odour and particulate matter produced during laser surgery have severely inhibited the performance of many operating room personnel. The fumes created by such surgical operations include a lot of smoke which often screens the patient from the surgeon and reduces the speed with which the surgeon can operate and frequent blockage of the centralised hospital vacuum system has been experienced.

It is an aim of the present invention to provide an apparatus which will scavenge the fumes created at a working area particularly an operating theatre in which laser surgery has to be performed, and filter said fumes so that the working enviroment is safe and not unpleasant to work in.

It is a further aim of the present invention to provide a disposable filter unit for use with such an apparatus.

For the avoidance of doubt the expression "toxic and noxious fumes" is intended to include smoke, vaporised tissue or other material which have unpleasant odours and particulate solid bodies which are formed during laser surgery.

According to one aspect of the present invention, a disposable filter unit comprises a container having an inlet for fluid to be filtered and an outlet for filtered fluid, a filter element located within the container between said inlet and said outlet, and a non-return valve, associated with the inlet and biased towards its closed position.

Preferably, a further non-return valve is associated with the outlet and biased towards its closed position.

According to a further aspect of the present invention a fluid scavenging and filtration apparatus comprises a housing, a disposable first stage filter unit as defined above releasably mounted on the housing and arranged in series with a second stage filter unit located within the housing.

An embodiment of the invention will now be described, by way of example, reference being made to Figures of the accommpanying drawings in which: Figure 1 is a partial longitudinal cross-section through a disposable filter unit; Figure 2 is a fragmented cross-section on line 2-2 of Figure 1; Figure 3 is a perspective view of an apparatus for the scavenging and filtration of fluids including the disposable filter unit of Figure 1; Figure 4 is a rear view of the apparatus of Figure 3; Figure 5 is a fragmented cross-section of the disposable filter unit of Figure 1 releasably engaged with a second stage filter unit forming part of the apparatus of Figures 3 and 4; and Figure 6 is a modified schematic side view of the apparatus of Figures 3 and 4.

Referring first to Figure 1, this shows a disposable filter unit 1 which includes a container 2 of plastics material at least a portion of which is transparent or translucent. The container 2 is generally cylindrical and includes an inlet 4 for fluid to be filtered and an outlet 6 for filtered fluid. Located within container 2 between the inlet 4 and the outlet 6 is a filter element 8. The filter element 8 is sealed within the container 2 and designed to direct fluid to be filtered through the element from outside to within (see arrows A). This flow direction not only utilises the greatest surface area of the element 8 but also discolouration of the element can be seen through the plastics container 2.Referring also to Figure 2 filter element 8 includes an outer cylindrical sheet 9 of micro-porous material embodying a layer of borosilicate glass fibres and an inner cylindrical sheet 10 of activated carbon paper.

The micro-porous material has an efficiency of at least 75% when filtering particles of 0.6 micron mean diameter. As shown, both sheets 9, 10 are formed with pleats over their entire area and are supported by opposed end members 14, 16. The end member 16 is a fluid tight fit within the container 2 but has a port 17 for the passage of filtered fluid through the filter element 8 as will be explained.

Associated with both the inlet 4 and the outlet 6 are spring loaded non-return valves 18, 20. Spring 22 of non-return valve 18 bears at one end against the end member 14 and biases the valve head 23 to a closed position against a seating 24 formed in the inlet 4. 8pring 25 is positioned between a shoulder 26 formed in the outlet 6 and a valve head 27 which it biases to close the port 17.

In use, a vacuum is applied to the outlet 6 which will open the non-return valves 18, 20 against the bias of their respective springs 22 and 25 thereby allowing fluid to be filtered to enter the inlet 4 and flow in the direction of the arrows A through the filter element 8 and out via port 17 and outlet 6.

Referring also to Figures 3 to 6 the filter unit 1 is releasably mounted on a housing 30 by means of a spring clip 32 such that outlet 6 is slidably received, in a fluid tight manner, in an inlet 34 of a second stage filter unit 36 located within the housing 30. The exact arrangement of the coupling between the first and second stage filter units 1, 36 is illustrated slightly differently in Figures 5 and 6 in that in Figure 6 an adaptor 50 interconnects the inlet 34 and the outlet 6. An outlet 38 of the unit 36 is in communication via pipe 37 with the vacuum side of a vacuum pump 39.

The pressure side of the vacuum pump 39 communicates with an outlet 42 from the housing 30.

The vacuum pump 39 may also incorporate an impeller (not shown) which draws ambient air, for cooling purposes, through a grill 44 at the rear of the housing 30 over the pump and out via louvres (not shown).

In use, with the vacuum pump 39 in operation, suction will open the non-return valves 18, 20 in the first stage filter unit 1 so that fluid to be scavenged and filtered enters the inlet 4 passes through the filter unit 1 and exits via outlet 6 into the inlet 34 of the second stage filter unit 36 then out through outlet 38, pipe 37 and vacuum pump 39 to be released as relatively clean fluid to atmosphere at outlet 42.

It will be evident to those skilled in the art that a flexible pipe can be coupled to the inlet 4 and a suction head located at the point where the toxic and noxious fumes are being created.

In the event that the apparatus described above is being used to scavenge and filter noxious fumes created during laser surgery the second stage filter unit 36 includes a filter element having an outer cylindrical sheet of activated carbon and an inner cylindrical sheet of material which acts as a bacterial filter both inner and outer sheets being pleated over their entire area. It is believed that more than 75 percent of noxious fumes and particulate debris are removed by the first stage filter unit 1 which needs to be replaced during normal usage once a week. The second stage filter unit 36 removes substantially all of the remainder of the noxious fumes, bacteria and the remaining particulate debris and need only be removed from the housing 30 approximately once every three months.

It will be evident that when the vacuum pump 39 is de-activated, then the non-return valves 18, 20 will return to their closed positions thus enabling the contents of the filter unit 1 to be isolated from the working environment when the apparatus is not in use and during detachment from the housing 30.

A pressure gauge 46 is incorporated to indicate the pressure of fluid flowing through the filter units 1, 36 to give an indication when one or other of the filter units needs to be replaced. A further check on the level of contamination of the filter unit 1 is the fact that filter element 8 can be observed through the transparent or translucent container 2. The apparatus described above can be mounted as a mobile unit on a trolley for movement about an operating theatre or other work area in which case it is rendered anti-static.

Alternatively the apparatus could be permanently fixed in, for example, an operating theatre.

It will be apparent that modificiations can be made to the apparatus. For example the nonreturn valves 18, 20 as described could be replaced by single piece valves known in the art as "umbrellas" or "duckbills" which combine spring action and valve head components. It is also possible to include an inlet valve on the second stage filter unit 36 which will open when the first stage filter unit 1 is inserted and close when the first stage filter unit is removed for replacement. Thus any bacteria held in the second stage filter unit 36 would be prevented from entering the atmosphere when replacing a first stage filter unit 1.

Further, the outlet 42 which is screwed directly into the vacuum pump 39 can be provided with activated carbon so that it acts as a final filter and also a silencer for the vacuum pump.

Although reference has been made in the embodiment described hereinbefore to the scavenging and filtration of the toxic and noxious fumes created during laser surgery, the apparatus described cold be used to scavenge and filter other types of fumes created at a work location in which case the material of the filter elements would be altered, if necessary, to filter more efficiently the fumes being created. For example, other micro-porous materials used might include plastics membranes with finite pore sizes.

Claims

1. A disposable filter unit comprising a container having an inlet for fluid to be filtered and an outlet for filtered fluid, a filter element located within the container between said inlet and said outlet, and a non-return valve, associated with the inlet and biased towards its closed position.

2. A disposable filter unit as claimed in Claim 1, in which a further non-return valve is associated with the outlet and biased towards its closed position.

3. A disposable filter unit as claimed in Claim 1 or 2, in which the filter element includes a cylindrical sheet of micro-porous material having an efficiency of at least 75% when filtering particles of 0.6 micron mean diamter.

4. A disposable filter unit as claimed in Claim 3, in which the micro-porous material is glass micro-fibre.

5. A disposable filter unit as claimed in Claim 3, in which the micro-porous material is a plastics membrane.

6. A disposable filter unit as claimed in Claim 3, 4 or 5 in which the cylindrical sheet is pleated over its entire area.

7. A disposable filter unit as claimed in Claim 6, in which said cylindrical sheet forms an outer layer of the filter element, with a correspondingly pleated activated carbon paper forming an inner layer.

8. A disposable filter unit as claimed in any one of Claims 1 to 7, in which at least a portion of the container is transparent or translucent for observing the condition of the filter element.

9. A fluid scavenging and filtration apparatus comprising a housing, a disposable first stage filter unit as claimed in any one of Claims 1 to 8 releasably mounted on the housing and arranged in series with a second stage filter unit located within the housing.

10. An apparatus as claimed in Claim 9, in which the outlet of the first stage filter unit is slidably received, in a fluid tight manner, in an inlet of the second stage filter unit, and an outlet of the second stage filter unit being in communication with a vacuum source, the arrangement being such that when the vacuum source is activated the or each non-return valve is moved from its closed position to an open position thereby permitting fluid to pass through the first and second stage filter units in series.

11. An apparatus as claimed in Claim 10, in which the vacuum source is a pump, the vacuum side of which is connected to the outlet of the second stage filter unit and the pressure side of which is connected to a third stage filter unit.

12. An apparatus as claimed in any one of Claims 9 to 11, in which the second stage filter unit includes a filter element having an outer cylindrical sheet of activated carbon and an inner cylindrical sheet of material which acts as a bacterial filter both inner and outer sheets being pleated over their entire area.

13. An Apparatus as claimed in any one of Claims 9 to 12, in which a pressure gauge is mounted on the housing to measure and indicate pressure buiid-up in the first and second stage filter units due to contamination.

14. An apparatus as claimed in any one of Claims 9 to 13, in which the housing is mounted for movement about a work area on a trolley.

15. An apparatus as claimed in any one of Claims 9 to 14, in which the apparatus is antistatic for use in hospital operating theatres.

16. A disposable filter unit constructed and arranged substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 of the accompanying drawings.

17. A fluid scavenging and filtration apparatus constructed and arranged substantially as hereinbefore described, with reference to and as illustrated in, the Figures of the accompanying drawings.