GB2178772A - Inflatable tent with fan and filter - Google Patents

Abstract

An inflatable tent intended primarily for medical or surgical use consisting of flexible plastics sheeting 6 and provided with a fan for inflating the tent a filter for filtering the air entering the tent and a release valve 8 having an aperture the size of which can be varied preferably both from within or outside of the tent. <IMAGE>

Description

SPECIFICATION Improvements in or relating to inflatable tents This invention relates to an inflatabletentthat isto say to a structure usually ofa temporary nature which is maintained in an erected condition by maintaining the air pressure within it at a super atmospheric pressure. Such tents are generally made from flexible plastics orfilms or sheets oftextilefabric either laminated or impregnated with synthetic resins to render them substantially airtight. Tents of this kind can vary greatly in size and they are used for a great variety of different purposes, for example warehouses, sports rooms etc.

The structures are maintained inflated by fans which operate continuously, and air release valves are employed to allow any excess air entering the structure to vent to the atmosphere.

The control of the airflow for many forms of structures is not especially critical beyond ensuring that the structure remains inflated when it is to be used for the purposes indicated above. However different situation is presented when the structure is to be used for certain highlyspecialised purposesforexample for medical purposes in the treatment of burns or infectious diseases orthe manufacture of microelectronic components orfor animal or plant breeding purposes. In such cases air present in the structure has to comply with high standards of sterility or purity for example it should not contain more than five viable organisms pew cubic metre of air.Preferably the conditions should comply with the requirements of British Standard Specification No. 5295 which re quires that the particle count depending on the parti cularclass ofspecification which isto applyshould be within the range of 3,000-200,000 particles per cubic metre and the particle size should be in the range of 0.5-25 microns.

In order to ach ieve these requ i rements we have tried attaching a prefilter pad to the inlet of the fan and a final filter sold underthe trade mark HEPAto the outletofthefan used for inflating the structure.

However we found that in orderto maintain the tent in a satisfactory, inflated condition it was necessary to maintain a pressure within the tent of about 5to 20 mm of water as measured on a water gauge. Further in orderto maintain this pressure the fan had to operate at a rate which conflicted with the capacity ofthe filterto reducethe particle countto the level required by the above mentioned British Standard Specification. Attempts to achieve the desired balance between the particle count and the correct inflation pressure by adjustment of the operating speed of the fan did not always result in the results desired. We have now found that the correct balance can be obtained much more reliably ifthe structure is provided with a release valve having a variable aperture.

Accordingly this invention provides an inflatable tent having flexible air impermeable walls orwall sections a fan provided with a filterfor inflating the tent with filtered air and a release valve having an aperture the size of which can be varied.

This invention is illustrated but not restricted by the following drawings in which: Figure 1 is a view in perspective of one form of invention tent Figure2 is a side view taken in vertical section ofthe valve shown as member (8) of Figure 1 Figure3 is a front view of the valve shown in Figure 2.

In Figure 1 the tent is provided with four upright supports (1 ) which are connected to a solid floor (2) made preferably of hard wearing non slip plastics material. Four upper members (3) are joined together to form a support frame which is connected slidably to the uprights (1). Afan (4) for inflating thetent incorporates a prefilterpad and a final filter sold underthe trade mark HEPA. Thefan is secured to two cross members (5) which are themselves secured to the support members (3). The walls (6) ofthetent which are made conveniently of lighttransparent polyvinyl plastics film are constrained bythefloor(2) the uprights (1) and the upperslidable structure defined by members (3) and (5). Additional anchorage is provided by loops (16).The walls are provided with three openings, the first consisting of a doorflap (7) having a substantially airtight heavy duty double sided zipfasteneras a meansforopening and closing the door. The second aperture consists in a release valve (8) having apertures the sizes of which can be varied. The third opening is provided by a sleeve in the wall of the tent which fits onto the outletfilter attached to fan (4).

The release valve (8) shown in greater detail in Figures 2 and 3 consists of two apertured discs which are able rotate relative to one another about a common shaft (11 1 A knurled knob (12 and 13) is attached to each disc and the valve is secured by adhesive or heat welding to the shoulders of a cutout portion of the wall (6) of the tent. An operative can by turning either of the two knobs (12 and 13) bring the apertures (14 and 15) in the discs into varying degrees of register and in this way he can control accurately the rate of escape of air and thus the pressurewithin thetent. In addition the presence of a knob on opposing sides of the valve enables the valve to be operated both from inside or outside the tent.

The presenttents incorporate preferably a frame which is a lightweight knockdown orcollapsable structure which can be taken apart or collapsed for example by folding ortelescopic movementforstorage ortransportation and can be erected for use by appropriate assembly or by reversal of the collapsing procedure.

Frame members particularly for smaller sizes of tents for example those having wall lengths of two to three metres can be made by assembling sections of frame members each consisting of a metal tube having a swaged end so that two or more sections can be joined together by means of a push fit joint so as to obtain a frame member of the desired length. The sections can also be connected together by a spring so that when they are not assembled together to form a membertheyare less likelyto become separated and lost. However when the sections are assembled the springs assist in maintaining the push fitjoint intact.

In orderto erectthetenttheframe is firstassem- bled and the tent walls are then unfolded within the frame structure so that the floor or base covers the entire area ofthefloorcovered by the frame. The fanfiltercombination is then inserted into the sleeve and plugged into the electrical supply care being taken to ensure that the doorflap (7) and valve (8) are closed. When the fan is switched on the tent walls inflate within the frame and causes the fan/filter com- bination (4)andsupportframe(3)to risetotheposi- tion shown in Figure 1.At this stage valve (8) is opened and by varying the sizes of the apertures and the speed of the fan the tent can be maintained correctly inflated whilst ensuring that the airwithin the tent complies with the requirements of British Standard Specification No. 5295.

Tents made according to the present invention can be varied in different ways. Firstly it is to be appreciated structures fall within the scope of the invention which ordinarily may not be regarded astents. Furthermore whilstthe presence of a frame is preferred a frame is not essential, since hemispherical or hemicylindrical tents without frames are also envisaged. A further modification involves the provision of an extra opening or openings in the wall ofthe tent supplemented with a suitable air lock to permit articles such as food or instruments to be passed in or out of the tent without causing any serious deflation.

The tent can also be attached to a compartment such as an ante-room having rigid walls in which case the door into the tent and the fan andfilterorthe outlethavingthevariableaperturecan beincorporated with the wall which is common to both the tent and the ante-room. In this arrangementthe common wall is preferably one ofthe rigid walls of the ante- room and which therefore replaces one of the flexible walls of the tent.

The tents are erected generally on the floor of a building. Howeverthey can also be assembled in a vehicle of appropriate size thereby making available treatment rooms which can not only be erected very quickly but also to be moved rapidly from one locality to another. Fans are generally used for inflating the tent. However any convenientform of deviceforforc- ing air into the tent can be used and the-term "fan" is to be interpreted accordingly.

Claims (10)

1. An inflatable tent having flexible air im perme- ablewailsafan provided with afilterforinflatingthe tent with filtered air and a release valve having an aperture the size of which can be varied.

2. A tent according to Claim 1 wherein the release valve comprises two apertured discs which are rot- able relatively to each otherabouta common shafts

3. AtentaccordingtoeitherofClaims1 and2 wherein the release valve is provided with operating mea ns whereby the vatve can be operated both from within and outside of the tent.

4. Atentaccording to any one ofthe preceding claims wherein thetent is providedwith a frame com-prising upright members and horizontally disposed support members the support members providingsupportforthewalls ofthetent.

5. A tentaccrdingto6laim4vvheFein the support members are connnected slidably to the upright memn- bers.

6. A tent according to any one of the preceding claims wherein the fan in combination with the filter introduces air into the tent the aircontaining from 3000 to 200,000 particles per cubic metre of air and the size of particles is in the range of 0.5 to 25 microns.

7. A tent according to any one of the preceding claims wherein the frame of the tent incorporates frame members at least some of which comprise two or more sections offrame members detachably connected together.

8. Atent according to any one ofthe preceding claims wherein a wall of the tent is common to a compartment having rigid walls.

9. Tents as hereinbefore described with particular reference to the drawings.

10. Tents as hereinbefore claimed in anyone of the preceding claims.