EP2310758A1

EP2310758A1 - Air flow ceiling device

Info

Publication number: EP2310758A1
Application number: EP09766888A
Authority: EP
Inventors: Kjell RØSJØ
Original assignee: AET Arbeidsmiljo og Energiteknikk AS
Current assignee: AET Arbeidsmiljo og Energiteknikk AS
Priority date: 2008-06-16
Filing date: 2009-06-15
Publication date: 2011-04-20
Also published as: US20110151767A1; NO334985B1; WO2009154470A1; NO20082680L; EP2310758A4; CA2728134A1

Abstract

A device for a supply air ceiling of the laminar flow type, a so-called LAF ceiling, which is zoned and where the individual zones are adapted to be supplied with cleaned air with controllable temperature, humidity and volume per time unit. At least one of the clean air zones is adapted to cooperate with or be constituted wholly or partly by a nozzle-equipped unit which is separately supplied with clean air with controllable temperature, humidity and velocity, and where the air velocity out of the nozzle(s) in the unit is higher than the air velocity out of said at least one zone or zones adjacent to the unit. Upstream of the nozzle part of the unit there is arranged a clean air filter and the area of the clean air filter is greater than the cross-section of the said nozzle part.

Description

Air flow ceiling device

The present invention relates to a device for a supply air ceiling of the laminar flow type, a so-called LAF ceiling, which is zoned, and wherein the individual zones are adapted to emit cleaned air with a controllable air volume per time unit, and with controllable temperature and humidity, as disclosed in the preamble of attached claim 1.

Such supply air ceilings, in particular for use in operating theatres, are often referred to as LAF ceilings (Laminar Air Flow Ceilings - LAF ceilings). However, the air exiting such ceilings is not always fully laminar, it being more correct to refer to it as parallel- flowing air.

LAF ceilings for operating theatres are known by several names, as for instance, supply air ceilings, Ultraclean air ceilings, Clean air ceilings, OP-ceilings, UCV for operating theatres, Green Houses, Charnley Boxar, Air Supply Ceilings etc.

In Norway the most commonly used designation is LAF ceiling. What makes the essential difference between supply air ceilings in the ordinary sense and true LAF ceilings is the actual air flow pattern of the supply air. In conventional supply air ceilings, which may be as large as LAF ceilings and may, for many, look confusingly similar, the air is supplied to the area below the ceiling at lower velocities than are required in order to obtain a LAF air flow (laminar flowing air). This means to say that below these supply air ceilings the air is supplied to the occupied zone in a way that causes a turbulent ventilation of the room and in the occupied zone. This type of ventilation is also often referred to as mixing ventilation.

The point at which turbulent air flow will become laminar air flow for large supply air ceilings may be passed if the design of the ceilings is able to produce laminar air flow and the air velocity from the ceilings is uniform across the entire surface and is sufficiently high. This will normally mean that LAF ceilings will have a downward air flow that is of maximum uniformity below that entire surface at a velocity of > 0.3 m/s.

There are devices on the market which combine slightly lower air velocities, down to > 0.25 m/s, with supercooling of the air in relation to the room temperature, so that the weaker velocity gradient will be aided by gravity to prevent the air flow from becoming turbulent before it reaches the occupied zone, that is to say, the patient and instrument table in a hospital operating theatre. However, this increases the risk of cooling the patient with the associated risk of serious complications occurring as a result.

All earlier laminar flow systems have their strong and their weak points. Apart from 5 one solution, as described in WO 95/16168, all types have in common that they do not manage to deal with the conflict that will be present between the doctor's need for a fresh, cool indoor climate in which to work and the patient's need for a warmer climate and not least the even more special needs of the actual surgical incision. Q The said solution according to WO 95/16168 also provides the possibility of reducing the conflicts between the patient's climate needs and the climate needs of the surgeon and others when they are under a LAF flow.

Examples of other prior art include the Dirivent system (primarily developed for use ins industrial halls for guiding ventilation air down into the occupied zone). This system was originally introduced and marketed by Svenska Flaktfabriken, later ABB, and then split into Woods of Colchester (equipment manufacture) and YIT (contractor services). The Dirivent system consists of a plurality of compressed air nozzles which guide compressed air towards a given area and induce downward air flows in other air supplyQ from ventilation on walls. However, this system is not a clean air system.

Furthermore, a system is known where nozzles direct air at a higher velocity than the velocity from the surrounding supply air ceiling which has low- velocity air supply, with the object of directing the air towards a patient area by inducing a larger air flow down₅ from the ceiling. Such a nozzle has a larger diameter (about 3- 5 cm) and greater length (5 -30 cm) than the compressed air injection nozzles in the Dirivent system, but also works at substantially higher velocities than the surrounding air flow apparatus. A major disadvantage with this known system is that air from the room, and which therefore is not sufficiently clean for the patient's needs, is drawn into the downward air0 flow, although the air from the nozzles is clean air.

The Applicant's supply air ceiling of the type AET-V4-UCA for zoned indoor climate in operating theatres involves several means for solving in a more reliable manner the operational disadvantages that other, earlier LAF ceiling types have. This weakness is >₅ due to the lack of a perforated floor under the LAF ceiling in the area into which the laminar air is blown down. Because of the lack of air extraction in the floor immediately below the LAF ceiling (which is in use in other types of clean rooms), the air flow must divide and flow out to all four sides or along a circular or oval outer edge if the ceiling has such an outlet opening. This means that the air begins to divide sooner or later, and a turbulent area is produced where the air flow separates in the central zones. LAF ceilings that were on the market before the Applicant's said supply air ceiling did not have any means for being able to adjust the air flow in this central zone when such problems arose. Earlier, relatively new hospital buildings have run into this problem, which in many cases has led to costly remodelling of a number of clean air ceilings with attendant costs and delays, and in some cases has also necessitated expensive building technical alternations.

Another type of supply air ceiling for operating theatres operates with clean air that is driven through filters and through zones in the ceiling with the aid of different perforation in the outlet opening plates, such as an inner zone in the ceiling that is up to about 4 m2 and an outer zone around the inner zone and which, together with the inner zone, could constitute an area in the range of about 9 -13 m2. Because of the perforation, these zones have different velocities, normally about 0.4 m/s in the central area and 0.2 m/s in the outer area. The purpose of these constructions has been to endeavour to obtain acceptable conditions in a central zone under the LAF ceiling without using an unduly large volume of air per time unit. The idea behind the outer, surrounding zone is that the air that penetrates inwards because the turbulent conditions below this part of the air flow should nevertheless attain a certain elevated cleanliness in a somewhat greater area than the central area of about 2 m x 2 m. Although such ceilings have a skirt hanging from their periphery, the air extraction in the operating theatre at floor level or higher levels will cause the said splitting of the air flow, and the actual patient area will have an unsatisfactory air environment, and even a substantial risk of unclean air owing to the generation of said turbulence. Among other reasons for this is that the air flow out from the supply air ceiling has a limited velocity because the use of micro filters in the under-surface of the ceiling itself reduces the air flow. However, the location of microfϊlters in the whole of the ceiling's underside is advantageous for a number of other reasons.

To further illustrate the prior art from the patent literature reference may be made to US 4781108, DE 2851046, DE 2512679, DE 2260380, WO 95001537, DE 4014795, DE 3633132 and DE 1617977.

Although, therefore, a number of systems have existed for dealing with different climate needs in an operating theatre, they have, however, not been optimal. Because in recent years it has been found to be ever more important to focus on the patient's climate needs, and in particular in the area in which the actual operation takes place, it has gradually become apparent that there is a need to be able to keep the temperature in the operation area (the incision zone) as close to the patient's normal body temperature (37⁰C - 37.5⁰C) as possible, as this will significantly reduce the healing time post-operatively. However, the patient's need for conditioning of the air in an operating theatre, and in particular in the surgical incision area, is as a rule in conflict with the climate needs of the surgeon and the other operation participants. WO 95/16168 describes a solution which comprises one or more zones that have means for adjusting the climate, including humidification. However, the need for air velocity increases with rising temperature and humidity when a known solution of this type is used.

It is therefore an object of the present invention to meet the need that exists, but which hitherto has not been met with a satisfactory solution. Accordingly, it is an object of the invention to ensure best possible climatic conditions for the patient, with means for doing so in particular at the surgical incision throughout the operation.

It is an object of the invention to increase the supply of air in the central area and thus lower the level of the area in which the air centrally begins to divide and pass into a turbulently ventilated area.

In addition to the many advantages the Applicant's known supply air ceiling (AET-V4- UCA) has in order to obtain a controlled directed air flow which reaches operating and instrument table levels, it is an object of the invention to provide to a substantial extent an efficient way of supporting the guiding of laminar or parallel air flow right down to the intended areas.

The invention meets a combined need by more easily and with better control directing the LAF flow down to the patient area, and supplying a smaller area of the patient area, i.e., the area of the surgical incision, with even warmer and more highly humidified air, as high as the moisture saturation level of the air, if so desired.

According to the invention, this is solved primarily in that at least one of the clean air zones is adapted to cooperate with or is constituted wholly or partly by a nozzle- equipped unit which is separately supplied with clean air with controllable temperature, humidity and velocity, and where the air velocity from the nozzle(s) in the unit is higher than the air velocity from said at least one zone or zones adjacent to the unit. Moreover, a clean air filter is mounted upstream of the unit's nozzle part, the area of the clean air filter being greater than the cross-section of said nozzle part.

Additional embodiments of the device will be apparent from the attached subsidiary claims, and from the invention described below with reference to the attached drawings, which illustrate embodiments that are non-limiting for the invention.

Fig. 1 is a schematic section of a zoned supply air ceiling with a device according to the ^■ invention.

Fig. 2 is a vertical section through a first embodiment of the device.

Fig. 3 is a schematic vertical section through a second embodiment of the device.

Fig. 4 is a schematic view of a device as shown in Figs. 2 and 3 seen from below.

Fig. 5 is a schematic view of a zoned supply air ceiling with a third embodiment of the device.

Fig. 6 is a perspective sectional view of the third embodiment of the invention.

Fig. 7 is a perspective bottom view of a fourth embodiment of the device cooperating with a zone area of a supply air ceiling.

Fig. 8 is a perspective bottom view of a fifth embodiment of the device cooperating with a zone area of a supply air ceiling.

Fig. 9 shows the section IX-IX in Fig. 8.

Fig. 10 illustrates an assembled nozzle system for installation under a supply air ceiling in cooperation with clean air zone(s) therein.

Fig. 11 illustrates an example of a possible variation for a plurality of nozzles with common air manifold. Fig. 12 illustrates a zoned patient zone which has special support zones and a separate surgical incision zone for a typical operating theatre with a sixth embodiment of the device.

5 Fig. 13 shows the section XIII-XIII in Fig. 12.

Fig. 14 shows a seventh embodiment of the device for cooperation with a clean air zone in a supply air ceiling. o In the description terms such as "ultraclean air" and "clean air" are used. In the context of an operating theatre, these terms should be regarded as identical, in any event where the patient zone and/or incision zone are concerned.

The device according to the invention is particularly suitable as additional equipments for installation in supply air ceilings in the central zone thereof, which is as a rule related to the patient zone. As mentioned above, such supply air ceilings are also often referred to as LAF ceilings, parallel flow air unit, operation ceilings (Op-ceilings), clean air ceilings or Ultra Clean ventilation ceilings in general and in particular when these types are used in operating theatres and associated rooms in hospitals. The device will0 be especially suitable for use together with or installed in a supply air ceiling as supplied by the Applicant, for example, an ultraclean air ceiling as described wholly or partly in said WO 95/16168.

The device may consists of one nozzle-equipped unit or several nozzle-equipped units,S which are placed centrally in clean air ceilings in general or in particular in the patient zone or central zone in, for example, a clean air ceiling designated AET-V4-UCA supplied by the Applicant, in order to directionally direct an air and/or steam stream towards a specific area within the patient area or another work object positioned under the LAF ceiling. The device according to the invention will also help to strengthen the0 air flow in this important critical area by countering premature breakup of parallel air flow from the supply air ceiling.

The device can advantageously also be used with existing clean air ceilings of different designs or future versions of such clean air ceilings. 5

As will be described in more detail, the device according to the invention will be capable of specially conditioning and directing a central, limited air flow down into a specific extra zone or separate zone nearest the patient and/or surgical incision and at the same time strengthen the air flow towards this zone from the clean air ceiling in which it is installed. The device can be used in many known constructions that are in use in, for example, operating theatres, industrial halls or other places, or new types of supply air ceilings based on the same or new principles. The object is in any case to give support to and direct the normally warmer and/or extra humidified air down into lower lying areas in a room. The use of the device according to the invention will primarily be well suited for the patient and/or surgical incision zone under a clean air ceiling as the air induction produced directs the surrounding air from the clean air ceiling down to intended areas in a more reliable manner and prevents the premature breakup of the laminar or parallel air flow. Thus, both the clean air and the specially conditioned air are directed more reliably into the central patient area and in particular the operation area, which is the most important of all.

The device according to the invention, which is included in or cooperates with the supply air ceiling, will be able to reduce the need to increase the air flow via the zone's or zones' fans just as much, but will, with a more reliable, sound-improved and energy- improved solution, support the air flow that is directed down towards the patient and also the surgical incision when this is a separate part of the patient zone (zone in zone).

The present device also allows the use of high-grade humidified ultraclean air from the nozzles. For this purpose, steam or water fog can be used that is produced by different methods, for example by using steam atomizers or ultatrasonic water atomisers. High pressure fog atomisers may, for example, be mounted directly in air supply pipes for increased induction effect.

Although it is possible to use nozzles which draw along other clean air from the zone in which the nozzle is located, it is also possible to use an ejector principle where active suction of the clean air which otherwise exits a clean air zone is produced such that this air is efficiently mixed with the rest of the air exiting the nozzle. When such a solution is used in a nozzle-equipped unit, it may be expedient to be able to manoeuvre the unit manually or automatically steplessly in two dimensions in a horizontal plane. The ejector principle can be used either in that ultraclean nozzle air is forced through a central duct in the nozzle structure and that there are inclined inlets in this duct for clean air with lower velocity which comes from cooperating clean air zone(s) in the supply air ceiling, or that ultraclean air from cooperating clean air zone(s) is forced through a central duct of the nozzle structure and that there are inclined inlets in this duct for clean air with higher flow rate which comes from a separate clean air supply that is specifically intended for a nozzle unit and which normally will not be available in a supply air ceiling of known type.

It is also conceivable that the ejector solution may wholly or partly be replaced by or supplemented with the aforementioned known standard devices in a surrounding support system for additional strengthening of the downflow of the air. In this case, the last-mentioned means may also be placed in zones surrounding the patient and/or the incision zone, one or a series.

Installation conditions in, for example, operating theatres may require that LAF ceilings are mounted higher in the room with the air supply at a level that will mean that it is more uncertain that the LAF air flow will reach the intended area.

A nozzle such as that intended to be used, either one or more in a unit, or which cooperates in some other way, may expediently consist of an adjustable or stationary pipe or several pipes in combination which can be directed towards the surgical incision and which are supplied with ultra clean, warmed and humidified air. Such an air device can be adjusted manually or via an electric direction control.

The conditioning of the air (temperature, humidity and/or velocity) takes place automatically after adjustment by manipulating settings on a known per se control panel, which in this case has been expanded to include a control function also for one or more nozzle units. Such control panels for zone control of supply air ceilings of, for example said type AET-V4-UCA are, as mentioned, well known.

It will be understood, especially for use in operating theatres, that the device must be made of such material or materials that it is possible to be able to carry out an efficient, sterilisation cleaning, for example, by autoclaving. Although this is an essential requirement, it is nevertheless possible that some parts of the device, for example, the nozzles, may be made of a disposable material that is disposed of after being used for a certain time. In some cases it may also be desirable that the nozzles are replaceable in order, in an installation with at least one nozzle unit, to be able to alter the properties of the unit.

The attached drawing figures will now be briefly described. Fig. 1 shows an example of a supply air ceiling 1 divided into air flow zones 2 -10. The zones will be capable of having individual conditioning with regard to the temperature, humidity and velocity of the clean air, but it is also conceivable that some of the zones have a common conditioning plant. Another arrangement of the zones is of course also possible, as for example described in said WO 95/16168, or as marketed by the

Applicant in connection with the supply air ceiling AET-V4-UCA. hi addition, a nozzle unit 11 is indicated in the example where the clean air which comes out has a higher velocity than that exiting zones 2 - 10. Although only one nozzle unit 11 is shown in the figure, it will be understood that it is possible to use two or more nozzle units, either in cooperation with at least one of the zones 2 - 10 or mounted inside one or more of these.

In Fig. 2 there is shown a detachable adapter 12 which can be a plate box of stainless steel or other autoclavable material. Clamps, fastening hooks, rapid fasteners or mounting locks 13 ensure that the adapter 12 is held in position during use. When the nozzles are designed for induction, i.e., that they can effect intake of clean air from cooperating ceiling zone(s), they consist of an outer sleeve 14 with fastening 14' to an inner pipe 15. The device as shown in Fig. 2 has an inlet duct 16, a first pressure chamber 17 and a second air chamber 18. An air filter 19, for example, of the HEPA type or more efficient air filter is replaceably installed in a frame 20 inside the duct 16. The duct is expediently provided externally with insulating material 16'. This material will be of a combined sound-proofing and thermal type, so that it can also contribute to the internal damping of sound inside the LAF ceiling, which may be advantageous. The reference numeral 21 indicates a profile frame for a LAF ceiling filter, i.e., a frame which traditionally will be present in LAF ceilings, but which in connection with the invention supports the device by supporting the duct 16. Sealing 22 is found between the inlet and the other pressure chambers of the LAF ceiling, i.e., such that as regards pressure and air, the device is separated inside the supply air ceiling from the air environment in the zones. On top of the duct 16 there are suitable duct connections 23 for connection to air conditioning equipment such as air heaters, air coolers, air humidifiers and fans (not shown). To remove the condensation water in the adapter, there is advantageously provided an extractor 24 whose lower end 24' opens into the adapter. The extractor line 24, in connection with the detachability of the adapter 12, may have a releasable coupling 24". The pipes extend some distance 15' into the adapter, which means that condensation water can lie some way along said distance before it is drawn out via the extractor 24. The under-surface of the LAF ceiling lattice is indicated by the reference numeral 25. It should be noted in connection with Fig. 2 that the cross-section A of an upper part of the duct is substantially larger than the area B downstream in the duct. This is of major importance for the air velocity in the chamber 18. Because the filter 19 for a defined area has limited air throughflow volume per time unit, it is important that the filter has as large an area as possible, hi the chosen example the area ratio A:B can, for example, be 3:l.

The solution that is shown in Fig. 3 may, when the nozzles are designed for induction, i.e., that they can effect intake of clean air from cooperating ceiling zone(s), consist of an outer sleeve 26 with fastening 26' to an inner pipe 26". The pipes 26" are releasably fastened to an adapter 27 with bayonet fasteners, screw fasteners or snap fasteners 27'. Hoses 28 which are provided with insulation 28' are passed to a (non- illustrated) conditioning plant to give air that is to exit the nozzles the desired cleanliness, temperature, humidity and velocity. The reference numeral 27" denotes the top of the supply air ceiling but could optionally form said profile frame 21.

As mentioned above, supply air ceilings, especially for operating theatres, may preferably be zoned, the individual zones being adapted to emit cleaned air with controllable temperature, humidity and velocity. In the solutions shown in Figs. 1-3, at least one of the zones consists of a nozzle equipped unit which is separately supplied with clean air with controllable temperature, humidity and velocity, and where the air velocity out of the nozzles in the unit is higher than the air velocity of said at least one zone or zones adjacent to the unit. The unit is replaceably installed in the supply air ceiling.

In the solution shown in Figs. 5 and 6, the concept is that there is a supply air ceiling 29 with a plurality of clean air zones 30 -54, where these zones may, for example, have a cooperating arrangement as shown and described in the Applicant's WO 95/16168, or as marketed by the Applicant in connection with the supply air ceiling AET-V4-UCA. At least one of the clean air zones, here for example, zone 42, is adapted to cooperate with a nozzle-equipped unit 55 which is separately supplied with clean air with controllable temperature, humidity and velocity, and where the air velocity out of the nozzle(s) in the unit is higher than the air velocity out of the said at least one zone or zones adjacent to the unit. As shown in Fig. 6. the zone is in a standard way provided with a clean air filter 56 which rests on a frame 57, 57'. The nozzle unit 55 is supplied with clean air via a pipe 58 which is passed into a funnel 59, i.e., a sleeve with distended portion facing the underside of the supply air ceiling for intake of clean air from said at least one clean air zone 42 effected by air throughflow through the nozzle of the separately supplied clean air through pipe 58 and for mixing the air flows at the downstream end of the nozzle, i.e., that it creates a vacuum which acts on the air exiting the zone 42. The unit 55 is advantageously movable and positionable below a chosen one of the clean air zones. The unit may, for example, on positioning at a chosen air zone be fastenable to the underside of the supply air ceiling by means of magnetic devices 60. The unit 55 is supported by at least one telescopic arm which is pivotally fastened to the supply air ceiling and is movable approximately parallel to the underside of the supply air ceiling. In one possible embodiment, the pipe 58 maybe of a telescopic, extendible type and at the same time have such rigidity that it can support the unit 55. If such a unit is to have a plurality of nozzles, which means it will be relatively heavy, it may be useful to use, for example, at least two telescopic supporting arms, or that the unit rests on a trolley that is movable in two dimensions either by manual actuation or by means of electrically controllable movement. The pipe 58 may optionally receive its air supply of conditioned air via a supporting column 61 in the supply air ceiling.

Fig. 7 shows a solution designed for cooperation with a selected zone 62, where nozzles 63-68 receive a common supply of clean air via common supply pipe 69 from a conditioning plant (not shown). Air exiting the zone 62, will, at a lower velocity than the air though each one of the pipes or sleeves 63'; 64'; 65'; 66'; 67'; 68', enter a space between a pipe 63'; 64'; 65'; 66'; 67'; 68' and a sleeve 63"; 64"; 65"; 66"; 67"; 68" and will, because of an ejector effect, be forced out together with the air supplied via the pipe 69. The reference number 62' indicates a traditional filter of the HEPA type or even better filter.

Figs. 8 and 9 show another embodiment of the device. In this case, sets of nozzles 70, 70'; 71, 71'; 72, 72' have been supplied with conditioned clean air via respective supply pipes 70"; 71"; 72".

The nozzles discharge air at a higher velocity than- the air velocity out of cooperating zone 73 in the supply air ceiling. The main point here is that the nozzles cooperate with a zone which initially, for example, is directed towards a patient or a surgical incision. The pipes 70" ; 71 " ; 72" are passed through the supply air ceiling 74 via a panel 75 thereof and may, for example, be pivotal in relation to the panel, as indicated for the pipe 72" in Fig. 8. In addition, the pipes 70"; 71"; 72" may telescopically adjustable in length as indicated in Fig. 9.

As an alternative to the solution in Figs. 8 and 9, it is envisaged, as shown in Fig. 10, that the pipes 73; 74; 75 are fastened to a common air supply pipe 76 that is stationary, so that the pipes are not pivotal or extendible, i.e., that associated respective nozzles, commonly designated by respectively 73; 74' and 75' are installed so as to be stationary below selected zone or zones.

Regardless of whether two or more nozzles are chosen, these nozzles 77 — 80 can expediently have cross-section D2; D3; D4, D5 and likewise adapted inter-spacing Bl; B2; B3. In addition, the respective length of the nozzles Ll; L2; L3; L4 may similarly be expediently adapted, as visualised in Fig. 11. The supply pipe 81 may have a suitable diameter Dl . The lengths of the nozzles may be the same or slightly different. Diameter will vary dependent on heights at which the respective LAF ceilings are mounted.

The embodiment shown in Figs. 12 and 13 is a visualisation of the actual patient zone in a supply air ceiling 82 of the type corresponding to the solution in said WO 95/16168 with additional division into clean air zones 83-86, and a central zone or surgical incision zone 87 which is provided with a nozzle 88 that may have an outlet cross-section C that is adapted to the size of the LAF ceiling and its height above floor level. As for the supply air ceilings discussed above, the zones are conditioned individually or in groups. The nozzle 88 has a flange 89 for coupling to a duct 90 which has insulation 90'. The duct 90 leads to a conditioning plant which supplies clean air with a desired temperature, humidity and velocity. The air velocity out of the nozzle 88 will be greater, and often substantially greater, than the air velocity out of the adjacent zones 83-86.

Fig. 14 shows a variant of the nozzles that are shown in the earlier drawing figures. In this case, the nozzle unit 91 is specifically intended for mounting to an air supply zone 92 in a supply air ceiling. Here it is intended to use a plurality of nozzles 93-95, in the chosen example three. Each nozzle has a pipe 93',; 94'; 95' for initially passing clean air from the zone 92 at a first velocity, and an air injection pipe 93"; 94"; 95" for passing conditioned clean air which has a second velocity greater than the first velocity, so that the mixed air exiting the nozzle 93; 94; 95 has a velocity that is almost equal to the second velocity. The clean air that is injected in this way exits the conditioning plant (not shown) with desired temperature, humidity and velocity via a hose 97, releasable coupling 96' and a supply pipe 96 which runs to each of the air injection pipes.

Conditioning means for providing the specially conditioned air for the surgical incision area will be additional zone equipment with essentially the same structure as the units for the other zone or zones. The conditioning means can be placed in the supply air ceiling if there is room when the nozzle unit or units are optionally to be retrofitted or mounted externally. In connection with the new construction of the supply air ceiling, if there is sufficient ceiling height, space can be given to such a plant (conditioning means) for the device. But for a number of reasons it will be advantageous to place these special conditioning means, including means for high-grade humidification of the surgical incision area, in a separate technical room as also is and will be done in connection with the zone conditioning means according to the solution described in WO 95/16168.

The pipes that are used for supply pipes and nozzle pipes may be round or may have other geometric shapes. Preferably, they can be made of stainless steel or other suitable hygienic and autoclavable material. The pipes may be connected to the conditioning unit or units singly or via, for example, a common pressure chamber. This in turn may be zoned itself. The chamber will be connected to the conditioning source. A plurality of individual conditioning sources is possible if it should be found advantageous to have zoning of climate and velocities. Parameters which control this may be how the individual nozzles in a nozzle system are arranged in an expedient pattern, so that optimal indication of surrounding air is obtained for increasing the velocity and between directing of ultraclean air towards the, as a rule, central patient zone. This will give important support to the whole LAF flow from the supply air ceiling (which supplies ultraclean air) and not least for the whole of the patient zone or the area.

The pressure chamber, pipe connections, nozzles and sleeves are advantageously made so as to have rapid connectors with bayonet fasteners and the like; i.e. rapid and secure mounting devices of known types for rapid mounting and dismantling in connection with sterilising and autoclaving.

Claims

P a t e n t c l a i m s

1.

A device for a supply air ceiling of the laminar flow type, a so-called LAF ceiling, which is zoned and where the individual zones are adapted to be supplied with cleaned air with controllable air volume per time unit, and with controllable temperature and humidity, characterised in that at least one of the clean air zones is adapted to cooperate with or be constituted wholly or partly by a nozzle-equipped unit which is separately supplied with clean air with controllable temperature, humidity and velocity, and where the air velocity out of the nozzle(s) in the unit is higher than the air velocity out of said at least one zone or zones adjacent to the unit; that upstream of the nozzle part of the unit there is arranged a clean air filter; and that the area of the clean air filter is greater than the cross-section of the said nozzle part.

2.

A device as disclosed in claim 1, characterised in that the unit is replaceably mounted in the supply air ceiling.

3.

A device as disclosed in claim 1, characterised in that the unit is movable and positionable below a selected one of the clean air zones.

4.

A device as disclosed in claim 3, characterised in that the unit during the positioning at a selected clean air zone is fastenable to the underside of the supply air ceiling by means of magnetic devices.

5.

A device as disclosed in claim 3, characterised in that the unit is supported by at least one telescopic arm that is pivotally attached to the supply air ceiling and is movable approximately parallel to the underside of the supply air ceiling.

6.

A device as disclosed in any one of claims 1-5, characterised in that the nozzle or nozzles are surrounded by a sleeve with a distended portion facing the underside of the supply air ceiling for intake of clean air from said at least one clean air zone effected by air throughflow through the nozzle of the separately supplied clean air and for mixing of the air flows at the downstream end of the nozzle.

7. A device as disclosed in any one of claims 1 — 5, for cooperation with a clean air zone in a supply air ceiling, characterised in that the nozzle or nozzles consist of a pipe adapted to receive clean air at a first velocity from said clean air zone, and an air injection pipe which is passed in through the side of the pipe, adapted to supply conditioned clean air at a second velocity that is greater than the first velocity, so that the separately supplied clean air flows are mixed within the nozzle and passed out thence at a velocity approximately equal to the second velocity.

A device as disclosed in any one of claims 1-7, characterised in that the nozzle or nozzles in the unit are connected via hoses to a supply of clean air.