GB2127954A - Air supply ceiling - Google Patents

Abstract

An air supply ceiling, e.g. for an operating theatre, may seriously interfere with the positioning of lighting or other ceiling mounted equipment since it is not possible to pass a suspension element through the air supply ceiling without serious risk of allowing non-sterile air to by-pass the sterile filter forming part of the ceiling. According to the present invention an air supply ceiling includes an air duct (15) having an air inlet with a sterilising filter (19) through which air is blown is indicated by arrow (21). This duct (15) is mounted in an aperture in a false ceiling (12) and the lower wall of the duct 15 is provided with a series of areas of or other ceiling mounted equipment perforated plates and flow compensators in the form of a foam mat. Thus, where suspension elements (61, 71) pass through the lower wall, there is no risk of leakage of non-sterile air since the air is already sterilized. Holes for the passage of suspension units (61,71) through the upper wall of the duct (15) are easily sealed. <IMAGE>

Description

SPECIFICATION Air supply ceiling The invention relates to an air supply ceiling for a sterile room, comprising a fan or blower, a mechanical filter and an airsupply duct having an air discharge opening which leads into the room and is provided with a plurality of areas of perforated plates and a flow compensator.

The theoretical bases of contamination in the operating theatre are discussed in Swiss Med 2, No. 5, pages 89-94, in which particular importance is given to air conditioning by means ofthe conditioning apparatuswhich are used. The clean air supplied to the room issues from an air supply ceiling, which is built into the ceiling of the operating theatre, in the form of a downwards, almost laminar piston flow, and circular flows, the so-cal led secondary eddies, form in front of the side walls ofthe operating theatre. The contamination and heat-loaded air is extracted from the operating theatre from slits near the floor and below the ceiling.

Taking as a basis proposals of Prof. J. Chamley, air air supply ceiling has been developed which is intended to guarantee a particularly sterile clean room zone where the surgical operation is being carried out. In order to obtain, as far as possible, the required laminar piston flow, a plurality of areas of perforated plates are provided at the air exhaust opening of the air supply duct ofthe airsupply ceiling, on which perforated plates a mechanical filter block is disposed. This mechanical filter simultaneously acts as a flow compensator which assists the formation of the piston flow in the operating theatre.

However, this type of air supply ceiling has the disadvantage that passages, such as are necessary for mounting lighting units on the ceiling ofthe building, are only possible with considerable technical difficulty, since it is necessary to ensure that unfiltered supply airatthe passage does notentertheroom in an uncontrolled manner. This requirement results in considerable sealing problems in the case of passages which therefore, in the above-mentioned air supply ceiling, are only accessible at specially arranged locations. Howeverthe mounting point of ceiling lights, for example, is determined by the necessary illumination ofthe operating area, which does not correspond with the mounting possibilities ofthe air supply ceiling.

An object ofthe invention is therefore to provide an air supply ceiling which, while maintaining the laminar piston flow ofthe air supply, does not entail any restrictions as regards the positioning of passages.

Forthis purpose, according to the invention, an air supply ceiling for a sterile room is provided which comprises a fan or blower, a mechanical filter, an air supply duct having an air discharge opening which leads into the room and is provided with a plurality of areas of perforated plates and a flow compensator, the mechanical filter being secured in front of the air inlet opening and foam matwith open pores being placed on the perforated plate.

Any required passage can bemadethroughthe perforated plate and the foam mat at any desired point without special sealing, as the air leaving the air supply duct is alreadyfiltered and any supply air which leaves at the passage, while by-passing the foam mat, does not noticeably affect the piston flow. A passagethrough the upper wall ofthe air supply duct may be easilyformed and sealed at any desired location.

The foam mat, which is resistantto all light-duty detergents and practically all conventional disinfectants, may advantageously have a pore size of 30 pores per inch. It has also proved advantageous for approximately 40% ofthe perforated plate area to be occupied by the free cross-sectional areas of all the holes of the perforated plate.

The invention is described in detail in the following with reference to an embodiment illustrated in the accompanying drawing, in which: Figure lisa schematic illustration of an air supply ceiling, built into an operating theatre, with emerging air flows; Figure 2 is a schematic detailed illustration of the air supply ceiling offigure 1; Figure 3 is a viewfrom below of a perforated plate of the air supply ceiling according to figure l,the punched holes only being indicated in one section; Figure 4 is a section through a perforated plate along the line lV-lV offigure 3; Figure 5 illustrates a further embodiment of the invention; and Figure 6 is a detail of a third embodiment of the invention.

The operating table 5 with a side table, above which a ceiling light 6 is suspended from the ceiling, is disposed approximately in the centre ofthe schematically illustrated operating theatre 1. Another additional light7 is secured to the ceiling 4. An exhaust air opening 8 is disposed in a sidewall 2just above the floor 3 and a further exhaust air opening 9 is disposed below the air supply ceiling, which is designated as a whole by 10.

The air supply ceiling loins secured to the side walls 2 and/or, in a mannerwhich is not shown, to the ceiling 4 and draws supply airfrom an opening 11 in the side wall 2 above a suspended ceiling section 12 extending round the side walls. The central section ofthe air supply ceiling 10is provided with an elongated air supply duct 15, which opens downwards into the room, where it is provided with devices which will be described below. An air inlet opening 17 which, in this embodiment of the invention, is formed laterally at the air supply duct 15, is closed by a mechanical filter 19, to which supply air is fed from an opening 11 buy a fan or blower, which is not shown, in the direction ofthe arrow 21.

Passages 23, 25 are provided through the air supply ceiling 10 in order to allow passageforthe suspension devices 61 and 71, which are only schematically illustrated, forthe ceiling light 6 and the additional light7 respectively.

According to figure 2 the air supply duct 15 is a square section generally square housing downwardly directed air exhaust opening 27 of which is of a size which corresponds to the required piston flow. Avery wide-meshed screen profile ofT-beams, of which a longitudinal beam 29 and the tranverse beams 31,33 are illustrated in figure 2, extends over the opening 27 and is connected to the suspended ceiling section 12 extending round the edge ofthe air supply duct 15.

The mesh size ofthis screen profile can be 60 x 60 cm which can be determined according to manufacturing considerations and also selected as desired in a different manner. The screen profile defines squae (or rectangular) areas, one of which is designated by 35.

As the other areas are similarly formed, only the area 35 which be described further.

In the area 35 a perforated plate 40 (see also figures 3 and 4) is suspended by means of locking hooks, which are schematically illustrated at42 and can be fastened to the beams of the screen profile. Each perforated plate 40 has upwardly bent edges 44,46, thus forming a trough into which a foam mat 50, whieh covers the entire base ofthe trough, is placed. The fitted, one-piece foam mat 50 covers all the holes (except those forthe locking hooks 42) which are punched out ofthe base 47 of the perforated platt 4t1 The hole pattern, which is advantageously formed in u symmetrical manner, is shown in detail at 48. The overall area ofthe openings of all the holes of the pattern 48 is approximately 40% of the total area of the base 47 of the perforated plate.The latter may consi of V2A steel (material 4301) having thickness of 1 mm.

The foam mat is advantageously a Scott filter foam with open pores, which can be obtained from the Scott-Paper-Company, Philadelphia, U.S.A. The pore size ofthefoam mat is 30 pores per inch. The material has a softening point of 190"C and a decomposition point of 270"C and is resistantto all light-duty detergents and to practically all conventional disinfectants. When the thickness of the foam mat is 15 mm and the air supply speed is between 0.25 and 0.3 m/s, the pressure loss over the described air supply ceilina is between 4 and 6 Pa. The described air supply ceiling has the considerable advantage that the air supply flowing through the air supply duct 15 is already sterilized clean air.The passages 23 and 25 can therefore be formed at any desired point in the lower wall ofthe air supply duct without any special sealing measures by cutting portions out of the perforated plate 40 and the foam mat 50. Any clean air flowing through the passages past the foam mat does not influence either the sterile condition of the air supply introduced into the room 1 orthe desired laminar piston flow. Apertures for suspending means 61,71 also need to be formed in the upper wall ofthe air supply duct 15, butthese are simply formed by cutting where desired and sealing around the suspending means 61,71 is achieved by suitable flexible seals or diaphragms.

According to figure 5, some of the air in the room 1 can be taken from one of the lateral secondary eddies, for example the secondary eddy 52 according to the arrow 54, and supplied via a cooling device 56to the inlet side of a fan or blower 58 after being mixed with the air introduced from outside according to the arrow 55. The discharge side of the fan or blower 58 is coupled to the mechanical filter 19 byway of an air duct 57 and a sound absorber 59, which is fitted in the latter. The exhaust air openings 51 and 53, which correspond to the openings 8 and 9 are provided on the opposite wall of the room 1.

Figure6showsthatthe mechanical filter 19a may also be secured to the upper side 65 of the air supply duct 15a byway of air inlet opening 17a, which is provided atthis point. The air supply duct 1 5a can also be lowered by part of its height with respect to the surrounding ceiling section 12 into the room 1.

The invention is not restricted to the details of the embodiments described above. On the contrary, the combination ofthe perforated plate 40 and the foam mat 50 can advantageously be used in other air conditioning apparatus. The factthatthis combination can be easily serviced and cleaned is particularly advantageous.

Claims (4)

1. Air supply ceiling for a sterile room, comprising i fan or blower, a mechanical filter and an air supply duct having an air discharge opening which leads into the room and is provided with a plurality of areas of parforated plates and a flow compensator, in which the rnechanical filter is secured in front ofthe air inlet opening ofthe air supply duct and a foam matwith oper pores is placed on each perforated plate.

2. Air supply ceiling as claimed in claim 1, in which the foam mat, which is resistant to light-duty detergents and disinfectants, has a pore size of 30 pores per inch.

3. Air supply ceiling as claimed in claim 1 or2, in which the free cross-sectional area of the punched holes of the perforated plate is approximately 40% of the basal surface ofthe perforated plate.

4. Air supply ceiling substantially as hereinbefore described with reference to the accompanying drawings.