AIR FLOW IN A CLEAN ROOM

TECHNICAL FIELD The present invention relates to protective air flow systems in clean rooms. In particular, the present in vention relates to control of a fluid flow pattern within a clean room. BACKGROUND

HVAC, i.e. heating, ventilating, and air con ditioning, is a technology for indoor environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a sub-discipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. Refrigeration is sometimes added to the abbreviation as HVAC&R or HVACR, or ventilating is dropped out as in HACR (such as in the designation of HACR-rated circuit breakers). HVAC is important in in door design where safe and healthy building conditions are regulated with respect to temperature and humidi ty, using fresh air from outdoors. Ventilating (the V in HVAC) is the process of changing or replacing air in any space to provide high indoor air quality, for example to control tempera ture, replenish oxygen, or remove moisture, odors, smoke, heat, dust, airborne bacteria, and carbon diox- ide. Ventilation is used to remove unpleasant smells and excessive moisture, introduce outside air, to keep interior building air circulating, and to prevent stagnation of the interior air. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. Methods for ventilat ing a building may be divided into mechanical or forced and natural types.

The current applications of air distribution principles for critical environments, such as clean rooms like patient and isolation rooms or other rooms, where patients are treated, are based on a simplified thinking of a zoning principle to be used in most critical (EN standard cleanrooms) environments and a dilution principle to be used in other rooms. In many cases, this thinking has led in practice to an unsat isfactory realization of the airflow pattern within the critical environments. In particular in operating rooms where invasive methods are used to treat pa tients, the presence of operational personnel as a contaminant source in the proximity of the patient causes special challenges in the prevention of wound contamination. Also, the nursing staff in proximity of the patients are heavily exposed to the air exhaled by the patients. The exhaled air contains microbes, that may cause infections to nurses, as well as remains of the medication which may cause various symptoms or discomfort by smells etc. in a long term.

On the other hand, mixing solutions that are currently used in operating rooms are not based on a throughout thinking, and they can fail to provide tru ly mixed conditions and certainly lack the prevention of the reverse flow into the most critical areas as well as the ability to control the thermal environ ment and velocity conditions for occupation. One of the common methods is based on the usage of swirl dif fusers in the ceiling, typically located symmetrically within the room. This system has both a risk of allow ing contaminated air to enter the wound area from the floor level and no means to control the velocity con- ditions. A second very common method used in the past is a high wall or ceiling/wall corner supply, which is very sensible to the temperature difference between the supply and the room air. Depending on the opera tional conditions, it may blow the air past the oper ating personnel prior to entering the wound area or blow the air directly to the floor, thus bringing all the settled contaminants into the operational area. A third very common system is a parallel flow system, in which the air is supplied into the operating area from two elongated air supply devices that are parallel to the operating theater. Compared to the previously men tioned systems, this system has the advantage of providing air supply to the center of the critical zone. However, the design of such a system is based on the avoidance of excessive velocity within the center without the possibility to adjust the jet or velocity. The design is based only on the distance of the air supply device from the center. Thus, the air supply jet or the jet velocity is not adjustable. The reverse flow from the periphery poses a risk in many clean rooms.

Common to all currently used mixing type systems is that they are not capable of providing a flexible air supply flows for different scenarios in a clean room.

SUMMARY

The objective of the device/method is to provide a protective air supply system and a method for supply ing a protective air flow in a clean room. The object is achieved by the features of the independent claims.

According to a first aspect, the present invention provides a protective air supply system for control ling air supply flows in a clean room, wherein the clean room comprises a clean area subject to contami nation. The system comprises a first air supply dif fuser and a second air supply diffuser, arranged with in a ceiling of the clean room and on opposite sides of the clean area and spaced from side walls of the clean room. Each of the supply air diffusers is con figured to diffuse a first air flow, having a first air flow volume A 1/s, directed along a ceiling of the clean room and towards the clean area; and a second air flow, having a second air flow volume B 1/s, di rected along the ceiling of the clean room and towards a perimeter of the clean room. Further, the system comprises a controller coupled to the air supply dif fusers, and the controller is configured to adjust the first air flow volume A and the second air flow volume B and their ratio.

The advantage of the system is that the ventilation and the supply air flows may be adjusted in different scenarios having different needs, and to meet the re quirements of thermal comfort and the safety of the people in the clean room.

In an embodiment of the system, the combined air flow volume A+B is adjustable from 70 1/s to 2001/s.

In an embodiment of the system, the controller is con figured to adjust the ratio of the first air flow vol ume A and the second air flow volume B between 100:0 and 0:100.

In an embodiment of the system, the controller is con figured to switch between an isolation mode and a nor mal patient mode. In an embodiment of the system, in the normal patient mode the second air flow volume B is 0 1/s and the first air flow volume A is more than 01/s.

In an embodiment of the system, in the isolation mode the first air flow volume A and the second air flow volume B ratio is 1:1.

In an embodiment of the system, in the isolation mode the first air flow volume A is the same as in normal patient mode and the second air flow volume B is in creased.

In an embodiment of the system, in the normal patient mode the combined air flow volume is 701/s.

In an embodiment of the system, in the isolation mode the combined air flow volume is 200 1/s.

In an embodiment of the system, each of the supply air diffusers is provided with multiple nozzles.

In an embodiment of the system, at least some of the nozzles are closable.

In an embodiment of the system, the supply air diffus ers comprise separate chambers for the air to be dif fused as the first air flow and the second air flow.

According to another aspect, a method is provided for providing protective air flow in a clean room, wherein the clean room comprises a clean area subject to con tamination, comprising steps of:

- having a normal patient mode, wherein

- diffusing a first air flows from a first supply air diffuser and a second supply air diffuser, arranged within a ceiling of the clean room and on opposite sides of the clean area, each first air flow being di rected along the ceiling and towards the clean area and towards each other, so that the first air flow and the second air flow are arranged to collide inside the clean area so that the combined air flow is directed towards the floor of the clean area and the clean area is flushed with the combined air flow,

- initiating an isolation mode, wherein, additionally to the normal patient mode,

- diffusing a second air flows from the first supply air diffuser and the second supply air diffuser, each second air flow being directed towards the perimeter of the clean room and in opposite direction than the first air flow from the same supply air diffuser.

In an embodiment of the method, supplying air volume A+B of 701/s in the normal patient mode.

In an embodiment of the method, increasing the supply air volume A+B to 200 1/s when the isolation mode is initiated.

In an embodiment of the method, adjusting the ratio of the first air flow volume A and the second air flow volume B between 100:0 and 0:100

It is to be understood that the aspects and embodi ments of the invention described above may be used in any combination with each other. Several of the as pects and embodiments may be combined together to form a further embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to pro vide a further understanding of the invention and con stitute a part of this specification, illustrate em bodiments of the invention and together with the de- scription help to explain the principles of the inven tion. In the drawings:

Fig. 1 shows a cross section of a clean room from side when system is in a normal patient mode,

Fig. 2 shows a cross section of a clean room from above when the system is in a normal patient mode,

Fig. 3 shows a cross section of a clean room from side when system is in an isolation mode,

Fig. 4 shows a cross section of a clean room from above when the system is in the isolation mode,

Fig. 5 shows a first air supply diffuser and a second air supply diffuser according to an embodiment,

Fig. 6 shows air supply diffusers arranged in circum ferential form, i.e. ring-type air supply diffuser ac cording to an embodiment, and

Fig. 7 shows a cover panel of an air supply diffuser comprising multiple nozzles.

DETAILED DESCRIPTION

The clean room described herein is meant to be a room where a patient is treated and there may be a source of contaminant present when the room is in use. The source of contaminant may be for example the treated patient or the nursing staff treating the patient. Ex amples of a clean room are an isolation room, an oper ating theater, a patient treatment room or a patient room. It should be understood that these are only ex amples and other kind of clean rooms may also be meant. The present system is configured to provide a (one) combined controlled airflow field in a clean room that may provide substantially uniform cleanness of the in- door environmental conditions in the entire room. They may transport part of contaminants out of a clean treatment area within the room by a jet momentum. They may prevent backflow of the contaminants into the critical zone from the periphery by a jet momentum ad- justment. They may provide the desired air velocity conditions for both contaminant control and thermal comfort for the people in the room. To achieve desired contaminant control and thermal control for the people in the clean room, it is provided a protective air supply system having adjustable air supply flows.

The system comprises a first air supply diffuser and a second air supply diffuser, arranged within a ceiling of the clean room on opposite sides of the clean area and spaced from side walls of the clean room. Each of the supply air diffusers is configured to diffuse a first air flow, having a first air flow volume A 1/s, directed along a ceiling of the clean room and towards the clean area and a second air flow, having a second air flow volume B 1/s, directed along the ceiling of the clean room and towards a perimeter of the clean room. Further, the system comprises a controller cou pled to the air supply diffusers and the controller is configured to adjust the first air flow volume A and the second air flow volume B and their ratio. By con trolling the air flow volumes, it is possible to pro vide different modes for different situations in a clean room, e.g. isolation mode and a normal patient mode which set different requirements for the ventila- tion. Supply air temperature may also be adjusted. The sup ply air temperature may be lower than the room air temperature. The supply air temperature may be for ex ample -3 to -5 °C lower than the room air temperature. The supply air temperature may be adjusted by the con troller. The system may comprise a first temperature sensor configured to measure the supply air tempera ture. The system may comprise a second sensor for measuring the room air temperature. The first and sec ond sensors may be connected to the controller for ad justing the temperature. The controller may be con nected to the estate management system to retrieve da ta of the room air temperature. The supply air temper ature may be lower only in the isolation mode and/or it may be lowered when the isolation mode is enabled. However, the supply air temperature may also be lower in the normal patient mode.

Figures 1 and 2 shows the operation of the system in a normal patient mode. Figure 1 shows a cross section of a clean room from side. The clean room comprises a clean area 1, which is typically around an operating area, e.g. patient bed 10. The clean area should be understood as a three-dimensional space from a floor to a ceiling 4 of the clean room.

The system in figure 1 comprises a first air supply diffuser 2 and a second air supply diffuser 3 arranged within the ceiling 4 of the clean room. The air supply diffusers 2, 3 are located on opposite sides of the clean area 1, as seen in figure 1. The air supply air diffusers may be embedded into the ceiling or they may be installed as a hanging structure so that there is a space between the air supply diffusers and the ceil ing. The first air supply diffuser 2 and the second air supply diffuser 3 are located at a distance from side walls of the clean room. In figure 1, the first air supply diffuser 2 and the second air supply dif fuser is configured to diffuse a first air flows 5, which are directed along the ceiling 4 and towards the clean area 1. The first air flows 5 collides within the clean area and the combined air flow 11 is di rected towards the patient bed 10. This combined air flow 11 flushes the clean area 1 towards the floor of the clean room and further towards exhaust outlets in the clean room.

The air supply diffusers may be provided with multiple nozzles through which the air is diffused into the clean room.

Figure 2 shows the same normal patient mode as figure 1, but in view from above. The first air supply dif fuser 2 and the second air supply diffuser 3 are lo cated at the opposite sides of the clean area 1 around the patient bed 10. The first air flows 5 are diffused towards the clean area.

In normal patient mode, as shown in figures 1 and 2, the thermal comfort of the patient may be provided in most efficient way. The first air flows 5 are merged and the combined air flow is directed downwards to wards the patient bed 10 and the patient. Thus, by ad justing the air flow velocity and the temperature, the thermal comfort of the patient may be easily adjusted. After the combined air flow A+B has reached the pa tient and the patient be, the combined air flow 11 scatter and the scattered air flows are directed away from the clean area 1 and towards the exhaust air in lets.

Figures 3 and shows the operation of the system in an isolation mode comprising all the features of the nor mal patient mode as described above and additionally more air flow are provided. As seen in figure 3, which is a cross section of the clean room like figure 1. The first air supply diffuser 2 and the second air supply diffuser 3 are now configured to diffuse a sec ond air flows 6, which are directed along the ceiling

4 and towards the perimeter of the clean room, i.e. towards the side walls. The second air flows 6 are di rected in opposite direction than the first air flows

5 in each air supply diffuser 2, 3.

In isolation mode, the first air flows 5 and the com bined air flow 10 acts as in normal patient mode. How ever, the second air flows 6 are directed downwards after they have reached the side walls of the clean room. When the second air flows reach the floor of the clean room, they are directed towards the clean area 1 of the clean room. However, they do not reach the clean area 1 as the scattered air flows from the clean area are directed against the second air flows and they merge before the second air flows reach the clean area 1. The merged air flow is directed upwards out side of the clean area 1.

The air supply volume and the ratio of the first air supply flow 5 and the second air supply flow 6 may be adjusted by a controller 7, which is coupled to the first air supply diffuser 2 and the second air supply diffuser 3. The connection may be wired connection, or it may be wireless connection such as WIFI, Bluetooth or connection using radio frequencies.

The controller 7 has a central role in the operation of the system. Structurally and functionally it may be based on one or more processors configured to execute machine-readable instructions stored in one or more memories that may comprise at least one of built-in memories or detachable memories. The air supply volume, i.e. combined air flow volume A+B, may be for example 0-2001/s. The air supply vol ume may be for example 70 1/s in the normal patient mode and/or 2001/s in the isolation mode.

The controller may be configured to adjust the ratio of the first air flow volume A and the second air sup ply flow volume B between 100:0 and 0:100. Above was described that in normal patient mode, the second air supply flow may be absent, and all air supply is dif fused as the first air supply flows towards the clean area. However, the controller 7 may be configured to adjust the air supply diffusers so that there is also a second air supply flow in the normal patient mode.

The first air flow volume A may be same, e.g. 701/s in normal patient mode and in the isolation mode, while the second air flow volume is increased in the isolation mode.

In order to adjust the air supply flow between the first air supply flow A and the second air supply flow B, at least part of the multiple nozzles 8 in the air supply diffusers may closable. For example, in normal patient mode, the outer nozzles may be closed, and in the isolation mode, the outer nozzles are opened.

The air supply diffusers may be divided in separate air chambers for the first air supply flow and the second air supply flow. In normal patient mode, the chamber for the second air supply flow may be closed and supply air is directed only into the chamber for the first air supply flow. The closing may be achieved for example by a flap which is operable by the con troller 7. Figure 5 shows the first air supply diffuser 2 and the second air supply diffuser 3 in assembled state but the ceiling is not shown. The air supply diffuser may comprise cover panel or several cover panels 9 in which the multiple nozzles are arranged. The system may comprise more than two air supply diffusers so that they are provided in different sides of the clean area. The air supply diffusers may be provided in cir cumferential form so that they are arranged around the clean area as shown in figure 6. Figure 6 shows four air supply diffusers 2, 3, 22 and 33 assembled within the ceiling in circumferential form.

It should be understood that one air supply diffuser may be formed of many smaller air supply diffuser com ponents forming one longer and/or wider air supply diffuser. Further, it should be understood that air supply diffusers may be connected to each other so that they form integrated structure.

The air supply diffusers may be provided within the ceiling so that only cover panel or panels 9 are ex posed into the clean room as shown in figure 6.

Figure 7 shows part of the air supply diffuser having multiple nozzles 8. The nozzles are located in a cover panel 9 which is fastened to the air supply diffuser, the form and size of the cover panel may vary. The nozzles may have also different shapes and sizes. The nozzles may be elongated gaps, or they may be circular as shown in figure 7. Other forms like rectangular and triangular may also be used. The nozzles may be ad justable so that the air flow diffused through them may be directed in different directions which enable a flexible throw pattern adjustment of the air supply. The front panel 9 may be provided with slotted open- ings. The nozzles may comprise guiding leaves to ad just the direction of the air supply flow.

Although the invention has been the described in con- junction with a certain type of system, it should be understood that the invention is not limited to any certain type of system. While the present inventions have been described in connection with a number of ex emplary embodiments, and implementations, the present inventions are not so limited, but rather cover vari ous modifications, and equivalent arrangements, which fall within the purview of prospective claims.