Ventilation – Clean room
Patent
1996-08-21
1998-11-03
Joyce, Harold
Ventilation
Clean room
454192, F24F 900
Patent
active
058300589
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a ceiling-mounted ventilation system assembly, where ventilation air from the ventilation system is directed down towards a working area, and where the ventilation system is supplied with air from the indoor air and/or from external ventilation equipment, where the ventilation system is divided into at least two mutually separate air sections, where at least one of the sections is designed and positioned such that airflow therefrom will primarily strike a zone of activity in a working area, whilst the other section or sections are designed and positioned such that the airflow therefrom will strike areas outside the zone of activity, and where each of the said sections is equipped with means to control the volume of air passing through the section, means for controlling the temperature issuing from the section, and means for ensuring a determined purity of the air that is emitted.
The invention may be used in particular in connection with operating theatres in hospitals, although it is not necessarily limited to this application.
2. Prior Art
The purpose of ventilation in an operating theatre is to limit the risk of surgical incisions formed in the patient undergoing an operation being exposed to airborne impurities from unsterile sources. Air ventilation is also essential for the removal of any anaesthesia gases which may permeate the air in the operating theatre.
Compared with conventional turbulent ventilation, vertical, essentially parallel flowing, preferably one-way, downwardly directed airflow and with a more outwardly directed airflow in large parts of the marginal areas can to a considerable extent reduce the number of infections. The advantages of an air exchange system for the whole operating theatre have proven to be particularly favourable. With airflow of this kind, the entire air mass will circulate in one direction and displace the existing air in the operation area. The first essential step for such laminar airflow takes place when incoming air is expelled straight down through microfilters above the operating table. This airflow prevents air masses from becoming mixed in the working area and the air is changed several hundred times per hour in the actual operating zone and somewhat fewer times in the remaining area of the operating theatre.
Furthermore, it is usual that a portion of the total air, e.g., 20% is filtered out of the room and is replaced by fresh air, whilst about 80% of the air in the room circulates, is filtered with replacement air and expelled back into the room. In this way, increased quantities of fresh air will not be needed, which is energy-saving in comparison with the conventional systems.
Ventilation systems of the aforementioned type are supplied by the Finnish company Kojair, among others.
A second known system is supplied by the British company Ollerton Laboratories under the trade mark "OMNIFLOW". According to this known system a positive airflow will be provided and where in the ventilation system a negative ionization system may optionally be provided which, by affecting the air issuing from the ventilation system, will cause a reduction in tiredness and an increase in the power of concentration among the personnel in the operating theatre. Furthermore, this known system makes known that a reduction in airflow brings about a reduction in air treatment at the site of the operation. This is due to convection heat from surgical lamps, the patient and so forth Moreover, four blow-out quadrants create problems of striking accuracy in relation to the zone of activity on the operating table.
By way of elucidating the prior art, mention can be made of Swedish Patent 419126 which concerns a solution where the division into zones does not allow for a variable function and, in addition, temperature control is problematic.
British Patent 1127793 relates to a use of an "air curtain", which in a operating theatre environment is a risk because there is a danger that particles may be broke
REFERENCES:
patent: 3023688 (1962-03-01), Kramer, Jr.
patent: 3068775 (1962-12-01), Zehnder
patent: 4094232 (1978-06-01), Howorth
patent: 4137831 (1979-02-01), Howorth
patent: 4856419 (1989-08-01), Imai
AET Arbeidsmilj.o slashed. og Energiteknikk A/S
Joyce Harold
LandOfFree
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