Chemistry: molecular biology and microbiology – Apparatus – Including measuring or testing
Reexamination Certificate
1998-11-04
2001-09-25
Beisner, William H. (Department: 1744)
Chemistry: molecular biology and microbiology
Apparatus
Including measuring or testing
C435S287900, C435S288300, C435S309100, C073S028050
Reexamination Certificate
active
06294375
ABSTRACT:
The present invention relates to a microbiological pressurised gas control device.
One particularly beneficial application of the invention is the control of compressed air or oxygen for example circulating in a network, such as a network supplying surgical or treatment units in hospitals, or clean rooms used in the pharmaceutical and cosmetic industries and in the agro-food industry.
Microbiological control devices for environmental air using the principle of impaction are already known.
In these known devices, a Petri dish placed facing an impaction plate pierced with numerous small holes, subsequently called a “filter”, is used to collect the dust particles contained in the environmental air which is aspirated by a pump through the perforations of the filter, the jets crossing through the perforations of the filter being projected onto the nutrient medium of the Petri dish.
The micro-organisms contained in the dust impacted by the jets of gas onto the nutrient medium, multiply and produce colonies if the nutrient medium is suitable. After several days of incubation, these germs are therefore replaced by visible colonies of which some can be identified by the naked eye.
The control of a pressurised gas using known devices requires prior pressure release of the gas initially compressed at several bars, which usually leads to a sonic burst followed by a shock wave. These sharp variations in gas pressure cause the destruction of the micro-organisms contained in the dust particles carried by the gas. Measurements taken on the released gas are therefore not representative measurements of the biocontamination of said gas.
The present invention describes a new microbiological control device for a pressurised gas carrying dust particles, without causing the total or partial destruction of the micro-organisms contained in said dust particles.
More particularly, the device of the invention comprises collection means for collecting said dust particles contained in the pressurised gas, said collection means being placed in an inner cavity fitted with a gas inlet and a gas outlet, and in which the prevailing gas pressure is, at least during the operation of said device, equal to the pressure of the gas carrying dust particles entering said cavity.
Therefore, such device may advantageously be directly connected to a supply network of compressed gas, or to the outlet of a container containing such gas.
According to one beneficial characteristic of the device according to the invention, it comprises a sonic nozzle positioned at the exit of said cavity, downstream from said collection means.
Said sonic nozzle is used to release the pressure of the gas that is pressurised in said device, reducing it to atmospheric pressure while maintaining constant volume flow. This is advantageous as, regardless of pressure, the device of the invention can achieve identical volume flow at impaction level.
Needless to say the diameter of the sonic nozzle can be adapted in relation to desired volume flow.
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Chevalier Christophe
Chevalier Philippe
Beisner William H.
Chevalier Christophe
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Ultra Propre Nutrition Industrie Recherche (U.N.I.R.)
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