Gas separation: processes – Filtering
Reexamination Certificate
2002-08-19
2004-11-02
Spitzer, Robert H. (Department: 1724)
Gas separation: processes
Filtering
C055S356000, C055S473000, C055SDIG002
Reexamination Certificate
active
06811593
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an air-cleaning device for air cleaning in sensitive environments such as operating rooms, drug manufacture, micro-chip production (processing industry) and similar areas. The present invention also concerns a use of an air-cleaning device. The present invention also relates to a method of producing an air-cleaning device
BACKGROUND
Ventilation with efficient removal of particles has become more and more important in sensitive environments such as e.g. operating rooms, drug manufacture, micro-chip production (processing industry) and similar areas. It has been chosen to exemplify by pointing to the problems concerning surgical operations and the concrete problem associated with the environment in operating rooms.
There is a continual development towards reducing the risk of being infected during operations related to surgery, which results in human suffering and heavy expenses for the society. Among the most critical operations are the orthopedic, where the risk of subsequent infections is considerably increased if the surrounding air, personnel and instruments cannot offer a very high purification level. In recent years, a lot of research has been done on the impact of air during different types of operations. The performed studies show that already after about 30 min the surrounding air is so contaminated with bacteria-carrying particles that the risk of infection is increased by several percent, even if everything present in the operating room at the beginning of an operation is sterilized.
The problem is largely due to the fact that the operating personnel is moving and emits different kinds of particles from e.g. skin and textiles. There are a number of different air-cleaning solutions and ventilation systems offering a very high air quality without placing too much burden on the personnel. One of the most efficient ways is a laminar-flow ceiling with an HEPA-filter (High-Efficiency Particulate Air filter) which cleans the incoming air with 99.9997% confidence. The system is often used in particular in operating rooms and is also referred to as “clean-air ceiling”. The system creates a laminar airflow (LAF), i.e. the entire air mass in a defined area is moving with the same velocity in parallel lines and with a minimum of disturbances. The optimal air velocity for such a system is 0.3-0.4 m/sec to avoid disturbing turbulence to as great extent as possible while removing airborne particles. The laminar airflow can be provided vertically or horizontally. The above-described system has contributed to reducing the number of infections during e.g. hip-joint operations by about 8%. The system is ventilating in an advanced way, whereby between 15-20 changes of air per hour are required according to Swedish regulations,
The system is a comparatively expensive ventilation alternative. The installation cost amounts to about 2 million SEK, which explains the limited number of installations/hospital. The system is non-optimal in the sense that there are always disturbances in the laminar airflow between the ceiling and patient, such as an operating lamp, the heads of the operating personnel, and various equipment hanging from the ceiling. These disturbances create turbulence in the airflow, which may result in particles being left in the critical area and thereby constituting a risk. Measurements have also been performed in order to map the positions of the operating personnel around the operating table. In several cases, the personnel have been shown to be standing in the way of the streaming air.
The conclusion is that every type of operation in an LAP has to be carefully studied as for the relation between air-stream, personnel and instrument table. To sum up, the described system, laminar-flow ceiling with HEPA-filter, can be said to work well as ventilation in the operating room but it does not guarantee a sufficiently clean air over the operating table (patient) and the instrument table as people start moving around and emitting contaminated particles. The described problems make the prevailing systems sensitive to surrounding factors and therefore the air cleaning does not provide the aid it aims at.
One problem is the throughput in an operating room. Placing a patient in the operating room leads to a very high bacterial contamination of the air and arranging the instruments at the same time is therefore highly inappropriate. This results in unnecessary waste of time during switching between operations (every single minute is precious). A problem associated with fixed equipment (ultra-clean rooms) is that it is difficult for the operating crew not to stand in the way of the clean air.
DE-C1-4014795 concerns an air-cleaning device for operating rooms comprising a laminar-flow ceiling with HEPA-filter. As can be seen from the drawing, a cleaned airflow leaves the laminar-flow ceiling. The laminar airflow is thereafter disturbed between the ceiling and patient by an operating lamp. The disturbance may create turbulence in the airflow. Part of the airflow is allowed to pass through a channel in the lamp by means of a fan arranged therein. In this way, an overpressure is created in the operating room and the airflow passing in the operating lamp has a different velocity compared to the airflow from the laminar-flow ceiling. There is no air-cleaning in the lamp. The operating lamp is fixed to the laminar-flow ceiling and operations therefore have to be performed in the very proximity of the installation.
U.S. Pat. No. 5,225,167 relates to a fixed air-cleaning device comprising an HEPA-filter. The air-cleaning device does not include a screen with pressure-fall increasing means to provide a laminar/low-turbulent airflow.
DESCRIPTION OF THE INVENTION
The present invention aims at minimizing the above-mentioned drawbacks according to the state of the art. An object of the present invention is to achieve a user-friendly, reliable and cost-efficient device, which is able to clean and distribute air in the most critical environments with a highly limited impact of outer factors such as people in movement or equipment. Thereby, a broader object of the present invention is, among other things, to achieve an air-cleaning device which enables distribution of a clean, low-turbulent/laminar airflow in sensitive environments (such as for instance above an operating table) and distribute the airflow over a specific area (e.g. an operating area or an area for application of micro-chip components) without the airflow being disturbed by personnel or equipment in the room. Furthermore, the intention is to achieve a flexible air-cleaning device with an air-distributing screen, which ensures a low-turbulent/laminar airflow while presenting a simple design being uncomplicated to use and easy to clean. A further object is to provide an air-cleaning device, which is cost efficient for sensitive environments.
The solution is achieved by an air-cleaning device with the characterizing features of claim
1
. More specifically, claim
1
according to the present invention relates to an air-cleaning device for air cleaning in sensitive environments such as operating rooms, drug manufacture, micro-chip production (processing industry) and similar areas. The air-cleaning device comprises a clean-air assembly with an inlet, through which air is sucked in from the ventilated room by means of a fan arranged in the clean-air assembly. The clean-air assembly further comprises an air duct which is adjustably arranged, said air duct transporting the air from the clean-air assembly to an exhaust-air distributing unit, arranged at the clean-air assembly. To said unit, a screen for clean-air distribution is arranged, the screen comprising at least one pressure-fall increasing means. The means for increasing pressure-fall ensures that the velocity of the exhaust air is leveled out and distributes a low turbulent or laminar airflow. In the air-cleaning device is further arranged at least one filter for air cleaning. The air-cleaning device is a unit arranged to be mobile in t
Hansson Tomas
Hörnqvist Ulf
Birch & Stewart Kolasch & Birch, LLP
Spitzer Robert H.
Toul Meditech AB
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