Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
  • A61L2/24—Apparatus using programmed or automatic operation
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
  • A61L2/16—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using chemical substances
  • A61L2/22—Phase substances, e.g. smokes, aerosols or sprayed or atomised substances
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L9/00—Disinfection, sterilisation or deodorisation of air
  • A61L9/14—Disinfection, sterilisation or deodorisation of air using sprayed or atomised substances including air-liquid contact processes

Definitions

• the invention concerns a method of disinfection of the inner surfaces of a room and of articles contained in said room, especially in food producing plants, and comprising several steps of a process, including a step in which the air in the room is supplied with atomized liquid consisting of a disinfectant mixed with or dissolved in water, and that the room after this step remains in this state for a previously determined length of time.
• the invention concerns a plant for the execution of the method comprising a nozzle for atomizing the liquid which nozzle may be provided with disinfectant dissolved in water from a main pipeline connected to a water supply, which main pipeline is connected to a dosage unit which may supply the main pipeline with concentrated disinfectant at a steady proportion in such a way that water and disinfectant will be mixed in the pipeline.
• the invention further concerns an atomization nozzle for use in connection with the method and the plant according to the invention.
• a method and a plant of this type and for use in food producing plants is know from FR published publication no. 2.600.896.
• the known plant which is controlled from a central programmable control unit, sucks up concentrated disinfectant to a liquid inlet for the nozzles by means of an injector of the venturi type, and supplies the mixed liquid to a container from which the liquid is conveyed to an atomizing unit.
• the container is necessary as, due to the venturi injector, it is only at a certain magnitude of the liquid flow that the proportion of water and concentrate will be constant.
• liquid will be sprayed against an impeller or mixer which pulverizes the drops to a size between 15 and 20 micrometers.
• the disinfectant is atomized in a flow of air which carries the drops of liquid around the room to convey the desinfectant into all nooks and corners of the room.
• the object of this invention is to show a method of disinfecting whole rooms which better than the known methods may disinfect all firm surfaces in a room in a more reliable and reproducible way without heating neither the disinfected surfaces nor the disinfectant.
• Another object is to provide a method which makes an automatic disinfection of a room and its furniture possible and thereby saves manpower.
• An additional object of the invention is to provide a simple method of disinfection in which the disinfection may proceed in a cold state, i. e at the temperatures which exist in the room and with liquid which has the same temperature as water from the public water supply.
• a mist of fine liquid drops is created in the room which drops may keep floating for such a length of time that the drops by ordinary dispersion in the air in the room may penetrate into the outermost corners and there condense on all firm surfaces. It turns out that the number of remaining bacteria colonies even in the most difficult places to disinfect, may be reduced to below the allowed marginal values in premises intended for food production.
• An object of the invention also is to show a plant for implementation of the method which plant is designed more flexibly than the previously known plants which demand a central storage container and a dosage pump for each nozzle or group of nozzles if several nozzles are to be employed at various moments, for example in the case of several rooms of different sizes with a resulting need for different rates of flow of disinfectant.
• the dosage unit consists of a volume flow meter inserted in the main pipeline, a control unit and a dosage pump in which the parts are connected in such a way that a signal with the measured value from the volume flow meter may be transmitted to the control unit which depending on the signal may control the speed of the dosage pump.
• the method according to the invention may be implemented as described in claim 2 in which the proces comprises a step in advance of the others in which the air in the room is humidified by atomization of water during a period, at least till the air is saturated with aqueous vapour.
• the proces comprises a step in advance of the others in which the air in the room is humidified by atomization of water during a period, at least till the air is saturated with aqueous vapour.
• a continuous aqueous film is created on all surfaces in the room which film is a kind of carrying medium for the disinfectant.
• the disinfectant in a later step is atomized in the room it may be distributed in the water film and penetrate into the corners of furniture and machinery and into the coatings.
• ejector nozzles driven by compressed air are employed in which the duct for liquid in each nozzle has its mouth outside the nozzle. In this way the maintenance work on the nozzle installations is minimized as calcareous precipitations will be avoided to a large extent. Furthermore, ejector nozzles have the advantage that they may be made self-supplying with liquid, controlled solely by the compressed air supply so that liquid is not running out of the nozzles during standstill.
• the nozzles may in a further step following each atomization step of the process be blown dry by compressed air by closing the water supply as described in claim 6.
• fig. 1 shows in principle a plant according to the invention installed as two different embodiments in connection with rooms that are to be disinfected
• fig. 2 shows a system diagram of the functions of the plant
• fig. 3 is a section of a nozzle for use in connection with the plant
• fig. 4 is a section of the nozzle on the line IV - IV in fig. 3
• fig. 5 shows two nozzles mounted on a common base
• fig. 6 shows the size distribution of liquid particles produced by a nozzle according to the invention.
• a preferred embodiment of the plant according to the invention may be installed in separate rooms 1 and 2 and be built up of main constituents: a dosage unit 3, a control unit 4, a water supply 5, a supply of compressed air 6, slave units 7, and nozzle in ⁇ stallations 8 with nozzles 11.
• the rooms 1, 2 constitute a part of a slaughterhouse ox another food processing plant.
• the invention may be employed in many other types of industry or in other connections where repeated disinfections are required from time to time.
• the dosage unit 3 supplies all the rooms 1, 2 and is therefore placed centrally.
• the dosage unit 3 will normally be supplied with ordinary water under pressure from the public water mains 5 and with concentrated disinfectant from a container 9 for chemicals.
• the control units 4 may as in the rooms 1 be common to several rooms or a control unit 4 may be placed in each room 2 if a period independent control of each room 2 is desired.
• the control units 4 control slave units 7 which receive pure water from water supplies, preferably in the shape of taps for ordinary water which exist beforehand in the rooms 2.
• the number 10 indicates a supply of electric current from the public electricity supply which supplies the control units 4.
• Each slave unit 7 supplies in each room 1, 2 a nozzle installation 8, normally consisting of between two and fifty nozzles, with water and compressed air.
• the water supplies 5 may, as shown in fig. 2, contain a non-return valve 12 to avoid contamination of the water supply, and a filter 13 which detains particles smaller than five micrometers or possibly finer particles.
• the dosage unit 3 may be constructed as shown in fig. 2 which shows an installation which in principle is as in the rooms 1 in fig. 1, but without a control unit 4.
• the dosage unit 3 is supplied with water through a branch 16 from the water supply 5 which water is conducted through a reduction valve 17 which may reduce the water pressure to about 1,5 bar surpressure, and which provides a steady supply at this pressure to the dosage unit 3.
• a manometer 18 for control of the momentary pressure of the water is inserted in the branch 16.
• the substantial parts of the dosage unit 3 are a dosage pump 19 and a volume flow meter 20 which together control the mixing of disinfectant from the container 9 for chemicals with water.
• An eletric impulse generator is mounted on the flow meter 20, which in this case is of the wing wheel type, which generator may send a signal to the pump 19 to regulate its rate of revolution in accordance with the momentary flow of water through the volume flow meter 20.
• a pres ⁇ ostat 21 is connected to the pump and may register if the disinfectant does not flow through the pump 19 during the process. If this is the case a signal is transmitted to the control unit 4 which lights a warning light and possibly stops the process.
• the dosage unit 3 may be designed with an as such known, not shown static mixer or mixing cell placed at or downstream of the place where disinfectant is added to the water. It is thereby ensured that a complete mixing of disinfectant and water takes place.
• the dosage unit 3 also comprises a non-return valve 22 which ensures that disinfectant cannot be forced back into the water supply 5.
• A' pipe switch 23 in the dosage unit 3 further ensures that not too large overpressures arise in the system.
• a second non-return valve 24 mounted in connection with a suction inlet 25 in the container for chemicals 9 prevents disinfectant from flowing back after each dosage, an arrangement which ensures a very stable supply during the starting phase.
• a level meter 26 of the float type is connected to the control unit 4 in such a way that the last-mentioned will receive an electric signal when the container 9 is empty.
• the mixed disinfectant is conducted from the dosage unit 3 through a pipeline 27 to the slave units 7 in which a magnet valve 30, depending on a signal from the control unit 4, controls the supply of disinfectant to the nozzle installation 8.
• the slave unit 7 additionally has two more magnet valves 31 and 32 which control the supply of pure water from the water supply 5 to the nozzle installation 8, also depending on the signals from the control unit 4.
• the slave unit 7 has a pressostat 33 which controls the pressure of the compressed air; if the pressure transgresses the limits of the admissible interval the pressostat 33 will send signals to the control unit 4 which will then disconnect the magnet valves 30, 31 and 32 whereby liquid will no longer be supplied to the nozzles.
• a not shown emergency stop in each slave unit 7 may stop the program in the room which is serviced by the unit 7.
• a shut-off and choke valve 35 is inserted in series with the supply 6 of compressed air which valve besides being able to shut off the air supply during standstill for a longer period may also reduce the pressure to a suitable level, e.g. 5-6 bar above atmospheric pressure.
• An air filter 36 to clean the air for the plant is furthermore arranged. In the preferred embodiment all particles larger than 5 micrometers are detained, but other embodiments with finer filters, for example sterile filters may of course be mounted here.
• a magnet valve 37 which depending on a signal from the control unit 4 may control the active condition during atomization of water or disiffectant from the nozzle installation 8, is provided.
• the control unit 4 which may be placed centrally in the building in which the rooms 1, 2 are placed, controls all the functions of the plant depending on programmed sequences.
• the control unit 4 is based on an as such known electronic programmable control, so called PLC (Programmable Logic Controller) , by which the functioning of the plant may be determined arbitrarily and the conditions in the plant controlled.
• the functions of the plant will just be programmed into the PLC according to the conditions prevailing im each room.
• the PLC may then guide separate slave units 7 and corresponding magnet valves 37 for the compressed air whereby various sequences of disinfection and atomizing of clean water may be controlled with a displacement in time as in the rooms 1. If an individual control of the processes in each room is desired this may be carried out as in the rooms 2 shown in fig. 1, in which each room has one control unit 4.
• the control unit 4 furthermore has a transformer which transforms the grid voltage down to 24 volts AC for the control of magnet valves and signal lamps etc., whereby the employment of certified electricians for the installation of the plant may be avoided. Furthermore, the control unit 4 has a fuse, indicator lamps, which show the program step the plant is working on, switches for starting the disin ⁇ fection program, and switches for starting and stopping the atomization of pure water in the room. Also, the slave units 7 may be disconnected from the control units 4 via one or more not shown relais. Other relais, also not shown, form intermediaries between the PLC and the magnet valves in the plant in consideration of the limited electrical power which the PLC unit may carry.
• the nozzle installations 8 may be designed in two ways, namely as nozzles 11 on pipes as shown in fig. 2, or as nozzles 11 on a base as shown in fig. 5.
• a choke valve 40 in series with the magnet valves 30 and 32 which choke valve is employed in reducing the liquid pressure in process steps in which a very fine atomization is desired.
• the actual nozzle 11 is secured to the tube 41 for compressed air via a rigid connection 42 which contains a conduit for compressed air. Liquid is conveyed to the nozzles 11 from another pipe 43 through a flexible hose 44
• two nozzles 11 are placed on a common base 45 which is provided with pipe stubs 46 and 47 for the supply respectively of compressed air and liquid.
• Compressed air is conveyed through not shown internal ducts in the base 45 to a number of hollow joints 48 which by means of mutual spherical surface connections are both tight fitting and turnable, and provide a rigid base for the nozzles 11.
• the joints 48 are of an as such known type. Liquid may in a similar way be conveyed via not shown internal ducts in the base 45 to the nozzles 11 through ssen hoses 49.
• the base 45 may further be provided with a not shown magnet so that the base may be secured to a steel beam or the like inside factory buildings.
• the advantage of this kind of mounting is that the nozzles may easily be mounted and dismounted in a room, and in addition the nozzle discharge openings 55 may be turned towards each other if a finer atomization than that, which a single nozzle may produce, is desired.
• each nozzle 11 is designed as ejector nozzles and as shown in figs. 3 and 4. Substantially each nozzle 11 consists of a housing 56 and an insert 57.
• the housing 56 is provided with a cylindrical chamber 58 which ends in a plane end surface 59 in the the middle of which the nozzle discharge opening 55 is placed.
• the housing 56 also has a laterally directed opening 60 for the supply of compressed air and provided with a thread.
• the insert 57 is provided with a central duct 61 for liquid which duct 61 at the inlet end is provided with a thread for the mounting of an inlet pipe stub (not shown) , and is in the vicinity of the outlet narrowed down to a smaller diameter.
• the insert 57 is designed with a broad base 62 which secures sufficient tightness for compressed air and a correct distance from the end surface 59 when the external thread of the insert 57 is screwed into the housing 56.
• the insert 57 has a lesser diameter in the area 63 which in the mounted state is placed opposite the opening 60, and a guide part 64 which has a diameter of its circumscribed circle adapted to the chamber 58 and is sectioned into chords in the shape of plane surfaces 65 to ensure the passage of the compressed air.
• the guide part 64 ensures that a stub 66, through which the liquid duct 61 passes, is placed centrally in the discharge opening 55 in consideration of the output of the nozzle 11.
• the annular slit 67 around the stub 66 has a width between 0,1 and 0,2 mm.
• An end surface 68 on the insert 57 is encircling the stub 66 opposite of and at a distance from the surface 59.
• the stub 66 protrudes outside the housing 56 whereby the touching of the nozzle 11 by particles of liquid may be avoided and calcareous incrustations or other contaminations on or in the nozzle 11 are equally avoided.
• the nozzles 11 may be manufactured of various materials. It is preferred that the housing 56 and the insert 57 are produced from machine finished thermoplastics which are (chemically) resistant in relation to the liquids applied.
• the size of the input pressure of the compressed air at the nozzles may be between 0,6 and 8 bar above the atmosphere, preferably between 2,5 and 4,5 bar.
• a distribution of the sizes of particles is achieved at the nozzle according to the invention in which most particles have a diameter less than 5 micrometers and preferably are substantially smaller than 3 micrometers.
• the distribution of sizes of particles is shown in fig. 6 in which the number of particles per liter is shown in relation to the particle diameters in micrometers. The measurements has been undertaken by atomization with a single nozzle according to the invention.
• the method according to the invention may be implemented in the following way.
• duration and type of liquid is adjusted for each step in the process of disinfection.
• a selection is made on the basis of empirical values, which depend on the size of the room, the relative humidity of the air etc., of a duration between 0 and 120 minutes for a first step a) for the atomization of water, i. e. humidifying or "soaking" of the room.
• values of duration of the following steps are adjusted for the following steps, b) for the atomization of disinfectant, c) for pause and possibly d) for the atomization of water, "rinsing" .
• a step e) is programmed for the drying of the nozzles by blowing compressed air through the nozzles without addition of water during 0 to 10 minutes, preferably 60 seconds.
• Known water soluble or diluent soluble disinfectants are atomized in step b) , e. g. disinfectants containing benzalconium chloride, hydrogen peroxide, sodium hypochloride, peracetic acid or alkyl aminos.
• step a) a sufficient amount of water is atomized to saturate the air with aqueous vapour and a mist of water particles is formed.
• the vapour condenses and the water precipitates on all solid surfaces in the room and forms a continuous film on the surfaces.
• step b) disinfectant is atomized in the same way till a dense mist of water particles containing dissolved chemicals floats in the room. The disinfectant precipitates in the same way on the surfaces in the room.
• step c) disinfectants are active for such a period that all germs will be killed.
• Step d) functions as a rinsing process in which the chemicals are again removed from the surfaces .
• the whole process may be started by activating a switch on the control unit 4, f. inst. when the manual cleaning is finished, or by a time switch in such a way that the plant starts automatically after working hours.
• the control unit 4 further has a function in which, by activation of a second switch, a humidification step corresponding to step a) may be performed before a manual cleaning.
• a humidification step corresponding to step a
• the invention is chiefly intended for slaughterhouses, fish factories and other meat processing plants, in dairies, breweries and other food processing plants, but other possible applications may be imagined.
• the invention may be implemented in other ways than described above within the scope of the claims.
• the method according to the invention may be implemented with ready- mixed disinfectant in stead of the continuous mixing as described in the preferred embodiment.
• Other types of nozzles may f. inst. be employed, including other types of ejector nozzles.
• Pipe connections etc. may also be designed in other ways in the plant.
• the invention may be implemented with mobile units, in which several of the main components of the plant were integrated, for use in successive disinfection of various rooms.

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• Health & Medical Sciences (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Apparatus For Disinfection Or Sterilisation (AREA)

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Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (22)

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Citations (8)

• 1989
  • 1989-04-14 DK DK180389A patent/DK162141C/da not_active IP Right Cessation
• 1990
  • 1990-04-11 DE DE4090663A patent/DE4090663C2/de not_active Expired - Fee Related
  • 1990-04-11 DE DE19904090663 patent/DE4090663T/de active Pending
  • 1990-04-11 WO PCT/DK1990/000092 patent/WO1990012600A1/en active Application Filing
  • 1990-04-11 AU AU55279/90A patent/AU5527990A/en not_active Abandoned

Patent Citations (8)

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