FI64741C - FOERFARANDE FOER STERILIZERING AV VAERMEKAENSLIGA INSTRUMENT SJUKHUSAPPARATER OCH DYLIKT MED AONGA AV LAOG TEMPERATUR OCH FORMALDEHYD - Google Patents

Description

64741

Method for sterilizing heat-sensitive instruments, hospital equipment, etc., with low-temperature steam and formaldehyde For the sterilization of heat-shrinkable instruments, skimmers, apparatus and devices with a temperature of the formaldehyde

The invention relates to a method for sterilizing heat-sensitive objects, such as instruments, hospital equipment, etc., in which the objects to be sterilized are placed in a chamber and the chamber walls are heated to a desired temperature, in which the articles to be sterilized are sterilized with formaldehyde and low temperature steam. pre-vacuum, introducing a pulse of formaldehyde into the chamber and creating a vacuum in the chamber, repeating the previous method step at least once by introducing a new pulse of formaldehyde into the chamber and creating a vacuum in the chamber; so that when the desired pressure is reached in the chamber, the supply of steam to the chamber is stopped.

15 Heat-sensitive objects, such as ‘e.g. instruments, hospital equipment, etc. cannot be sterilized in conventional autoclaves with high-temperature steam. Heat-sensitive instruments have been known to be sterilized in principle for a very long time by a known method using low-temperature steam and formaldehyde. With regard to the state of the art, reference is made, for example, to the following references: Nordgren, G. (1939) Acta. path, Microbiol. Scan., Suppl. 40. and Alder, V.G., Brown Anne M., and Gillespie, W.A. (1966) J. elin. Path. 19, 83.

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With regard to the state of the art, reference is also made to FI patent application No. 783129, which discloses a sterilization solution with low-temperature steam and formaldehyde. The disadvantage of this known solution is that it is not possible to remove residual formaldehyde. Excess formaldehyde remaining on the surfaces of the articles to be sterilized must, of course, be wiped off, so that the articles can no longer be considered sterile.

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No satisfactory solution has been found to eliminate the drawback described above. If only low-temperature steam were used, such a solution would not achieve a satisfactory sterilization result. On the other hand, formaldehyde alone is not sufficient to obtain a reliable sterilization result, but the achievement of a good sterilization result requires the use of steam.

It is an object of the invention to provide an improvement on previously known methods. It is an object of the invention to provide a method in which a reliable sterilization result can be achieved at a relatively low temperature. It is a more detailed object of the invention to provide a method in which harmful residual formaldehyde is reliably removed from the sterilization chamber and thus a safe sterilization result is achieved.

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The objects of the invention are achieved by a method characterized mainly by maintaining a substantially constant temperature in the chamber walls, including the door, by circulating fluid flow, slightly higher than the selected steam pressure sterilization temperature, and maintaining at least a small outlet from the chamber throughout the process. while flowing out, at the same time effectively flushes the formaldehyde in the chamber out of the chamber.

Other features of the method according to the invention are set out in claims 2-4.

The method according to the invention achieves a very reliable sterilization result and even at a relatively low temperature. In the method according to the invention, Kek-30 has been found to allow formaldehyde alone to act on the goods to be sterilized first, whereby the bacterial spores in them are also weakened. A steam jet is then given, which performs the final destruction of bacteria and spores. In the method according to the invention, a completely reliable sterilization result can be achieved at a temperature as low as, for example, 63 ° C, while the temperature range generally used in previously known methods has been about 70-80 ° C. In the solution according to FI-3 64741 patent application No. 783129 referred to above, a temperature as high as 80 ° C has been used.

The invention will be explained in detail with reference to the principle solution shown in the figure of the accompanying drawing, to which, however, the invention is not intended to be exclusively limited.

In the embodiment according to the figure, objects to be sterilized, such as instruments or hospital instruments, are placed in the chamber 1.

The chamber 1 is provided with a door 2, which is preferably slidably movable to open and close the chamber, respectively. In order to obtain the best possible tightness, the door 2 is sealed with seals 4 with respect to the chamber 1. The chamber 1 is surrounded by a jacket 3 and the door 2 is provided with a jacket 5 and the jacks 15 3 and 5 are adapted to flow a fluid flow heating the chamber 1 and the door 2, respectively. In this embodiment, the device comprises a heat source 7 with a stability of ± 1 ° C. The pump 6 is adapted to suck the heating liquid from the heat source 7, the temperature of which is e.g. 64 ° C, along the tubular connection 13 and to press the heating liquid along the tubular connection 10 into the casing 5 of the door 2.

The liquid heating from the casing 5 of the door 2 continues to flow down the tubular connection 11 to the casing 3 of the chamber 1 and circulate the casing 3 and return along the tubular joint 12 back to the heat source 7. The device thus has a uniform temperature at every point of the chamber 1 including the door 2. In order to eliminate heat losses, the jacket 3 of the chamber 1 is surrounded by insulation 8 and, correspondingly, the jacket 5 of the door 2 is provided with insulation 9.

The device also has a special way of introducing formaldehyde into chamber 1.

Formaldehyde is about 38 Z as a formalin solution in a vessel 15, from which the formalin solution 3 flows through the heat exchanger 16 all the way to the tubular compound 14 into the chamber 1. In this embodiment the heat exchanger 16 is designed so that steam is arranged to flow through the inlet pipe 17 to the heat exchanger down the helical tube and causes the formalin to evaporate, with gaseous formaldehyde flowing into the chamber 1 along the tubular compound 14. Reference numeral 18 denotes a return tube up to which the condensed water flows out of the heat exchanger 16.

The steam inlet pipe is denoted by reference numeral 19. In this embodiment, the inlet pipe 19 is connected to the tubular connection 14. The steam inlet pipe 19 is provided with a valve 21. Reference numeral 20 denotes a valve in the tubular connection 14. The lower surface of the chamber 1 is preferably made slightly inclined, as shown in the figure of the drawing. The chamber 1 communicates at its lower part with an outlet pipe 22 provided with a control valve 23. Reference numeral 24 denotes a vacuum pump and reference numeral 25 denotes a pressure sensor located inside the chamber 1.

The operation of the method according to the invention is as follows. The objects to be sterilized are placed in the chamber 1 and the chamber 1 is sealed by a door 2. The temperature T of the walls 1 of the chamber 1, including the door 2, is constant throughout and the temperature T is generally kept at a temperature about 1-2 ° C higher than the selected sterilization temperature T <. A vacuum, i.e. a pre-vacuum, is provided in the chamber 1 by means of a vacuum pump 24. Next, a pulse of formaldehyde is introduced into the chamber 1, in this embodiment evaporated as about 38% of the formalin solution, and a vacuum is created in the chamber 1. Next, the method step described above is repeated by introducing a new pulse of formalin solution into the chamber 1 and aspirating a vacuum into the chamber 1. If necessary, the method step described above is repeated a sufficient number of times. Generally, during the formalin solution pulses described above, about 1/4 of the total amount of formaldehyde is introduced into the chamber.

In the next step of the method, most of the vaporized formalin solution, i.e. about 3/4, is introduced into the chamber 1. Steam 30 is then introduced into the chamber 1 via the inlet pipe 19 and the steam supply is controlled by the pressure sensor 25 so that when the desired pressure p is applied to the chamber 1. by closing the valve 21. The temperature of the steam corresponding to the pressure p should be slightly lower than the temperature T of the chamber walls.

If the pressure in the chamber 1 falls below the desired pressure p, new steam is introduced into the chamber 1 via the inlet pipe 19.

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In the method according to the invention, the outlet pipe 22 is kept slightly open during the whole process by means of the control valve 23, whereby the condensate, when continuously flowing out of the chamber 1, at the same time effectively rinses the formalin residues out of the chamber 1.

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In the method according to the invention, it is advantageous to operate in the middle of the steam conduction gear by opening the control valve 23 of the outlet pipe 22 more open, whereby the steam flushing effect is enhanced. This operation naturally requires that more new steam must be introduced into the chamber 1 up to the inlet pipe 19. Increasing the steam supply is easy to implement by adjusting the valve 21 more open.

In the final step of the method according to the invention, a vacuum is sucked into the chamber 1 and filtered air is introduced into the chamber 1, and this operation is repeated a sufficient number of times.

In the method according to the invention, it has been found that the formaldehyde alone first acts on the objects to be sterilized, whereby the microbes and spores are weakened. After this granulation step, a steam jet is introduced into the chamber 1, which performs the final destruction of bacteria and spores. In this way, a very reliable sterilization result is achieved. Continuous effluent flow ensures efficient removal of residual formaldehyde from chamber 1. The method 25 of the invention allows a sterilization temperature Tg as low as 63 ° C.

and nevertheless a completely reliable sterile warp result is achieved, and formaldehyde-free sterilized objects.

Only the basic solution of the invention has been described above, and it will be clear to a person skilled in the art that it can be modified in numerous different ways within the scope of the inventive idea set out in the appended claims.

Claims (4)

A method of sterilizing heat sensitive articles, such as instruments, hospital appliances, etc., in which method the items to be sterilized are placed in a chamber (1) and the walls of the chamber (1) are heated to the desired temperature (T), at which method 5 items are to be sterilized is sterilized by means of formaldehyde and low temperature steam and in which process suppression or pre-vacuum is effected in chamber (1), a dose of formaldehyde is introduced into chamber (1) and vacuum is effected in chamber (1), the foregoing the process step is repeated for at least one failure to introduce a new dose of formaldehyde into the chamber (1) and to create a vacuum in the chamber (1), the remainder or most of the formaldehyde being led into the chamber (1) and even further into the chamber (1). and the meadow entry into the chamber (1) is controlled by means of a pressure transducer (25) or the equivalent in such a way that the meadow input into the chamber (1) is terminated when the desired pressure (p) has been achieved in the chamber (1), characterized thereof, that a substantially constant temperature (T) is maintained in the walls of the chamber (1), a door (2) included, by means of a circulating liquid flow, which temperature is slightly higher than a selected steam pressure (p) corresponding to sterilization temperature. (Tg) and at least a small wastewater flow from the chamber (1) is maintained during the entire process, the condensate flowing out of the chamber (1) at the same time effectively flushing the formaldehyde present in the chamber (1). 25 2. A method according to claim 1, characterized in that, substantially in the middle of the initiation stage, the effect of the flushing of the chamber (1) is increased by increasing the effluent flow out of the chamber (1) and 1, respectively. lead a larger input anxiety stream into the chamber (1). 30 3. A method according to claim 1 or 2, characterized in that in the final stage of the process vacuum is created in the chamber (1) and into the chamber (1), filtered air is conducted and this process step is repeated sufficiently many times.