GB2309387A - An autoclave - Google Patents

Abstract

The autobath is an apparatus which can act as an automatic mini autoclave or as an electric water bath. It is fitted with a thermostat (10) having a temperature range from 30-100 {C and a timer (12). The process of sterilisation in the autoclave was modified to delete the time of air vent from the chamber, while maintaining at 121{C for a period of 20 minutes. In such case, the conditionally equivalent pressure will be 1.4kg/sq.cm or at 134{C for 3 minutes. Deletion of air vent allows for an absolutely noiseless process if the autoclave is left for self cooling. The autoclave is provided with a safety valve (15) that controls the sterilisation process and could be also used for rapid evacuation of the steam from the chamber after sterilisation. The second function of the autobath lies through its possible utilisation as an electric water bath due to its suitable small size. The incubation time at any predetermined temperature is governed by the thermostat and the electric timer.

Description

A Dual Function Automatic Autoclave This invention relates to sterilisation technology. The increased susceptibility to infection by different microorganisms (particularly hepatitis viruses and AIDS) has greatly encouraged the need for a speedy, small sized, cheap apparatus that would be simply used without any attention by the operator. The automatic autoclaves can only fulfill the last suggested advantage. They are of high cost, large or moderately sized and the time consumed for the removal of air from the chamber takes from 13 to 17 minutes.

For an aim to fulfill the above mentioned specified requirements, the current invention is dedicated. Most importantly it has a dual function. Beside its utilisation as an autoclave, it can be also used as a water bath at any predetermined temperature from 30 - 100 OC.

Another advantage of the invention is that it secures a complete sterilisation without any steam noise (Noiseless autoclave). Such type of autoclave can be used even in the intensive care unit without any disturbance. The new invention gains its noiseless sterilisation technology due to a minor modification of the process, where the period of air vent is omitted. This new technology of sterilisation is achieved by maintaining the articles to be sterilised at a temperature of 121 OC by means of a thermostat, regardless of freeing the autoclave from air. Such temperature is experimentally equivalent to 1.4 kg/sq cm gauge pressure.

The sterilisation process is continued for a period of 20 minutes as controlled by the electric timer that is only allowed to start after the reach of the required temperature in the chamber. As the suggested autoclave is temperature controlled by a thermostat, it is not absolutely necessary to vent the air from it, for thecorrect temperature will be reached and maintained saturation will always occur due to the reserve of water present.

Although it is a well known fact that venting decreases the risk of pockets of air remaining between or within the objects to be sterilised, it is unlikely that this would occur in the mini autoclave due to its very shallow depth. In addition, experimental proof has been achieved by us when folded muslin was put at the theoretical lowest temperature of the autoclave, together with empty cotton-plugged or non-plugged test tubes, containing sterilisation indicator tapes. All were found to be successfully sterilised by the newly suggested method. In addition, cotton plugged test tube containing 3 ml of resistant spore suspension having 109 cells/ml was placed at the same position and was found to be sterile.

Detailed description of an example of the invention "TheAutobath ": The autoclave water bath (The autobath) is illustrated in Figure 1. It is an instrument with a dual function working as a mini autoclave and as a water bath. It works under the following specifications: 1- Chamber (1): Made up of polished stainless steel (1 mm. thickness), withstands three times the amount of the used pressure (5 gauge pressure). It is supplied with a perforated tray (2) for putting the article to be sterilised or a small sterilisation box (3) for surgical dressings or test tubes.

2- Outer body (4): painted enamel, designed to withstand elevated temperatures. The base is covered with perforated circular plate (17) provided with three rubber-screw attachments (5).

3- Lid (6): Thick, pressure resistant cast of aluminium-antimony construction with a nickel polished finish. The lid is provided with a handle for easy transfer (7).

4- Lid lining (8): Durable neoprene rubber lining enables secure lid closure and fitting even when the lining is slightly worn out. The lining can be easily replaced.

5- Fastening screws (9): Five stainless screws fixed with packalite handles. The lid is constructed in a manner that one screw can allow for a flexible movement of the lid to swing horizontally without its detachment from the body of the autoclave.

6- Sterilisation indicators: A thermostat (10) (From 30 to 120 OC, in another models up to 300 OC) which is provided with an indicator lamp (11) is used together with a timer(l2). Sterilisation can be achieved at 121 OC or 134 OC for a period of 20 and 3 minutes respectively. Temperature (13) and pressure (14) indicators are also included. However, as the apparatus works automatically, one or both of them can be omitted. The used timer may be electric that would not start until the required temperature is reached, which is used and is adjusted for the proper time of sterilisation or non electric timer that is adjusted to include the time of the whole process from its beginning up to its end where the apparatus stops automatically without any effort from the operator.

7- Safety valve (15): Counter-weight type controller valve that automatically open when the pressure reaches 2.5 kg/sq cm gauge pressure). The valve will automatically open only under very critical circumstances (when the thermostat is out of order). The same valve can be manually opened for rapid freeing ofthe autoclave from steam after the process of sterilisation to reach the atmospheric pressure (30 seconds).

8- The heater (16): An electric heater inside the sterilisation chamber with 750 - 1200 wt capacity).

9- The conductor: The autoclave is supplied with a conductor for protection of all electric accessones.

Table 1 shows the specifications of the proposed patent.

Table 1. Summary of the specifications=

Diameter of inner chamber 21cm Diameter of the outer body 25 cm Working depth 19cm Complete deptfr 24cm Height to chamber rim 33cm Weight less than 12kg Electricity (heater source) Type sheathed heater, 0.8-1.2kw (220 v 1.5kw Maximal consumption) Automatic timer One to two hours capacity dilitionalparts Circular perforated tray (ididonalparts (on request) 1- A small capacity sterilisation box (3). Test tube rack (18).

2- Manemeter or thermometer or both. (not included in some models.

The autobath is smaller than the Japanese autoclave GV-979 (a non automatic small sized autoclave 15cm diameter and 38cm depth.

The autobath has the advantage over all used automatic and non-automatic autoclaves in carrying all the processes of sterilisation without any noise (except the last step of steam exhaust). It can be made absolutely noiseless by waiting the autoclave for self cooling. In that case it is unlikely that negative pressure would occur due to the fact that the autoclave has not been previously freed from the air.

IN ADDITION IT IS THE ONLY TYPE OF AUTOCLAVE DESIGNED TO BE USED AS A WATER BATH BEING A MINI size AND COULD BE SIMPLY CONTROLLED WITH ITS INCLUDED THERMOSTAT AND TIMER.

INSTRUCTIONS FOR USERS A MINJAUTOCLAVE 1 Distilled water is added to the required level (between minimum and maximum marks).

2 Articles to be sterilised are put on the perforated tray or inside the sterilisation box and the autoclave is tightly closed by the fastening screws using handles.

3 Adjust the thermostat to the required temperature 121 or 134 OC 4 Switch on the heater knob and adjust the timer to the required period of the whole process (heating and sterilisation time approximately 3845 min at 121 OC, and the operator will be familiar with the exact time after few cycles of sterilisation).

5 After the required time, the autoclave will automatically stop. The operator may have the choice either to open the safety valve for rapid cooling and reaching the atmospheric pressure (in such a case the familiar noise of the autoclaving process from steam exhaust will stay for 30 sec), or to leave for self cooling without any fear of any negative pressure.

6 Open the lid and take the already sterilised articles.

INSTRUCTIONS FOR USING AS AN ELECTRIC WA TER BA TH Adjust the level of water from using as a water bath.

2 Adjust the thermostat to the required temperature.

3 Put the articles to be maintained in the water bath on the perforated rack.

4 Maintain for the required temperature for the specified period by adjusting the timer.

N.B. : IT IS PREFERABLE TO PUT A MERCURIC THERMOMETER AND A MERCURIC THERMOREGULATOR IN THE WATER BATH FOR ABSOLUTELY ACCURATE ADJUSTMENT OF THE REQUIRED TEMPERATURE. THIS MUST BE FOLLOWED BY SWITCHING OFF THE THERMOSTAT AT THE REQUIRED TEMPERATURE.

Claims (3)

1 A dual function apparatus acting as an automatic, mini-autoclave and a water bath with a temperature range from 30-150 OC. (or any size or material)

2 A dual function apparatus acting as an automatic mini autoclave and a water bath, with absolutely noiseless, speedy and new autoclaving process in the field of sterilisation technology by automatic maintenance of the temperature at 121 OC or 1.4kg/sq cm gauge pressure without freeing the air from the autoclave chamber for a period of 20 min.or at temperature of 134 OC for a period ofthree minutes.

3 The noiseless and rapid technology of sterilisation by omitting the air vents period.