GB2335600A - Chemical sterilising apparatus. - Google Patents

Abstract

The chemical sterilizing apparatus mixes sterilizing solution in a tank (4) using mains water and a reagent, the tank (4) being separated from the mains water inlet by an air break. A part of the sterilising solution is supplied to a sterilizing chamber (10) through a misting nozzle part (11A) to generate a mist of sterilizing solution within the sterilizing chamber (10) to sterilize all of the internal surfaces of the sterilizing chamber (10).

Description

CHEMICAL STERILISING APPARATUS 2335600 This invention relates to chemical

sterilising apparatus and particularly to chemical sterilising apparatus of the type used to sterilise medical and laboratory instruments.

A variety of chemical sterilising apparatus employing a number of different sterilising methods are known. Chemical sterilisation apparatus can be used to sterilise most medical and laboratory instruments and is particularly used for sterilising instruments which cannot be safely heat sterilised using hot steam or hot air sterilising apparatus.

A significant problem associated with many known chemical sterilising apparatus is that they employ chemicals which are hazardous to human health and that they do not allow a variable amount of sterilising fluid to be produced, relying on fixed volumes of chemicals and solvent mixed to form a sterilising solution.

Furthermore, known sterilisation apparatus are difficult to operate and run a significant risk of performing ineffective sterilisation by successive dilution of generated sterilising solutions or contamination of rinsing fluids such as water, that are used to remove sterilisation solution from sterilised objects.

Further disadvantages of known sterilisation apparatus are that they are expensive to operate, requiring excessive amounts of sterilising solution to be produced, rather than a specific amount for a specific task, and that many require hand pouring of dangerous chemicals with a significant risk to health.

Further, in known sterilising apparatus, the time for which the instruments are exposed to the sterilising solution is controlled by the operator. This can result in the instruments being exposed for an excessive amount of time, leading to chemical damage to the instruments from the sterilising solution.

A further disadvantage of known chemical sterilisation apparatus is t hat they are not capable of employing the sterilising solutions used to sterilise instruments for sterilisation of components of the apparatus themselves. As a result, it is necessary to carry out the regular sterilisation routine on the 1 sterilising apparatus itself in order to ensure that the sterilising apparatus does not become contaminated by bacteria or other micro- organisms, which could result in contamination of the sterilised objects by said micro-organisms after they have been sterilised.

The apparatus of the present invention is directed towards solving the above problems.

In a first aspect, this invention provides a chemical sterilising apparatus comprising:

a sterilising chamber in which objects to be sterilised are placed; tank; first supply means for supplying a predetermined amount of a first reagent to the tank; means for supplying a predetermined quantity of water to the tank through an air break to combine the reagent with water for forming a sterilising solution; and means to supply the sterilising solution to the sterilising chamber.

In a second aspect, this invention provides a chemical sterilising apparatus comprising:

a sterilising chamber in which objects to be sterilised can be placed; a first supply means for supplying a predetermined amount of a first reagent; means for combining the reagent with a predetermined quantity of water to form a sterilising solution and supply it directly to the sterilising chamber; means to circulate sterilising solution from the sterilising chamber through a filter able to block the passage of micro-organisms; and means to supply rinsing water to the sterilising chamber through the filter.

In a third aspect, this invention provides a chemical sterilising apparatus comprising:

a sterilising chamber in which objects to be sterilised are placed; a misting nozzle; and means to supply a sterilising solution to the sterilising chamber through the misting nozzle such that all internal surfaces of the sterilising chamber are contacted by the sterilising solution.

Examples of the present invention will now be described by way of example only with reference to the accompanying diagrammatic figures, in which:

Fig. 1 is a schematic diagram of a f irst example of an apparatus according to the present invention; and Fig. 2 is a schematic diagram of a second example of an apparatus according to the present invention.

Referring to Figure 1, a chemical sterilising apparatus according to a first embodiment of the invention is shown.

The chemical sterilising apparatus 1 has a first reagent supply device 2 and a second reagent supply device 3. The number of reagent supply devices can be varied depending upon the number of reagents required by the specific chemical sterilisation method employed by the apparatus.

Each of the reagent supply devices 2,3 comprises a respective reagent storage vessel 2A,3A, connected to first and second controlled pumps 2B, 3B. The reagents pumped by the pumps 2B,3B are carried by pipework to a mixing nozzle 18 which mixes the two reagents. The mixed reagents from the mixing nozzle 18 are carried by further pipework into a bottom tank 4.

The bottom tank 4 is also supplied with water from the mains water supply through a mains water filter 5. The supply of water from the water main through the filter 5 into the bottom tank 4 is controlled by a first valve 6. The mains filter 5 is a 5 micrometre filter. That is, the mains filter 5 contains a filter layer including a very large number of pores having an average pore size of 5 micrometers or less.

The bottom tank 4 provides an air break between the mains water supply and the apparatus and so ensures that it is impossible for fluid to pass from the apparatus to contaminate the mains water supply.

The mixture of filtered water and the two reagents in the bottom tank- 4 can be pumped by a third controllable pump 7 consecutively through successive first and second filters 8 and 9 to a sterilising chamber or soak tank 10 through an inlet nozzle arrangement 11.

i i 1 The first filter 8 is a 0.5 micrometer pre-filter. The first filter 8 contains a filter layer including a very large number of pores having an average pore size of less than 0.5 micrometers.

The filtered fluid output from the first filter 8 is further filtered by the second sterile filter 9. The second filter 9 is a 0.2 micrometer filter containing a filter element having a very large number of pores with an average pore size of less than 0.2 micrometers.

The inlet nozzle arrangement 11 comprises three separate nozzle parts, a misting or fogging nozzle part 11A which converts the fluid passing through it into a fine mist or fog of dispersed liquid droplets, a spray nozzle part 11B which allows fluid to pass through it in one or more essentially continuous streams and a flushing nozzle part 11C, to which tubular objects to be sterilised, for example endoscopes, can be connected to sterilise their internal surfaces. Access of fluid to the flushing nozzle part 11C is controlled by a second valve 19.

The sterilising chamber 10 is provided with an openable sealing lid 10A and any fluid within the sterilising chamber 10 can be drained away through a coarse filter 20 and a third valve 12 by a fourth drain pump 13. The coarse filter 20 prevents any dirt or loose objects carried by the fluid in the sterilising chamber 10 passing into the third valve 12 and fourth pump 13 and possibly damaging them.

The sterilising apparatus 1 further includes control means (not shown) which controls operation of all of the pumps 2B,3B, 7 and 13 and valves 6, 12 and 19 according to a prearranged sequence set by an operator.

In operation, the lid 10A of the sterilising chamber 10 is opened and objects to be sterilised are placed within the sterilising chamber 10. The support structures to hold objects to be sterilised may be fixedly or removably fitted within the sterilising chamber 10 if desired. Any tubular objects having shapes which cannot be reliably internally sterilised by immersion are connected to the flushing valve part 11C. The lid 10A of the sterilising-chamber 10 is then closed and sealed and the control system is instructed to begin the sterilising operation.

As a safety precaution, the control system operates a remote locking mechanism to lock the lid 10A of the sterilising chamber in place to prevent operator access to or opening of the sterilising chamber 10 during the sterilising operation.

The control system opens the first valve 6 and allows a predetermined amount of water to pass through the mains filter 5 into the bottom tank 4. Simultaneously, the control system operates the first and second pumps 2B and 3B to pump predetermined quantities of the two reagents through the mixing nozzle 18 and into the bottom tank 4.

The control system operates the mains valve 6 and first and second pumps 2B and 3B to generate a sterilisation solution having appropriate concentrations of the two reagents in water in the bottom tank 4. The total amount of sterilising solution formed in the bottom tank 4 can be fixed. However, it is preferred to allow the total amount of solution formed in the bottom tank 4 to be selected by the control system in response to a signal from the operator or generated by a sensor indicating the depth within the sterilising tank 10 occupied by the objects to be sterilised. The control system will then operate the mains valve 6 and first and second pumps 2A and 2B to generate a sufficient volume of the sterilising solution in the bottom tank 4 to fill the sterilising tank 10 to a' sufficient depth to completely cover the objects to be sterilised.

It has been found that when pumping of the reagents into the bottom tank 4 is begun at the same time as mains water is allowed into the bottom tank 4 and provided the pumping of the reagents into the bottom tank 4 is completed before the supply of mains water to the bottom tank 4 is stopped, it can easily be arranged by appropriate positioning of the pipes depositing the reagents and water into the bottom tank 4 that the turbulence is generated fully and evenly mixes the reagents throughout the solution in the bottom tank 4. However, if the above criteria were not met or if the inlet points of the reagents and mains water cannot be appropriately positioned, a mechanical or electromechanical stirring system can be used in the tank 4 to ensure full and even mixing.

once the sterilising solution has been mixed in the bottom tank 4, the con trol system sets the second valve 19 to a f irst position in which it directs a part of the f luid- from the second filter 9 to the flushing nozzle part 11C and operates the third pump 7 to pump the sterilising solution through the first and second filters 8 and 9 and nozzle arrangement 11 into the sterilising tank 10.

Part of the sterilising solution passes through the misting nozzle part 11A and is admitted into the chamber 10 as a fog of droplets which are deposited over the entire internal surface of the sterilising chamber 10 including the inner surface of the lid 10A. Another part of the sterilising solution passes through the second valve 19 to the flushing nozzle part 11C and passes through any tubular objects to be sterilised connected to the flushing nozzle part 11C and into the sterilising chamber 10. The remainder of the sterilising solution enters the sterilising chamber 10 through the nozzle part 11B. The control system operates the third pump 7 until all of the sterilising solution has been pumped out of the bottom tank 4. As a result all of the objects to be sterilised in the sterilising chamber 10 are immersed in the sterilising solution, the interiors of any tubular objects connected to the flushing nozzle part 11C are flushed with the sterilising solution and all internal parts of the sterilising chamber 10 and any fittings or support structures situated within the sterilising chamber 10 are drenched with sterilising solution by the deposition of droplets emitted from the misting nozzle part 11A.

The nozzle arrangement 11 employs three separate nozzle parts 11A, 11B and 11C because the resistance to fluid flow of the misting nozzle part 11A and tubular objects connected to the flushing nozzle part 11C will normally be large. If a misting nozzle part and a flushing nozzle part only were used, either the third pump 7 would have to pump the sterilising solution up to a very high pressure or filling the sterilising chamber 10 with the sterilising solution would take an unacceptably long time.

The control system then allows the objects to be sterilised to remain immersed in the sterilising solution for a preset sterilising time. This preset time is of course dependent upon the reagents used in the sterilising solution and the concentrations thereof. Once this soaking time has elapsed, the control system opens the third valve 12 and operates the fourth pump 13 to empty the sterilising solution from the sterilising tank 10 through the coarse filter 20 into a drain. When the sterilising tank 10 is empty of sterilising solution, the control system closes the third valve 12 and stops the fourth pump 13.

At some time after stopping the third pump 7, the control system opens the first valve 6 to allow a predetermined amount of mains water to pass through the mains filter 5 into the bottom tank 4. The control system then closes the first valve 6. Where the amount of sterilising solution generated in the bottom tank 4 can be varied, the amount of mains water allowed into the bottom tank 4 at this stage may also be varied. However, for reasons of simplicity, it is preferred that a fixed amount of water be allowed into the bottom tank 4 at this time.

After the third valve 12 has been closed and fourth pump 13 has been stopped, the control system operates the third pump 7 to pump rinse water from the bottom tank 4 through the first and second filters 8 and 9 and nozzle arrangement 11 into the sterilising tank 10. The second, sterile filter 9 has a sufficiently small pore size that any micro-organisms such as bacteria contained in the mains water are unable to pass through the second, sterile filter. Accordingly, since the second filter 9, the nozzle arrangement 11 and the pipework connecting the second filter 9 to the nozzle arrangement 11 have all been sterilised by the sterilising solution, the water pumped into the sterilising chamber 10 through the nozzle arrangement 11 is sterile, preventing recontamination of the objects to be sterilised during the rinsing process.

The rinsing water is pumped through the nozzle arrangement 11 into the sterilising chamber 10 to rinse the objects sterilised by the sterilising solution. A mist of water droplets produced by the misting nozzle part 11A ensures that all the internal surfaces of the sterilising chamber 10 which have been sterilised by the mist of sterilising solution droplets are rinsed, while water from the flushing nozzle part 11C ensures that the interior of any tubular objects connected to the flushing nozzle part IIC is rinsed.

When all of the water has been pumped out of bottom tank 4, the control system switches off the third pump 7. Then, after waiting fora rinsing period to ensure that the contents of the sterilising chamber 10 have been thoroughly rinsed, the control systems opens the third valve 12 and operates the fourth pump 13 to pump all of the rinse water out of the sterilising chamber 10 through the coarse filter 20 to drain and simultaneously sets the second valve 19 to a second position in which a flow of sterile air is supplied to the flushing nozzle part 11C to blow the rinsing water out of any tubular objects connected to the flushing nozzle part 11C. When all of the rinse water has been pumped out of the sterilising chamber 10, the control system closes the third valve 12, sets the second valve 19 back to its first position, and stops the fourth pump 13.

The control system then repeats the rinsing phase. During the second rinsing phase the supply of sterile air through the flushing nozzle part 11C is continued for a sufficient period to dry the interiors of the connected tubular objects.

The control system then operates the remote locking device to unlock the lid 10A of the sterilising chamber 10 and indicates to the operator that the sterilising process has been completed. Both the objects to be sterilised within the sterilising chamber 10 and all internal surfaces of the sterilising chamber 10 have been sterilised and rinsed. Accordingly, the sterilised objects will remain sterile until such time as the sterilising chamber 10 is opened to remove the objects. Further, since all internal surfaces of the sterilising chamber 10 are rinsed, there is no risk of an operator coming into contact with residual sterilising solution when removing the sterilised objects from the sterilising chamber 10.

1 A second sterilising system 101 embodying the invention is shown in Fig. 2.

Similarly to the first embodiment, objects to be sterilised are placed in a sterilising chamber 10 and a lid 10A of the sterilising chamber 10 is closed. The operator then instructs the control system (not shown) to begin the sterilising operation.

First, the controller operates a remote locking device (not shown) to ensure that the lid 10A of the sterilising chamber 10 cannot be opened during the sterilising operation. Then, the control means opens a first valve 6 to allow a predetermined amount of water into a bottom tank 4 through a mains filter 5 and operates first and second pumps 2B and 3B to pump predetermined quantities of two reagents-through a mixer nozzle 18 into the bottom tank 4, as in the first embodiment.

Also, the control system sets first to third directional -g- valves 14 to 16 to respective first positions, in which the first directional valve 14 allows water from the bottom tank 4 to be supplied to a third pump 7, the second directional valve 15 directs fluid from the third pump 7 along a pipe branch 18 to the third directional valve 16 and the third directional valve 16 directs fluid from the second directional valve 15 to a nozzle arrangement 11. Then, the control system starts the third pump 7 to pump the sterilising solution from the bottom tank 4 through the first to third directional valves 14 to 16 and nozzle arrangement 11 into the sterilising chamber 10. Similarly to the first embodiment, the misting nozzle part 11A ensures that all internal surfaces of the sterilising chamber 10 are drenched with the sterilising solution and the flushing nozzle part 11C ensures that the interiors of any tubular objects connected to the flushing nozzle part 11C are flushed with the sterilising solution.

Once the sterilising solution from the bottom tank 4 has been pumped into the sterilising chamber 10, the control unit stops the third pump 7, opens a third shut-off valve 12 and moves first to fourth directional valves 14 to 17 into respective second positions, in which the first directional valve 14 directs fluid from the fourth directional valve 17 to the third pump 7, the second directional valve 15 directs fluid from the third pump 7 through a first pre-filter 8 and a second sterile filter 9 to the third directional valve 16, the third directional valve 16 directs fluid filtered by the pre-filter 8 and sterile filter 9 to the nozzle arrangement 11 and the fourth directional valve 17 directs fluid from the sterilising chamber 10 which has passed through the coarse filter 20 and the third shut-off valve 12 to the first directional valve 14. Then, the control unit re-starts the third pump 7.

Thus, the sterilising solution from the sterilising chamber 10 is pumped by the third pump 7 through the first pre-filter 8 and second sterile filter 9 and back through the nozzle arrangement 11 into the sterilising chamber 10. This pumping is continued for sufficient time to ensure that all of the pumped circuit between exit from and re-entry to the sterilising chamber 10 is flushed with sterilising solution from the sterilising chamber 10 before the control unit stops the third pump 7.

The control unit then waits for a preset sterilising time to ensure that the objects in contact with the sterilising solution are thoroughly sterilised and then starts a fourth pump 13 and sets the fourth directional valve 17 to a first position in which it directs fluid from the sterilising chamber 10 which has passed through the coarse filter 20 and the third shut off valve 12 to the fourth pump 13 and so to the drain. If desired, the control unit can close the third shut-off valve 12 during the sterilising period. If this is done, the control unit will need to re-open the third shut-off valve 12 on or before starting the fourth pump 13.

Pumping continues until all the sterilising solution has been drained from the sterilising chamber 10 and the control unit then stops the fourth pump 13 and closes the third shut-off valve 12.

Then, the control unit 4 open the first shut-off valve 6 to allow mains water to flow into the bottom tank 4. once sufficient water has been passed into the bottom tank 4, the control unit closes the first shut-off valve 6. Similarly to the first embodiment, it is convenient for the amount of rinse water passed into the bottom tank 4 in the rinse phase to be fixed and greater than or equal to the amount of sterilising solution produced in the bottom tank 4 earlier in the cycle. Although this filling of the bottom tank 4 with mains water is referred to as taking place after the sterilising solution has been drained from the sterilising chamber 10, this can be carried out at any convenient time after pumping of the sterilising solution out of the bottom tank 4 has been stopped.

Next, the control unit sets the first directional valve 14 back to its first position and starts the third pump 7 to pump the rinse water in the bottom tank 4 through the first pre-filter 8 and second sterile filter 9 to the nozzle arrangement 11 and into the sterilising chamber 10. When all of the rinse water has been pumped from the bottom tank 4 into the sterilising chamber 10, the control unit stops the third pump 7.

Similarly to the first embodiment, the mist of water droplets produced by the misting nozzle part 11A ensures that all the internal surfaces of the sterilising chamber 10 which have been sterilised by the mist of sterilising solution droplets are rinsed, while the water passing through the flushing nozzle part 11C ensures that the interiors of any connected tubular objects are rinsed out.

The pores of the second sterile filter 9 are so small that microorganisms such as bacteria in the mains water cannot pass through the sterile filter 9. Accordingly, since the sterile filter 9 and all pipework between the sterile filter 9 and the nozzle arrangement 11 have been exposed to the sterilising solution, the rinse water passed to the sterilising chamber 10 from the sterile filter 9 will be sterile.

The rinse water is then allowed to remain in the sterilising chamber for a predetermined rinsing period.

At the end of the rinsing period, the control unit opens the second shutoff valve 12 and starts the fourth pump 13 to pump the rinse water away to the drain. Simultaneously, the control unit sets the second valve 19 to a second position to direct a flow of sterile air through the flushing nozzle part 11C to blow the rinsing matter out of any connected tubular objects. When all of the rinse water has been pumped from the sterilising chamber 10, the control unit stops the fourth pump 13, closes the second shut-off valve 12 and sets the second valve 19 back to its first position.

The control system then repeats the rinsing phase. During the second rinsing phase the supply of sterile air is continued for a sufficient period to dry the interiors of any connected tubular objects, similarly to the first embodiment.

Finally, the control system releases the remote locking mechanism so that the operator can open the lid 10A of the sterilising chamber 10 and take out the sterilised objects when required.

The objects to be sterilised and the entire internal surface of the sterilising chamber 10 have been sterilised and rinsed during the sterilising operation and accordingly the sterilised objects will remain sterile without any risk of contamination until the lid 10A of the sterilising chamber 10 is opened by the operator.

In the described embodiment, the second and third directional valves 15 and 16 are moved simultaneously between their first and second positions and vice versa by the control unit. Accordingly, it is convenient'for the second and third directional valves 15 and 16 to be interlinked and operated by a single actuator.

In the description, the first and fourth directional valves

14 and 17 are described as being moved between their respective first and second positions at different times. However, it will be understood from the description that it would be possible to move the first and fourth directional valves 14 and 17 between their respective first and second positions and vice versa simultaneously although this would result in some superfluous valve movements of valves which were not controlling a fluid flow at the time. Accordingly, for simplicity of the control system and to minimize complexity, it is convenient for the first and fourth directional valves 14. and 17 to be interlinked and operated by a single actuator.

In the second embodiment, the use of the third directional valve 16 and a nozzle arrangement including a misting nozzle part 11A, a nozzle part 11B and a flushing nozzle part 11C is not essential. An alternative would be to connect the outlet of the sterile filter 9 to a misting nozzle and a flushing nozzle and connect the pipe branch 18 to a non-misting nozzle. The generation of a mist of sterilising solution droplets to cover all internal surfaces of the sterilising chamber and the passing of sterilising solution through any connected tubular objects would then only be carried out during pumped circulation of the sterilising solution through the pre-filter and sterile-filter. In this case, it would be necessary to add a further operating step during each rinse phase of pumping the rinse water from the sterilising chamber through the misting nozzle and the flushing nozzle to rinse all internal surfaces of the sterilising chamber and the interior of any connected tubular objects.

In both embodiments, if no tubular objects to be sterilised are connected to the flushing nozzle part 11C, it is preferred that sterilising solution and rinsing water is still passed through the flushing nozzle part 11C to ensure that all pipework connected to the sterilising chamber 10 is sterilised and rinsed. However, it is preferred that the blowing of sterile air through the flushing nozzle part 11C not be carried out if operator input or a sensor signal indicates that no tubular objects are connected to the flushing nozzle part 11C.

The flushing nozzle part 11C is useable to ensure sterilisation and rinsing of a range of tubular objects, and particularly the fine lumens of endoscopes.

i In both of the embodiments of the invention, a f urther initial cleaning phase could be added in which the objects to be sterilised within the sterilising chamber are first cleaned either by water only or by a cleaning solution produced in the bottom tank 4 by mixing mains water and a cleaning agent and pumping the cleaning solution into and later out of the sterilising chamber 10.

In both embodiments of the invention the use of two rinse phases is described. This is preferred, but not essential. The number of rinse phases used can be varied as necessary in view of the sterilising solut ' ion composition and concentration used.

In the embodiments, the use of separate directional valves, shut-off valves and pumps or combined units including two or more of these functional elements can be employed as convenient.

The use of a mains filter is preferred, but not essential.

Although the use of a sterile filter is essential, whether or not a prefilter is used in conjunction with the sterile filter will depend upon the precise parameters of the apparatus, the quality of the mains water andtype of sterile filter used and may also depend on whether a mains filter is employed.

It is preferred that all surfaces exposed to the sterilising solution or the constituent reagents of the sterilising solution be formed of stainless steel, medical plastic or some other chemically inert material.

Suitable reagents for use to produce the sterilising solution are sodium chlorite in a water base and an organic acid blend with corrosion inhibitors, or peracetic acid and a stabilising and buffering system including corrosion inhibitors, or glutaraldehyde and an activator, or peroxygen compound/ hydrogen peroxide and de-ionised water with corrosion inhibitor. However, this list is not exhaustive.

Both of the embodiments can be employed with sterilising solutions formed from one or a plurality of reagents. The number of reagent reservoirs and associated pumps can of course be varied as necessitated by the number of reagents. Where plural reagents are used, it is convenient to arrange the pump rates of the associated pumps such that the pumps will need to pump for the same period of timi to produce the sterilising solution. This simplifies control and allows the pumps to be driven by a single motor.

i J; In general, reagents f or use in sterilising solutions are chemically aggressive substances so the use of peristaltic pumps is preferred.

It is preferred that the bottom tank have a smaller liquid volume than the sterilising chamber.

In both embodiments, the volume of sterilising solution introduced into the sterilising chamber may be fixed, selected by the operator or automatically selected based upon sensing of the sterilising chamber contents. Similarly, the volume of rinse water introduced to the sterilising chamber may be arranged to be equal to the volume of sterilising solution or greater than the volume of sterilising solution by a preset amount and in systems where the volume of sterilising solution is variable may be fixed or variable in dependence upon the volume of sterilising solution.

Fluid volumes and timings will have to be determined in any system based upon the volume, shape and potential contents of the sterilising chamber and the sterilising solution used.

In the above description the term sterilising includes disinfecting and sanitising.

The supply of sterile air through the flushing nozzle part 11C is useful to dry the inside of any connected objects, but is not essential.

The above description is of examples only and it will be clear to the person skilled in the art that the invention can be applied to alternative arrangements.

QAIMS 1. A chemical sterilising apparatus comprising:

a sterilising chamber in which objects to be sterilised are placed; tank; first supply means for supplying a predetermined amount of a first reagent to the tank; means for supplying a predetermined quantity of water to the tank through an air break to combine the reagent with water to form a sterilising solution; and means to supply the sterilising solution to the sterilising chamber.

Claims (1)

1. 2. Apparatus as claimed in Claim 1, and further comprising a filter able

   to block the passage of micro-organisms, through which the sterilising solution is supplied to the sterilising chamber and means to supply rinsing water to the sterilising chamber through the filter.

   3. Apparatus as claimed in Claim 2, in which the means to supply the sterilising solution to the sterilising chamber also supplies the rinsing water to the sterilising chamber.

   4. Apparatus as claimed in claim 2 or Claim 3, and further comprising a misting nozzle through which at least a part of the sterilising solution can be supplied to the sterilising chamber such that all internal surfaces of the sterilising chamber are contacted by the sterilising solution.

   5. Apparatus as claimed in Claim 4, in which at least a part of the rinsing water can be supplied to the sterilising chamber through the misting nozzle such that all internal surfaces of the sterilising chamber are rinsed.

   6. A chemical sterilising apparatus comprising:

   a sterilising chamber in which objects to be sterilised can be placed; a first supply means for supplying a predetermined amount of a first reagent; means f or combining the reagent with a predetermined quantity of water to form a sterilising solution and supply it directly to the sterilising chamber; means to circulate sterilising solution from the sterilising chamber through a f ilter able to block the passage of microorganisms; and means to supply rinsing water to the sterilising chamber through the filter. _ Apparatus as claimed in Claim 6, and further comprising means to circulate sterilising solution from the sterilising chamber for resupply to the sterilising chamber through a misting nozzle such that all internal surfaces of the sterilising chamber are contacted by the sterilising solution.

   8. Apparatus as claimed in Claim 7, and further comprising means to circulate rinsing water f rom. the sterilising chamber through the misting nozzle such that all internal surfaces of the sterilising chamber are rinsed.

   4 9. Apparatus as claimed in Claim 8, in which the means to circulate sterilising solution is also the means to circulate rinsing water.

   10. Apparatus as claimed in any one of Claims 2 to 9, in which the filter comprises a filter having apertures with an average size of less than 0. 2gm.

   11. Apparatus as claimed in any preceding claim, and further comprising a second supply means for supplying a predetermined amount of a second reagent for combining with water and the first reagent to form the sterilising solution.

   12. Apparatus as claimed in any preceding claim, and further comprising a flushing nozzle through which at least a part of the sterilising solution can be supplied to the interior of objects to be sterilised in fluid communication with the flushing nozzle.

   13. Apparatus as claimed in claim 12, when dependent on any one of Claims 2 to 11, in which at least a part of the rinsing water can be supplied to the interior of objects to be sterilised in fluid communication with the flushing nozzle to rinse them.

   14. A chemical sterilising apparatus comprising: a sterilising chamber in which objects to be sterilised are placed; a misting nozzlej and means to supply a sterilising solution to the sterilising chamber through the misting nozzle such that all internal surfaces of the sterilising chamber are contacted by the sterilising solution.

   15. Apparatus as claimed in Claim 14, and further comprising means to supply rinsing water to the sterilising chamber through the misting nozzle such that all internal surfaces of the sterilising chamber are rinsed.

   16. Apparatus as claimed in Claim 15, in which the means to supply the sterilising solution also supplies the rinsing water.

   17. A chemical sterilising apparatus substantially as shown in, or as described with reference to, Figure 1 of the accompanying drawings.

   18. A chemical sterilising apparatus substantially as shown in, or as described with reference to, Figure 2 of the accompanying drawings.