Vertical Autoclave Operation, cleaning and calibration

1.0 OBJECTIVE

To describe a procedure for Operation, Cleaning and Calibration of Double Door Autoclave Make: Osworld.

2.0 SCOPE

This procedure is applicable to Operation, Cleaning and Calibration of Double Door Autoclave in Microbiology Lab.

3.0 RESPONSIBILITY

3.1 Microbiologist /Officer is responsible for the execution. 

3.2 HOD or designee is responsible for review, effective implementation and compliance to the Operation, cleaning and calibration of Vertical Autoclave for execution. 

4.0 PROCEDURE 

4.1 Operation

4.1.1 Open the autoclave lid by pressing foot lifting lock and unlock and fill the water upto the stand level before starting the autoclave.

4.1.2 Load the items to be discard in the autoclave and shut the lid, make sure that knobs on lid are evenly screwed down manually tighted opposite ends by hand.

4.1.3 Switch on the mains to supply the power followed by the toggle switch located in the control panel to activate the heat generator.

4.1.4 The digital temperature controller led will glow and indicates the present actual temperature in the autoclave i.e. ambient temperature and press the start button.

4.1.5 Heating starts, temperature indicator gradually show a rise in temperature nozzle with nose pipe which let out hot air and steam.

4.1.6 Once air in entire chamber is evacuated, the solenoid valve is shut.

4.1.7 When the pressure gauge reaches upto 15-17 psi and the temperature reaches to 121°C. 

4.1.8 When it stabilizes at this temperature and pressure, the timer for sterilization automatically begins. 

4.1.9 After the stipulated sterilization time temperature controller automatically stops heater and automatic steam evacuation through nozzle and exhausting the autoclave steam completely.

4.1.10  Once the temperature in the sterilizer drops to 60°C or the pressure drops to 0 psi, the autoclave lid can be open and material can be removed. Switch off the system; unload the items by opening the autoclave door.

4.1.11 A safety valve spring loaded type is provided, in case excess pressure builds up it is released through the safety valves.

4.1.12 Enter the details like Particulars of the loaded material and sterilization time in the vertical autoclave logbook as per the attachment # 1 format No.: QEO016/F01.

4.1.13 Indicate the load no as A-XXX, where ‘A’- Autoclave no. and ‘XXX’ - serial number in sequence.Ex; 1-001 for vertical autoclave load/cycle number one.

6.2 CLEANING

6.2.1 Clean the autoclave after each cycle with DM/Purified water.

6.2.2 The inner chamber shall be cleaned with 2.5% savlon or 2.5% dettol every day at the end of each cycle.

6.2.3 Keep the autoclave in closed condition while not in use.

6.2.4 Clean the drain line by pouring hot solution of tri sodium phosphate (3.0% in water) through the drain hole in the chamber for cleaning of grease, sticky substances to avoid clogging. This should be done for every fifteen days.

6.2.5 Prepare the cleaning solutions as per current version of SOP (Disinfectant Preparation).

6.2.6 Enter the details of cleaning in to the autoclave cleaning record as per attachment #2 

6.3 CALIBRATION

Validation by thermal probes

The validation of autoclave is carried out by following methods, Heat Distribution studies, Heat Penetration studies and by using biological indicator strips/ampoules of Bacillus stearothermophilus.

6.3.1 Heat Distribution test.

6.3.1.1 Place calibrated thermal probes in different locations within the autoclave as per the attachment # 3 

6.3.1.2 Place the probes in such a manner that the tip does not have any contact with the body of sterilizer.

6.3.1.3 Run the autoclave as per the point no 6.1

6.3.1.4 Record the temperature at the intervals of each minute all through the cycle.

6.3.1.5 Place the biological indicator at or near to the probes placed. 

6.3.1.6 Place the Bowie Dick test pack at the center of the chamber.

6.3.2 Heat  Penetration  test

6.3.2.1 Place the probes in such a manner that the tip does not have any contact with the body of sterilizer.

6.3.2.2 Run the autoclave as per the point no 6.1

6.3.2.3 Record the temperature at the intervals of each minute all through the cycle.

6.3.2.4 Run the cycles for minimum and maximum loads.

6.3.2.5 Place the biological indicator at or near to the probes placed.  

6.3.3 Method of analysis for biological indicator

6.3.3.1 Place the ampoule / strip of Bacillus stearothermophilus spores in a empty test tube and numbered it.

6.3.3.2 Take the tubes to respective area and place them in autoclave at or near to the probes placed.

6.3.3.3 After completion of sterilization cycle remove the tubes from the autoclave and carry out the analysis.

6.3.3.4 In case of strip, aseptically transfer the Bacillus stearothermophilus strip from each tube into separate tube of sterile Soyabean casein digest medium.  Mark the tubes appropriately.

6.3.3.5 Aseptically transfer a non-autoclaved Bacillus stearothermophilus strip into a tube sterile SCDM to serve as positive control.

6.3.3.6 Mark one tube of sterile Soyabean casein digest medium as negative control.

6.3.3.7 Incubate all the tubes at 55-60°C for seven days and observe them every day for any visual evidence of growth.

6.3.3.8 In case of ampoule for Bacillus stearothermophilus, incubate the ampoules as such at 55- 60°C for at least 48 hours.

6.3.3.9 Keep one un-autoclaved ampoule along with the tested ampoules to serve as positive control.

6.3.3.10 Record the results in Attachment # 4.

6.3.3.11 If there is no evidence of growth in any of the tubes except positive control or if the color of the ampoules remains purple or turns reddish brown, the results are valid.

6.3.3.12 If evidence of growth in any of the tubes except positive control tube or ampoule (color change to yellow) the results are invalid.  Repeat the test procedure using fresh Bacillus stearothermophilus strips / ampoules.

6.3.4 ACCEPTANCE  CRITERIA

6.3.4.1 The entire chamber area should show the set temperature uniformity and steam stability during Heat distribution and Heat penetration studies. Achieving a temperature of 121°C with saturated steam at the approx.1.2 Kg/cm2 (bar) pressure.

6.3.4.2 The coolest point within the chamber area should be determined in the heat distribution test.

6.3.4.3 The coolest point within a specified load and configuration should be determined during the heat penetration test.

6.3.4.4 All exposed Biological indicators should show negative result in the entire cycles.

6.3.4.5 A Range of + 3°C of the mean chamber temperature is acceptable.