When qualifying our autoclave what tests should we do? 

ISO 17665:2024 (Annex C) includes guidance on recommended periodic tests for moist heat sterilization processes.  This post will outline what tests are recommended, when they are suggested to be completed and at what ongoing periodic frequency they should be repeated.  Further posts will go into more detail on how these tests are performed and why.

The recommended schedule of tests has existed for many years, developing, and changing over time.  Published in the 1960’s, HTM 10 first outlined routine tests in Chapter IX, Routine Testing, recommending the Bowie and Dick Test (Daily), Leak Rate Test (at least weekly) and if fitted, sensitivity of the air detector in accordance with BS 3970-1:1966 (as amended in 1969) to require: - 

“… a device capable of detecting the presence of air in sufficient quantity to prevent the attainment of and maintenance of the sterilizing conditions within the load …. fitted as part of the automatic control.” 

HTM 10 was subsequently replaced with HTM 2010, that many of us will be familiar with and the schedule of validation and periodic tests within.  HTM 01-01 replaced HTM 2010 and is now the current guidance in UK healthcare. 

Broadly speaking testing falls into two parts. 

1. Firstly, the Schedule of Validation Tests outlined what tests should be conducted during Installation, [IQ] Operational [OQ] and Performance Qualification [PQ]. 
2. Secondly, the Schedule of Periodic Tests outlines ongoing routine tests and their frequency, nominally conducted daily, weekly, quarterly and annually, (Requalification [RQ]).

Following the test regime will ensure that you are in control of your sterilization process and indeed meet the requirements of Annex 1.  Read more here: Sterilization Control Strategy

Many of these tests and frequencies have been carried forward into ISO 17665:2024 and I would consider them to be Good Autoclave Practice.  The tables below outline the recommended tests from the standard: -

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Schedule of Validation Tests

Installation tests

• Safety tests and checks

 Operation Qualification (commissioning)

• Steam Quality Non-Condensable Gases   
• Steam Quality Dryness Value                  
• Steam Quality Superheat                        
• Steam Quality Contaminants                  
• Thermometric Test Small Load                 
• Thermometric Test Full Load                    
• Hollow Load Test                                     
• Bowie and Dick Test                                
• Air Leakage Flowrate Test                               
• Air Detector Small Load                         
• Air Detector Full Load                                
• Air Detector Function                                 
• Load Dryness Small Load Textiles                
• Load Dryness Full Load Textiles                   
• Load Dryness Metal Load                            
• Automatic Control Test                               

 Performance Qualification

• Bowie and Dick Test                                    
• Automatic Control Test   
• Thermometric Product Load Test
• Air Leakage Flowrate Test                     

Schedule of Periodic Testing

Daily

• Bowie and Dick Test                                     

Weekly

• Automatic Control Test                                  
• Bowie and Dick Test                                          
• Air Leakage Flowrate Test                                
• Air Detector Function                                    

Three monthly (Quarterly)

• Automatic Control Test                                   
• Bowie and Dick Test                                       
• Air Leakage Flowrate Test                              
• Air Detector Function                                     
• Thermometric Test Small Load                     

Annually

• Air Leakage Flowrate Test                                
• Automatic Control Test  
• Bowie and Dick Test  
• Thermometric Test Small Load                            
• Thermometric Test Full Load                             
• Air Detector Small Load                                    
• Air Detector Full Load                                     
• Air Detector Function                                       
• Thermometric Product Load Test 

• Steam Quality Non-Condensable Gases   
• Steam Quality Dryness Value                  
• Steam Quality Superheat                        
• Steam Quality Contaminants