Autoclave care and maintenance advice

Autoclave care and maintenance advice

The following extract is taken from an Astell Service bulletin. It contains best practice for cleaning and maintaining an autoclave to ensure ongoing performance and reliability.


Although the historical safety record of laboratory sterilizers is good, remember at all times that they store considerable potential energy and should be treated with respect and care. If correctly used and cared for, your Astell autoclave will provide long, reliable and safe service.

Pay attention to regular maintenance. Never force the locking mechanism, or operate the machine with any leaks, or incorrectly operating parts.

Report any defects to your Engineering staff / Supervisor. If deterioration or defects are noticed, record them in a logbook and contact our Service Department. Record the results of annual and periodic inspections. Every 4 – 6 weeks is recommended for periodic checks. Check the logbook before you start using the machine, as someone else may have recorded a fault of which you are not aware.


Autoclave cycle selection
Check that the cycle selected has the correct settings for your requirement.

Use of the Load Probe
It is imperative that the Load Probe (if fitted) is consistently used and located in a similar position within the chamber for each cycle, using a sample Duran bottle filled with water.

Load containers and loading
Poor loading technique frequently results in failure to sterilize the complete load because any air entrapped will afford protection to micro-organisms.

It should be remembered that adequate space should be left between the articles being sterilized to allow all air to be flushed out by the steam. Empty vessels, narrow necked flasks and bottles should be placed upside down to prevent condensate collecting and to allow air to drain from them.

Perforated metal or plastic containers for use within an autoclave, or metal baskets, are suitable and any supports or dividers used must be perforated. Unless containers designed to hold spilt load material are used, the chamber will require very frequent cleaning to avoid contamination of the Drain Reservoir water by the leaking load liquids.



Monitor cycles
Monitor cycles to ensure that all indicators and information displayed on the screen are as expected.  Any errors will be highlighted on the screen and the autoclave control system will automatically take the required action (i.e. halt the cycle in the event of a critical error to the sterilization process).

Inspect door gasket for damage and cleanliness
With the autoclave switched OFF and the door OPEN, visually inspect the gasket and its mating surfaces for signs of debris, damage and corrosion. Clean by wiping with a damp cloth.

Check the autoclave temperature probes for signs of damage
With the autoclave switched OFF and the door OPEN, visually inspect the probe at the rear of the inside of the vessel for signs of debris or damage.

Door operation
Close the door to check all functions are correct in conjunction with the operating manual.

Water condition
Check the condition of water in the water tank or trough.  Agar, blood, faeces or solid rubbish could cause problems and failures. Spillage of any of the above in any autoclave will cause blockage of pipework, valves and drains etc. and must be avoided at all costs.


In addition to the stated Daily Routine checks:

Check water level probe (if present)
For electrically heated autoclaves (Heaters in Chamber), ensure that the water level probe is regularly inspected and cleaned if necessary to avoid the build-up of deposits.

Chamber cleaning
The chamber should be cleaned internally sufficiently often to prevent build-up of contaminants within the water or on the water level probe, and we would suggest that for a machine in daily use the chamber should be checked once a week and cleaned if necessary in accordance with the operating manual.
Spillage of any substance in an autoclave will cause blockage of pipework, valves and drains etc. and must be avoided at all costs.

Temperature / Pressure monitoring
During a cycle, check correlation of gauge pressure against displayed pressure.
This is done by assessing the stated control temperature and vessel pressure during the sterilization stage ONLY, against a Steam Table Graph (supplied).
Any noticeable deviation from this reading should be recorded and referred to Astell Scientific for comments.

Autoclave safety features
The autoclave / sterilizer is fitted with safety interlocks to prevent the opening of the lid or door when the chamber is pressurized and to prevent pressurization if the door / lid is not fully closed. The UK Health & Safety Regulations stipulate that a competent person shall inspect the closure system and interlocks at regular intervals. All operators should be trained in the use of the controls, operating procedures and the function of safety devices.

Unlock and open the door
Check for smooth swinging and / or lifting action without grating or crunching noises or, looseness.

U.K. HSE Guidance Note PM73 requires that such checks be carried out regularly.
To comply with HSE requirements, instructions regarding testing of these interlocks must be permanently displayed close to the sterilizer operating location.

Safety valve test
Check that the safety valve is okay by completing the safety valve test as prompted by the machine software.


The safety valve is to be found inside the case close to the label denoting ‘SAFETY VALVE’ at the side on the same as the hinge, accessed through a covered cutout.

Check printer paper (if fitted)
If the autoclave has the data printer option fitted check the paper roll and replace if necessary.

Blow down the Steam Generator (if fitted)
Blow down is necessary to avoid a concentration of impurities, a by-product of the continuing production of steam.

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