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laboratory. Here the temperature probes and test equipment carried by the engineers are regularly tested and verified for accuracy. This ensures the accuracy of the thermocouples in the above procedure.

Whether part of a planned maintenance programme, routine service or an emergency call-out, any irregularities identified by the engineer during service require him to make adjustments to ensure that a fully operational condition is maintained.


POOR STERILISATION Temperature recorders, printers and built-in loggers are available for most autoclaves, but these only give an indication that the autoclave itself has run correctly for the duration of the sterilising cycle. They are useful as a routine check to pick up cycle irregularities but they will not necessarily detect anomalies within the load itself during a normal cycle.

On a day to day basis, the effectiveness of sterilisation of any one particular run can be checked with the use of indicators placed within the load. These include

autoclave tapes and indicator strips that change colour with temperature, more sophisticated strips that only change colour when they experience the correct temperature and pressure for sterilisation and biological indicators that contain viable bacterial spores (the most difficult things to sterilise), which can be incubated after sterilisation to check for viability.

Another useful procedure is that of load Performance Qualification Testing which can be carried out by the service engineer during commissioning of the autoclave. It is usually achieved using a calibrated, multi-channel, data logger so that considerable numbers of points in the load, together with salient points on the autoclave, can be logged throughout a hold time [Fig 3]. Once qualification of the empty chamber has been accepted, load testing should be performed. Probes are placed inside typical loads and the heat transfer time is determined to measure the temperature profile during sterilization cycle.

Simultaneous monitoring of the chamber pressure is also useful in checking the efficiency of the air removal/ replacement system. Analysis of these results may point to problems in the setup of the autoclave or in the way the load is contained. Significant differences can be seen, for instance,

FIG 2 Tomorrow’s Laboratories | 21


between glass and plastic bottles or plastic and metal discard containers, or between single and double bagged discard loads.

THE SERVICE CONTRACT Most leading autoclave manufactures offer first class warranties which can be extended with provision of a Preventative Maintenance Plan. These are designed to keep your autoclave in safe, efficient working order and to reduce the possibility of costly downtime.

Maintenance plans tend to run on a yearly basis and generally incorporate a number of scheduled service visits by a fully trained autoclave Service Engineer working from a well-equipped vehicle. The engineer will carry out a thorough service covering all aspects of the autoclave in accordance with a checklist, making adjustments where necessary.

At the end of a visit, a completed Maintenance Report and Service Checklist should be presented to the customer for approval, with copies retained; they will prove invaluable if you need to comply with stringent Quality Assurance or Insurance regulations.

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