The autoclave

Introduction

For a particular autoclave to be considered suitable for use as a system for treating biohazardous wastes it must be shown that one functioning cycle, under specified conditions of temperature, pressure and time, is sufficient to lower the concentration of a spore preparation (biological indicator) by 4 log at least.

The validation of an autoclave requires the following.
a) Defining the working parameters (temperature, time and pressure) for each of the established cycles (e.g. liquid, solid) before placing the autoclave into service. The (standard) operating conditions are determined from the following criteria.

• Typical loads, in terms of expected weight and maximum density, of the biological wastes to be treated are prepared.
• Before treatment, the biological indicators (e.g. Geobacillus stearothermophilus spores) are placed specifically in the areas that are least accessible to the steam.
• If no spore growth is detected in the operating parameters for treating a typical load, this validates the conditions of the cycle for that type of load.

b) Passing three consecutive tests before entering service.
c) Having a programme of preventive and corrective maintenance and a maintenance record.
d) Ensuring the autoclave has a system for continuously recording the temperature and pressure during the whole treatment cycle.
e) Certifying that the efficacy of the autoclave is tested with a biological indicator at least once every 40 hours of use or after repairs and recording this. A negative test result may indicate that the autoclave needs to be calibrated.
f) Keeping a use log.
g) Having a written procedure for using and maintaining the autoclave close at hand.

Any queries regarding the autoclave validation programme may be addressed to the IBC (e-mail: comite.bioseguretat@uab.cat, telephone: 8049).