The Principles of Medical Device Decontamination

Sterilization Process

Sterilization Standard

Sterilizer Standard

Any Sterilization Process (Non- specific generic standard)

BS EN ISO 14937 1

BS ISO TS 22421 2

BS EN 13060 4 (small) BS EN 285 5 (large)

Moist Heat (Steam)

BS EN ISO 17665 3

Dry Heat

BS EN ISO 20857 6

None

Irradiation

BS EN ISO 11137 7

None

Vaporised Hydrogen Peroxide BS EN ISO 22441 8

BS EN 17180 9 *

Ethylene Oxide Gas

BS EN ISO 11135 10

BS EN 1422 11 **

Low Temperature Steam with Formaldehyde

BS EN ISO 25424 12

BS EN 14180 13

Table 10.1

The British Standards for Sterilization processes and sterilizers *In preparation **Undergoing revision

The process variables for moist heat sterilization are time and temperature in the presence of moisture. Pressure is a cycle variable and allows a carefully controlled process to be delivered.

A typical saturated steam sterilization process consists of three basic phases. In phase one, air remaining in the chamber once the door is closed, is removed by a series of evacuation and steam injection pulses. The application of such pulses gradually replaces the air within the chamber and most importantly the load, by steam. At the end of the air removal stage steam is injected into the chamber to a predefined pressure, giving an equivalent temperature and at this point the next phase commences, the sterilization stage. During the sterilization stage any microorganisms present on or in the load will be rapidly inactivated. After a suitable exposure period

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