Infection prevention and control guidelines

10. Reprocessing reusable medical devices

Loading the steriliser

      1. Loading the steriliser

Last revised: 17 Jun 2024

Loading the steriliser

Correct loading of the steriliser is important to ensure steam can reach and sterilise every surface of the load, to prevent sterile barrier systems from damage, and to facilitate drying (Table 10.8. Principles of steriliser loading).

A load must not exceed the practice’s validated parameters. This means a load cannot be larger or more difficult to sterilise than the ‘challenge load’ tested at time of annual validation/performance re-qualification. Any new load configurations that could possibly exceeding that of the validated ‘challenge load’ require re-validation (or the use of a Class 5 or 6 chemical indicator in emergency situations until validation is able to be performed as soon as possible).

It is preferable not to sterilise wrapped and unwrapped items in the same load. If this is necessary, do not place unwrapped items above the tray of wrapped items, because condensate may drip onto the wrapped packs below it.

Equipment used when loading the steriliser

Separators, trays and racks assist with correct loading.

Only validated, ARTG-listed sterilisation containers, load separators, perforated metal trays or cassettes may be used. The correct type depends on the steriliser model. These can be obtained through the steriliser manufacturer or medical supply company if not provided with the steriliser.

Load separators are used to space items (eg identical kidney dishes that would stack closely together, hindering air removal, steam penetration and drying).

Trays used in the steriliser must be perforated to allow steam penetration and condensation drainage during the sterilisation cycle. Use trays specifically designed and validate for the specific model of  steriliser. Multiple trays may be required if packs are sterilised flat as single layers.

Solid trays must not be used as they inhibit steam movement and steam can condense on them, leaving pools of moisture and possibly wetting packs.

Method of loading

Follow the loading instructions provided by the manufacturer.

General principles apply:

  • Follow the manufacturer’s instructions on placement of packs and use of equipment.
  • Ensure adequate space between each pack/pouch to facilitate air removal, allow steam penetration and facilitate drying – load trays loosely with a single layer of packs on each tray, within the boundaries of the loading tray.
  • Load the steriliser so that no items touch the walls. A square frame insert to achieve this may be supplied with the steriliser.
  • Loading of the steriliser follows the same pattern of loading described in the validation protocol.

Photographs or diagrams of the validated loading pattern and any lesser loading patterns used are useful as a reference.

Table 10.8. Principles of steriliser loading



Place only a single layer of packs on each tray and allow space between packs for air removal and steam penetration.

Place lighter items on top shelves and heavy items on lower shelves.

For items that are prone to entrap air and condensate, such as bowls, tilt on sides (eg 45° angle using a vertical rack) to allow air removal and steam penetration, and facilitate drainage and drying at the completion of the cycle.

Place single laminated pouches vertically in a spacer with paper to laminate, or horizontally, according to steriliser manufacturer’s instructions.

Load items within the boundaries of the shelf.

Do not place into the steriliser until the complete load is ready to be loaded.

Do not overload the chamber or allow packs to overlap.

Do not allow packages to touch the sides of the steriliser chamber.

Do not exceed the maximum weight or volume specified by the steriliser manufacturer

Do not exceed the challenge load.

Do not place instrument trays, hollow items or items that could collect moisture (eg bowls) above packs containing soft materials.