Autoclave (moist heat steriliser)

An autoclave kills microorganisms with moist heat: steam in direct contact with the load, or superheated water sprayed or cascaded over sealed containers that other cycles would damage (Annex 1, 8.55). Porous and hard-goods loads need air removed so steam can reach every surface; fluid loads in sealed containers heat from the outside in.

Annex 1 asks that "the whole of the load should reach the required temperature before measurement of the sterilising time-period starts" (8.52), that every cycle be recorded with safeguards to detect and fail a non-conforming cycle (8.50), and that worst-case load patterns be revalidated at least annually (8.39).

Where it sits: In the wash and preparation area for components, equipment and garments going to aseptic processing; at the end of the line for terminally sterilised product; in the microbiology laboratory for media and waste.

• —Equipment, tools and filling parts for aseptic processing
• —Stoppers and other components
• —Terminal sterilisation of filled product
• —Microbiology media and waste decontamination

In the reference facility: Equipment wash & parts preparation, Processing & formulation suite, Microbiology & environmental monitoring laboratory

Not covered on this page: Steam-in-place of fixed systems, covered with vessels and lines; Dry heat, radiation and gas sterilisation; Pure steam supply, covered on the clean steam page.

• 01Pressure chamber and doors. Holds the load; double-ended units pass sterile loads into the clean side.
• 02Steam supply, jacket and drain. Deliver steam and remove condensate; Annex 1 asks for temperature recorded at the chamber drain in prevacuum cycles (8.58).
• 03Vacuum pump. Removes air before and dries the load after sterilisation.
• 04Sterile air filter. Admits air to break vacuum without recontaminating the load.
• 05Control and independent recording probes. Control and record the cycle; Annex 1 gives duplex probes on independent systems as an example safeguard (8.50).
• 06Load carriers and protective packaging. Hold items so air can leave and steam can enter, and prevent recontamination (Annex 1, 8.56).

Connects to: Clean steam system; Cleanroom pressure cascade between the loading and unloading sides; Batch record and cycle record review; Biological indicator supply and microbiology laboratory.

• 01Temperature sensor (RTD or thermocouple). Drain and load temperature; positions set in validation and checked against an independent probe (Annex 1, 8.51). Watch for: sensor not at the location that matters (cold spot, load centre).
• 02Pressure transmitter (gauge or absolute). Chamber pressure, recorded for porous cycles and correlated with temperature (Annex 1, 8.57, 8.59). Watch for: gauge and absolute values compared directly.
• 03Air removal test (test pack or air detector). Air removal before sterilisation, normally daily or by an air detector (Annex 1, 8.61). Watch for: test run on a different cycle from production.
• 04Biological indicator. Lethality at worst-case locations during validation, as additional support (Annex 1, 8.42). Watch for: population, purity and identity of a new lot not verified (annex 1, 8.43).

• 01Temperature (limit, °C). Minimum and maximum during exposure, with tolerances defined and confirmed in validation (Annex 1, 8.59).
• 02Exposure (dwell) time (setpoint, min). Counted only once the whole load is at temperature (Annex 1, 8.52).
• 03Chamber or vessel pressure (measured, bar a or bar g or kPa). Recorded for porous cycles and correlated with temperature (Annex 1, 8.57, 8.59).
• 04Equilibration time (measured, s). Calculated in porous cycle validation (Annex 1, 8.59).
• 05F0 (equivalent sterilising time) (derived, min). For fluid cycles, with temperature and time (Annex 1, 8.59).
• 06Chamber vacuum leak rate (limit, mbar/min or kPa/min). Tested periodically, normally weekly, where the cycle has a vacuum phase, against the site’s defined criterion (Annex 1, 8.60).

SPEQ publishes no universal alarm or acceptance values: they depend on the process, the product and the site’s own qualification.

• 01Interlock: Door interlocks. Prevent the unloading door opening before a complete cycle, and both doors opening at once.
• 02Safety function: Pressure vessel protection. Relief valves and door locks under pressure protect people; their basis is pressure safety, not product quality.
• 03Alarm: Cycle fault and abort. Detects a cycle outside validated parameters and fails it (Annex 1, 8.41, 8.50).
• 04Procedure: Daily air removal and weekly leak tests. Normally daily and weekly respectively (Annex 1, 8.60, 8.61).
• 05Procedure: Cycle record review. Each cycle has a unique identifier and its record is approved in batch release (Annex 1, 8.45).

An alarm asks for a response; an interlock stops an action; a safety function protects people and has its own risk basis.

• 01Design and qualification. Chamber temperature distribution; Probe locations verified against an independent probe (Annex 1, 8.51).
• 02Validation (Annex 1, 8.36, 8.59). Heat penetration for each load type, minimum and maximum loads; Equilibration and exposure time, pressure–temperature correlation; Biological indicators at worst-case locations.
• 03Routine. Cycle records with unique identifiers; Air removal and leak tests; Load dryness and packaging checks.
• 04Periodic. Revalidation of worst-case loads at least annually (Annex 1, 8.39).
• 05Change. Revalidation after changes to the load, packaging or cycle.

• 01EU GMP Annex 1: Manufacture of Sterile Medicinal Products — European Commission (EudraLex Volume 4), 2022 revision, in operation 25 August 2023. EU / EEA; revised jointly with the PIC/S Committee; in force. Supports: Sterilisation principles, load patterns and revalidation (8.34–8.45); heat sterilisation records and probes (8.50–8.53); moist heat cycles, leak and air removal tests (8.55–8.65).
• 02EU GMP Annex 15: Qualification and Validation — European Commission (EudraLex Volume 4), 2015. EU / EEA; in force. Supports: Equipment qualification and process validation approach.