ISO 11140-5:2007

Overview

ISO 11140-5:2007 specifies requirements and test methods for Class 2 chemical indicators used in Bowie and Dick‑type air removal tests. These indicators evaluate the effectiveness of air removal during the pre‑vacuum (air removal) phase of pre‑vacuum steam sterilization cycles. The standard defines indicator format, performance, packaging, sampling/conditioning and includes normative annexes describing test packs, steam exposure apparatus and measurement methods.

Key topics and technical requirements

• Purpose: Indicators must detect retained air or inadequate air removal (Bowie and Dick‑type air removal test).
• Indicator format: Indicator agent must be uniformly applied to cover at least 30% of the substrate/test area. Typical indicator system dimensions are 200 ± 20 mm × 275 ± 25 mm.
• Contrast requirement: Substrate ground colour must provide a measurable contrast (reflective density difference ≥ 0.3) between ground colour and changed/unchanged indicator agent (see Annex A).
• Air porosity: Indicator system substrate air porosity ≥ 1.7 µm/(Pa·s) (ISO 5636‑3 method).
• Performance: Indicators must show a uniform colour change after exposure to saturated steam (examples: 134 °C for 3.5 min or 121 °C for 15 min, or manufacturer‑specified equivalents) and must show a non‑uniform colour change under the prescribed standard fault condition in a standard test pack (Annex E) that simulates inadequate air removal.
• Dry‑heat resistance: After exposure to 140 ± 2 °C for ≥30 min, indicator response must be either unchanged or markedly different from steam response (Annex C).
• Transfer and stability: Transfer of indicator agent to the test pack must not compromise results; indicators must comply for the declared shelf life (accelerated ageing procedures allowed).
• Packaging and labelling: In addition to ISO 11140‑1 requirements, indicators and packaging shall be clearly marked for AIR REMOVAL tests.
• Normative test methods: Annexes A–G define measurement methods, fault simulation, standard test pack and steam exposure apparatus.

Applications and users

ISO 11140-5:2007 is used by:

• Sterile processing departments in hospitals and clinics for routine Bowie and Dick testing of pre‑vacuum sterilizers.
• Manufacturers of chemical indicators and sterilization consumables to design and validate Class 2 indicators.
• Quality managers, validation engineers and regulatory compliance teams responsible for sterilizer performance monitoring and documentation.
• Test laboratories performing lot release and performance testing of air removal indicators.

Related standards

• ISO 11140‑1 (General requirements for chemical indicators)
• ISO 11140‑3 / ISO 11140‑4 (Steam penetration tests and alternatives)
• ISO 15882 (Guidance on chemical indicators)
• Relevant measurement standards (ISO 5‑4, ISO 5636‑3, IEC 60751, IEC 60584‑2)

Keywords: ISO 11140-5:2007, Bowie and Dick, Class 2 indicator, air removal test, pre‑vacuum steam sterilization, chemical indicators, standard test pack, sterilization validation.