A Bowie-Dick test checks that a pre-vacuum sterilizer is removing air properly before steam reaches the load. In Canada it is expected at the start of each day the sterilizer runs, while most US clinics following AAMI ST79 baseline it weekly. The test is a Type 2 indicator under ISO 11140-5 and it belongs to every pre-vacuum autoclave, not to gravity-displacement units.
What does a Bowie-Dick test actually detect?
A Bowie-Dick test detects air pockets that survive the pre-vacuum stage and block steam from reaching part of the load. The indicator sheet sits in a standardized test pack, and a uniform colour change means the air was removed and steam penetrated evenly. A patchy or incomplete change signals an air-removal failure, which is a sterilizer problem rather than an instrument problem. Because it isolates the vacuum stage, the test can fail even when temperature and pressure gauges look normal, which is why a cycle printout alone cannot replace it. That distinction is the whole point of running it first thing in the morning, before any load is released. A passing sheet does not prove the instruments inside are sterile, because the test measures air removal rather than lethality; it confirms the precondition that lets steam reach every surface. Clinics that treat the test as a formality often discover the gap only when a spore test fails on a unit whose Bowie-Dick sheet looked clean earlier that week.
Is a Bowie-Dick test required daily in Canada?
For pre-vacuum sterilizers, the expectation in Canadian guidance is a Bowie-Dick test at the start of each operating day, before the first load is processed. In Ontario the RCDSO requires a biological indicator for each sterilizer on every day it is used — daily monitoring, not weekly; the Bowie-Dick sits alongside that daily rhythm. The weekly baseline is the CDC / AAMI ST79 standard in most US states, so a schedule borrowed from a US source will under-test a Canadian unit. Gravity-displacement sterilizers do not need a Bowie-Dick test because they do not rely on a vacuum stage to remove air. If your clinic runs both types, the log should make clear which unit receives which test. Where a clinic runs more than one pre-vacuum sterilizer, each unit needs its own daily test and its own log line, since two machines of the same model can age at different rates. Gravity units in the same room never receive the test at all, and the form should make that clear to a new staff member.
Daily versus weekly: what do the standards say?
The two frameworks share the same test and the same interpretation, but they differ on how often it runs and what triggers a retest. Read the table beside your sterilizer manual, because a specific model's requirements can be narrower than the general baseline, and the manufacturer's instruction governs where the two differ.
| Question | Canada (provincial + CSA Z314 series) | US (CDC / AAMI ST79) |
|---|---|---|
| Typical frequency | Start of each operating day on pre-vacuum units | Weekly baseline in many states |
| Which sterilizers | Pre-vacuum only | Pre-vacuum only |
| Test type | Type 2 indicator, ISO 11140-5 | Type 2 indicator, ISO 11140-5 |
| After a failure | Investigate, correct, then re-test before releasing loads | Investigate, correct, then re-test before releasing loads |
| Records | Logged daily with the cycle record | Logged with the weekly spore test |
What should you do when a Bowie-Dick test fails?
Halt releases from that sterilizer until the cause is found. The usual suspects are a worn door gasket, a blocked or damp drain line, a failing vacuum pump, or an overloaded chamber that the pre-vacuum stage cannot clear. Re-run the test after correcting the fault, and only resume processing once a clean result is recorded. Document the failure, the corrective action and the successful retest in the same log row, because an unexplained gap is what turns a minor fault into an audit finding. If the same unit fails twice in a week, call for service rather than repeating the test until it passes. A retest that passes does not erase the original failure; keeping both records makes the pattern visible if the same fault returns weeks later.
Do rapid-readout spore tests change the schedule?
No. A rapid-readout biological indicator shortens the wait for a spore result, but it does not change how often the test is due. In Canada that is still daily for each sterilizer in use; in most US states it remains the weekly baseline. Where a clinic runs both the daily Bowie-Dick and a daily spore test, the two records should sit together so a reviewer can see the whole day in one place. Matching a rapid spore test with a same-day air-removal result is the fastest way to demonstrate that the unit was working when the load was released. What changes with a rapid indicator is the wait for a result, not the obligation itself, and the cadence still attaches to the sterilizer rather than to whichever indicator happens to be on the shelf that month.
Stocking for a daily cadence
A six-pack of Type 2 test packs will not carry a busy clinic through a month of daily testing, so most offices keep a larger reserve on hand. A dedicated Bowie-Dick daily vacuum check pack keeps the morning routine simple, and a 100-pack of 24-hour rapid-readout biological indicators covers the matching daily spore test. Running the two tests together each morning keeps the log consistent and the release decision defensible.
Ordering for a clinic, lab or care home? Wholesale and multi-site ordering covers case pricing and account setup, and the B2B wholesale collection lists the lines stocked for institutional buyers.
Related Reading
- Air removal testing pre vacuum autoclaves daily bowie dick requirements
- Aami st79 vs csa z314 8 steam sterilization guidance compared
Not sure which consumable fits your set-up? Start with the BI 5-pack trial (CA $12.99, shipping included).
Take this further: print the free sterilization log and record templates, run the cycle log generator, or ask a compliance specialist to review your setup.
Frequently Asked Questions
Which autoclaves need a daily Bowie-Dick test?
Any pre-vacuum sterilizer does. Gravity-displacement units do not use a vacuum stage, so the Bowie-Dick test does not apply to them.
Can a Bowie-Dick test replace a biological indicator?
No. The Bowie-Dick test proves air removal and steam penetration, while a biological indicator proves lethality. They measure different things and both are needed.
Where does the Bowie-Dick test pack go in the chamber?
Place it on the bottom rack, near the front, in an otherwise empty chamber, following the manufacturer's instructions for that sterilizer model.
CliniEco Medical is a licensed medical device establishment (MDEL #35334).
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