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5. Bowie-Dick Tests and Troubleshooting Guide

KNOWLEDGE CENTER

January 8, 2020

 

Bowie-Dick Tests and Troubleshooting GuideWHAT IS A BOWIE-DICK TEST?Bowie-Dick (Air-Removal) tests evaluate the performance of prevacuum sterilizers by confirming adequate air removal from the sterilizer chamber. These air removal tests have been improved over the years, but you may be wondering, are Bowie-Dick tests still relevant in sterilizers that have programmed leak tests?

To fully answer why this test is still important today, we must first understand why it is important to remove air from the sterilizer. Air within a steam sterilizer is often referred to as a non-condensable gas (NCG). As the name indicates, non-condensable gases do not condense when touching a colder item. These gases act like a shield between the steam and the item, potentially shielding bacteria and preventing proper sterilization.

Even today’s sterilizers are not capable of detecting NCG because it could be hiding anywhere in the chamber. Sensors would need to be placed within the packs exactly where the NCG would either be trapped or collected in order to detect it. This is not possible and supports why air-removal tests are still very relevant to today’s modern sterilizers for autoclave testing. The Vacuum Leak Test programmed on your autoclaved only measures the integrity of the sealed pressure vessel and associated piping to assure air is not being admitted to the sterilizer during the vacuum draw downs.

In addition to air-removal, modern Bowie-Dick Tests such as the VERIFY® Bowie-Dick Test Pack provide a critical control for sterilizer performance and verification of steam quality. It ensures the sterilizer can provide the validated preconditioning required, and aid in detection of steam quality that could interfere with sterilization of complex instrumentation.

chemical indicator, any substance that gives a visible sign, usually by a colour change, of the presence or absence of a threshold concentration of a chemical species, such as an acid or an alkali in a solution. An example is the substance called methyl yellow, which imparts a yellow colour to an alkaline solution.A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually. Hence, a pH indicator is a chemical detector for hydronium ions (H₃O⁺) or hydrogen ions (H⁺) in the Arrhenius model. Normally, the indicator causes the color of the solution to change depending on the pH. Indicators can also show change in other physical properties; for example, olfactory indicators show change in their odor. The pH value of a neutral solution is 7.0 at 25°C (standard laboratory conditions). Solutions with a pH value below 7.0 are considered acidic and solutions with pH value above 7.0 are basic. Since most naturally occurring organic compounds are weak electrolytes, such as carboxylic acids and amines, pH indicators find many applications in biology and analytical chemistry. Moreover, pH indicators form one of the three main types of indicator compounds used in chemical analysis. For the quantitative analysis of metal cations, the use of complexometric indicators is preferred,^[1][2] whereas the third compound class, the redox indicators, are used in redox titrations (titrations involving one or more redox reactions as the basis of chemical analysis).A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually. Hence, a pH indicator is a chemical detector for hydronium ions (H₃O⁺) or hydrogen ions (H⁺) in the Arrhenius model. Normally, the indicator causes the color of the solution to change depending on the pH. Indicators can also show change in other physical properties; for example, olfactory indicators show change in their odor. The pH value of a neutral solution is 7.0 at 25°C (standard laboratory conditions). Solutions with a pH value below 7.0 are considered acidic and solutions with pH value above 7.0 are basic. Since most naturally occurring organic compounds are weak electrolytes, such as carboxylic acids and amines, pH indicators find many applications in biology and analytical chemistry. Moreover, pH indicators form one of the three main types of indicator compounds used in chemical analysis. For the quantitative analysis of metal cations, the use of complexometric indicators is preferred,^[1][2] whereas the third compound class, the redox indicators, are used in redox titrations (titrations involving one or more redox reactions as the basis of chemical analysis).

Autoclave tape is an adhesive tape used in autoclaving (heating under high pressure with steam to sterilise) to indicate whether a specific temperature has been reached. Autoclave tape works by changing color after exposure to temperatures commonly used in sterilization processes, typically 121°C in a steam autoclave.

zer monitoring, PCDs containing BIs are also used for other applications as listed below:

• Routine monitoring of non-implant loads
• Routine monitoring of implant loads. AAMI ST79:2017 recommends using a PCD containing a BI and a Type 5 integrating indi