What is a BD test in a steam sterilizer?


There is a great difference between the latent heat released by saturated steam and unsaturated steam in moist heat sterilization. In order to verify the air removal ability of sterilization cabinet, BD test was born.

Successful B& D tests showed that steam permeated the test package quickly and evenly. Air left in the package may cause the test to fail. Air may be trapped in the package due to the following reasons:

1. Insufficient exhaust stage;

2. Air leakage into the disinfection room;

3. Non-condensing gas exists in the steam supply.

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How to conduct BD test?

The current B-D test method for sterilizers commonly used in medical industry laboratories is the use of disposable B-D test kits.

BD test package is used to test whether the air in the sterilizer is effectively eliminated in the pre-vacuum and exhaust stage. The service conditions are 132℃ ~134℃,3.5 to 4.0 minutes. The test package can be used directly, without the need for staff to make standard package.

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Use of BD test package:

1. Run the heating sterilizer to the appropriate temperature in the empty pot.

2. Place the BD test package at the bottom of the empty pre-vacuum sterilizer, above the exhaust port, generally in the front of the shelf, close to the cabinet door. BD test package must be laid flat with label up.

3. Run the sterilizer for 3.5 minutes (132℃ or 134℃). Any overtime work will affect the B-D test results. Running for more than 4 minutes will cause the test paper to become less sensitive and false-negative results will be observed.

4. At the end of operation, check the B-D test paper.

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Result judgment:

Pass/negative results: The B-D test paper becomes a uniform dark brown to black to show the passing test results. It shows that the air in the sterilizer is removed thoroughly and the steam penetration effect is good.

Failure/positive results: There are bright areas in the middle of the twill of the B-D test paper, showing uneven color, caused by cold air mass in the sterilizer room, indicating incomplete air removal and preventing effective steam penetration. If an uneven color change is found, it must be reported to the supervisor immediately and the sterilizer must be repaired until the troubleshooting is qualified.

Overexposure: If the test paper is gray or silvery, it indicates overexposure (time or temperature exceeding the standard). This is an invalid test and should be retested.

Sterilizer cold air elimination effect will directly affect the cavity in the body temperature, so B – D test qualified is the prerequisite of sterile, made B – D test package should be in accordance with the regulations or use a certificate of approval of a one-time B – D test package, strengthening technical personnel training in order to reduce the effects of technical operations, to equipment maintenance regularly, to ensure the effective supply of sterile articles, Maximize the sterilization effect.


It’s important to know the Bowie-Dick test results. Depending on the test package used, see the instructions for expected results. If you have any doubts about the results, report them to your supervisor, who will decide what action to take. The above is the introduction of BD test in steam sterilizer. If you need to consult the relevant product information, you can contact us. We are a professional sterilizer manufacturer and supplier, providing you with a variety of sterilization methods.

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