Detailed introduction of medical dry-blocking microbial penetration performance tester

Medical fabric drying state microbial penetration tester

A large number of examples have shown that bacteria can penetrate barrier materials along with dry organic or inorganic particles, such as dander or clean clothes carrying bacteria, and bacteria-carrying particles penetrating packaging materials during storage. This instrument can be used to determine the material’s resistance to bacterial penetration on dry particles within the size range of human dander.

1. Testing principle of medical clean clothing dry microbial penetration tester

The tests were carried out on specimens respectively fixed on a container. Among these containers, 5 contained talc containing Bacillus subtilis and one containing talc without infection served as a control. Insert a petri dish at the bottom of each container close to the test piece. The equipment supporting the container is vibrated by a gas ball oscillator. All the talcum powder that penetrates the specimen falls onto the Petri dish. The Petri dish is taken out and cultured.

2.Test standards

The dry-resistant microbial penetration tester tests samples according to ISO 22612 and YY/T 5056.5 test standards.

3. Composition and use of instruments

The instrument is completed in strict accordance with the standard drawings and fully complies with and can achieve the test content required by the standard.

The instrument contains:

(1) Pneumatic ball oscillator: The external air source passes through the pneumatic ball oscillator, and the vibration frequency is maintained at the target frequency through corresponding adjustments and corrections. It can produce 20,800 vibrations per minute with a force of 650N.

(2) Compressed air flow meter: It is mainly used to measure the air flow that generates 20800 (347Hz) vibration frequency per minute.

(3) Test container: This instrument has 6 stainless steel test containers with metal pistons on the top. The metal piston can be inserted through the center hole on the cover to reach 10mm below the cover. Make sure that the specimen is not loose after insertion. At the same time, the bottom attachment of each container has a narrow opening for inserting a petri dish.

(4) Marble board: Marble with an area of ​​400mm*400mm and a thickness of 10mm is used as the operating platform of the entire instrument.

(5) Fixing plate: a stainless steel plate with 6 holes, fixed on the stone plate with a clamp, used to fix and install the test container

(6) Rubber supports: With 4 rubber supports, they are used to adjust the level, fix the position of the instrument and prevent movement.

test

1. Analysis of test steps: This test is conducted on specimens fixed on a container. Among these containers, 5 containers carrying Bacillus subtilis talc served as the test group, and 1 container containing uncontaminated talc served as the control. Insert a petri dish at the bottom of each container close to the bottom of the test piece. The equipment supporting the container is vibrated by a gas ball oscillator. All the talcum powder that penetrates the specimen falls onto the Petri dish. Take out the Petri dish and incubate it. The number of growing colonies was counted.

2. Equipment debugging: Ensure that the dry-blocking microbial penetration tester is operable.

(1) Adjust the level. According to the level, adjust the 4 rubber supports so that the instrument is in a horizontal position.

(2) Adjust the frequency of the gas ball oscillator to achieve a vibration frequency of 20,800 times per minute.

3. Sample preparation: (1) Cut 12 pieces to be tested. The size of the 12 samples is 200mm×200mm. (2) Sterilization: Sterilize the cut specimens and each test container. (3) Fix the test container. Fix the test container on the fixed plate through the rubber ring so that it is closely connected to the fixed plate and the bottom is against the stone plate. (4) Talc powder preparation. Prepare talc powder containing AATCC 9372 Bacillus subtilis spores. The concentration should be about 108CFU/g. The preparation process refers to YY/T 5056.5-2009.

4. Start experimenting. Use sterile operation methods to take out the test piece and place it on the mouth of each test container. The lid is secured to the container by pushing down on the piston so that the specimen is secured with a controlled degree of slack. Remove the piston. Add 0.5g±0.1g of bacteria-contaminated talc powder to the test piece through the piston port, and add uncontaminated talc powder to the sixth container as a control. Seal the piston mouth with tape. Place a small plastic bag over each container. Insert a lidless Petri dish through the slot in the bottom of each container. Seal the slit with adhesive tape. Vibrate at a vibration frequency of 20,800 times per minute for 30 minutes. Remove plastic bag and adhesive tape.

Insert the lid of the Petri dish through the slit, remove the Petri dish and incubate at 35°C for 24 h. Count the colonies that form. A valid sample should be a reference plate with a reading of 0. Otherwise, it means there is external contamination, and the test should be stopped. Repeat the above experimental steps. Test at least 2 groups, and calculate the arithmetic mean of 10 valid results as the final result. When the experiment is over, make sure the data has been recorded and adjust the voltage regulator knob on the panel to 0 scale. Close the air inlet device of the instrument, turn on the exhaust fan and lighting, and clean the surface of each sample box.

5. Maintenance

To ensure normal use of the instrument and extend its service life, please keep the instrument dry. And use it in a relatively dry environment to avoid water droplets splashing or condensation, so as not to damage non-water-resistant components. If the instrument is not used for a long time, please disconnect the power supply and cut off the air source. The internal starting oscillator of the instrument is a vulnerable component. When the service life is reached, the accuracy of the oscillation frequency will decrease. It is recommended to replace new parts at this time. At the same time, if the marble slab is damaged, please replace the accessories of the same specification in time.

In order to prevent contamination of test personnel and the test environment, test personnel need to have a basic knowledge of microbial culture. Follow laboratory operating procedures carefully.