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• • How do I carry out the evacuation/replacement technique using the Oxoid Anaerobic Jar?
  • How do I use an Anaerobic Jar with a Gas Generating Kit?
  • How should I clean my anaerobic jar?
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DIRECTIONS FOR USE IN EVACUATION/REPLACEMENT TECHNIQUE

1. Place the Petri dishes in the carrier.
Disposable plastic Petri dishes should be of the vented variety to aid gas transfer between the interior and exterior of the dishes.

2. Cut open an Oxoid Anaerobic Indicator (BR0055) and expose 10mm of the fabric strip. Insert the sachet into the smaller, upper clip on the dish carrier.

3. Lower the dish carrier into the polycarbonate base.

4. Place the lid on the base making sure that the O-ring is correctly in place, evenly pressed against the flange as a secure fit. Apply the beam clamp. This is easily done by first holding the beam over the flange on the lid and parallel with two Schrader valves. Move it horizontally with the top of the beam slightly inclined towards the gauge and safety valve, so that the screw thread passed between the two Schrader valves to the location point on the lid centre.

5. Oxoid modified Schrader chucks (Oxoid Code HP0020) have to be used for the evacuation/replacement technique to enable a vacuum to be drawn. One chuck is fitted to the vacuum line and one to the gas supply by means of the clips provided. The ‘input’ Schrader valve has a metal nozzle to ensure that incoming gas enters at the bottom of the jar to improve mixing of the hydrogen with the residual oxygen.

6. Fit the chuck connected to the vacuum line to the Schrader valve marked ‘Vacuum’ or ‘V’ as follows:
Depress the side arm on the chuck body and PRESS (not screw) the open end of the chuck firmly down on to the valve body.
Screwing will damage the sealing rubber washer and cause the chuck to leak.

While maintaining a firm downward pressure on the body of the valve, release the side arm of the chuck. This will clip the chuck firmly and without leakage on to the valve.

7. Evacuate the system to about – 0.6 bar. The knurled wheel on the beam must not be further tightened if it appears loose.

8. After use, simply depress the side of the chuck and lift straight away from the valve in order to disconnect it. Observe the pressure gauge. A leaking jar will be detected at this stage because the vacuum reading will not remain constant.

9. Attach the chuck connected to the gas supply to the input valve of the jar. Run the gas mixture into the jar until the pressure is zero. Disconnect the chuck.

10. Observe pressure changes in the jar. With an active catalyst a secondary vacuum will be formed, indicated by a fall in pressure to – 0.2 bar in 5-10 minutes.

11. Add more gas mixture to the jar until the gauge reads zero. Disconnect the chuck. Incubate the jar.

12. The Anaerobic Indicator will change from pink to white in 2-3 hours. This will give the visual indication of anaerobiosis.

13. After incubation the Anaerobic Indicator should be discarded with the normal laboratory litter.

14. The catalyst should be dried between uses by heating to 160°C for 90 minutes.

15. Store the jar with the lid inverted so that the catalyst will remain dry when not in use.

The interior of the lid and jar should be kept free of dust.