Air bubbles

If this always occurs in the same pipette, check the bottom of the pipette for the following:

1. Glass may be chipped.
   • Replace pipette.
2. Dirt, e.g. dried blood.
   • Clean the pipette.
   • Check disinfectant flow at the rinse nozzle.
3. Perpendicularity and straightness of the bottom face.
   • Replace pipette.

If this happens randomly or with each pipette, check the following:

1. Fill nozzle O-ring or flat washer.
2. Fill nozzle alignment to pipette.
   • Check the nozzle arm is tight on the rear vertical shaft. Usually engineer’s assistance is required.

A pipette which looks like zebra crossing gives ESR Error 3.

The filling (aspiration) speed is not critical but should be within certain limits.

1. If just one air bubble is found about 5mm below the meniscus, the filling speed may be too high.
2. The blood column should not exceed the Fill stop sensor by more than 10mm.

One air bubble can result in ESR Error 3.

1. Usually this is caused by a wet or dirty fill nozzle.
   • The blood column should not reach right to the base of the pipette. There must be a clear air gap of 4...5mm at the bottom of each pipette.
2. Insufficient sample volume.
   • Need more blood in the sample tube.

One air bubble rising can result in ESR Error code 3.

A layer of air bubbles that is concentrated on top of the blood column does not affect the sedimentation process itself. The sedimentation develops normally below the bubbles. However, too many bubbles bring about a shortening of the effective blood column, which is a deviation from the Westergren method.

A layer of bubbles up to 5 mm: No message. Normal ESR result is reported.

A layer of bubbles from 5 to 25 mm: ESR warning 6: "Bubbles on top". Results should be reviewed before release.

A layer of bubbles larger than 25 mm: ESR Error 3: "Too many borders found". No ESR result is given.

1. Check that tube connections are not leaking.
2. Check the fill nozzle condition:
   • Inspect for any cracks or deep scratches in the base that holds the fill nozzle washer or O-ring.
3. Check for air in diluter system.
4. Check that the sample probe O-ring is not leaking.
5. Check transparent mixing- piece block for cracks.

Usually this is caused by a dirty or damaged fill nozzle.

• Observe the maintenance schedules.
• Clean the fill nozzle.
• Check the fill nozzle for damage. If necessary, replace the fill nozzle.

Sample tube is leaking on the fill nozzle side.

• Replace the silicon sample tube

Small air bubbles result in ESR Error 3.

When air bubbles are seen after filling.

This can be caused during preparation of the sample. If the sample tube is, not mixed or inverted well air can arise in the blood. This causes an air bubble occurs in the pipette.

According to the ICSH, a sample should be gently inverted at least eight times. Do not shake the sample.

1. Check Diluent flow by priming the diluter system.
2. Insufficient sample volume.

Random air bubbles result in ESR Error 3.