Air Pumps

AIR PUMPS

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Air Pumps, 64ul, general information (9-17-08)

Just wanted to pass along some observations I've recently made regarding Air Pumps that are used on MAXM's, HMX's, and LH 500's. We have had a few accounts experience failures, with the replacement air pumps also not performing as well as expected. Since then, I've been observing as many systems as I can to learn what is normal operation and the best way to verify that the air pump is functioning properly.

If you observe port 11 of the BSV, which has the tubing going to the mixing chamber attached, you should see a slug of blood forced out of the BSV into the tubing, followed by approximately 1/4 " of air, as soon as the pinch valve for the air pump fires (pv 13). The key is to look for that 1/4" of air, which indicates that all of the blood has left the BSV. The slug of blood should hesitate momentarily, less than a second, before the Erythrolyse pump fires and sends the sample to the mixing chamber.

On systems that have marginal air pumps, I have not seen the 1/4 " air gap or am missing the slight hesitation with the slug of blood remaining in the line before the Erythrolyse pump fires. The main symptom is increased PC1 diff failures due to an extended counting time caused by too little blood going to the mixing chamber. On instruments with gross failures, you notice the sample in the mixing chamber is lighter in color, but on systems with marginal failures, it's difficult to gauge if there is enough blood in the chamber. Observing the sample at port 11 is a more effective method in determining proper instrument operation.

For troubleshooting purposes, until I have access to a replacement pump, I've had success adjusting the pump's volume up, until I can see the air gap. This also assumes that all ports of the BSV and the sample loop have been bleached out as part of the troubleshooting process. Submitted by Rick Graber, CSS

Additional observations: Looking at the diff scatter plot, the scatter plot looks completely normal but the densities of each population is not as great, especially when the amount of blood is not sufficient. No debris is noted at the bottom. It may count 8k cells but the count time is too long or it may count less than 8K with a count time of 30sec (max.) resulting in PC1 errors.

I have had 1 account where we increased the air pump volume quite a bit to get that 1/4". After bleaching out the diff ports in the BSV, the 1/4" turned into 1" or more and the new pump had to be readjusted back to its original setting.

Submitted