Why is aspiration slow and incomplete?
Reasons for slow or incomplete aspiration are 1) poor vacuum source, 2) leaking vacuum bottle and tubing, 3) leaking aspiration valves or 4) damaged/clogged dual tube system of the processing head. • The vacuum source should be about 400 mmHg (16″Hg) with all valves closed. The amount of vacuum pressure needed depends on the composition of the samples harvested and the characteristics of the filter mat. The recovery time of a vacuum pump or in-house line is important; some will generate a strong initial vacuum but will not maintain a good working vacuum level once the aspiration valves are opened. • Check the vacuum bottles and tubing. Check the bottle cap and make certain it’s hand-tight. Make sure that the tubing attachments to the harvester valve block are secure. The ferrule should be over the tubing end and pushed against the inside of the fitting. Examine all the tubing on the harvester for fit and adjust if necessary. If tubing gets pushed or bent one of the fittings may pull ap
