DILUTING AND MEASURING DEVICE FOR PARTICLE COUNTING

摘要

A device for particle counting includes means (21) for metering a volume of a liquid sample containing particles and a cylinder (33) for dosing a volume of a diluting liquid to a dilution chamber (72). The cylinder (32) has first and second ends and a piston (33). A conduit (18) connects a first end of the cylinder and the dilution chamber (72). The metering means (21) introduces the liquid sample in the conduit (18) and movement of the piston (33) towards the first end displaces diluting liquid and sample to the dilution chamber (72) which communicates with the second end of the cylinder (33) and is preferably located therein, whereby movement of the piston (33) towards the second end causes pressurising of the dilution chamber to displace diluted sample from the dilution chamber through a particle counting means (73). The piston (33) has a piston rod (34) extending through the first cylinder end, whereby movement of the piston towards the first end causes an increase in volume (V2) in the cylinder on the second piston side that is greater than the decrease in volume (V1) in the cylinder on the first piston side. The increase causes a lowered pressure on the second piston side that draws air into the dilution chamber.