| 摘要 |
Apparatus is disclosed for dispensing a standardized test fluid used for calibrating a counter while preventing the formation of bubbles in the test fluid and preventing the introduction of extraneous air born particulate contamination, both of which detrimentally affect the calibration. The test fluid is contained in a semi-rigid, ventless container that is partially filled with the test fluid and partially filled with a gas. The container is held in an inverted position by a spring clip attached to the apparatus. The spring clip applies external pressure to the container, partially collapsing same, and thereby pressurizing the gas inside the container above ambient air pressure. A peristaltic pump withdraws the test fluid from the container and precisely meters it through an injection valve and a three way valve to the particle counter. As the fluid is withdrawn the container further collapses to maintain pressurization of the gas. The continued pressurization of the gas allows the pump to precisely dispense the test fluid until the entire contents of the ventless container are dispensed, and at the same time eliminates the formation of a partial vacuum in the container to thereby prevent the formation of bubbles in the test fluid as it is withdrawn from the container.
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