Abstract: A helium mass spectrometer leak detector includes a spectrometer tube connected to the inlet of a high vacuum pump. Helium tracer gas passes in reverse direction through the high vacuum pump from the foreline to the spectrometer tube. Relatively high pressure gross leak tests are performed, while maintaining the foreline of the high vacuum pump at the required operating pressure of about 100 millitorr, by passing the tracer gas in reverse direction through one or two stages of a mechanical vacuum pump. Test port pressures up to about atmosphere can be accommodated, with only a single mechanical vacuum pump required. According to another feature, high test port pressures are accommodated using a variable flow restrictor and reverse-connected mechanical vacuum pump in combination.

Abstract: A method and device for handling a fluid to accurately measure the viscosity and/or visco-elasticity of the fluid. More particularly, the method and device hereof is adapted for reliable calibration and filling with a subject fluid, such as blood, enabling accurate measurement even when only a small amount of the subject fluid is available for analysis. Broadly speaking, the device includes a measuring chamber filled with a standard fluid, a coupling chamber filled with a coupling fluid, a flexible diaphragm separating the chambers, and a measuring tube suspended in a downward direction from the coupling chamber. The measuring chamber includes a pressure and flow generating plunger and a pressure sensor; a flow sensor is operably coupled to the measuring chamber. Preferably, the measuring tube is filled with subject fluid by first drawing an air bubble into the tube and then drawing the subject fluid into the tube to completely fill the tube.