Vacuum control to pressures of 10-8 mm Hg

Information on vacuum controllers for the medium and high vacuum ranges is scarce. Laporte [49] has described an instrument working on the thermal conductivity principle in which the Wheatstone bridge is connected to a signalling device which produces an acoustic signal when the pressure exceeds a given value. 

Melpolder s apparatus for pressure control in the range 10 to 10 torr 

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