Mcleod Vacuum Gauge measures absolute vacuum in its very last stages.
This gauge avoids use of a movable reservoir of mercury and also requires only about 14 cc. of mercury for first filling.
The total size of this gauge is about 9” x 6”.
Metallic stand with Rotating arrangement & 1 st fill mercury is provided.
The system of which vacuum is to be measured, is connected by flexible rubber tubing to nozzle on the back centre of gauge at A.
Gauge is in Horizontal position-1 initially.
To take vacuum reading, gauge is to be rotated in the vertical position-2.
Mercury runs out of the container B, compressing the residual air or gas contained within region C & D, to short length of capillary tube C & E.
By arranging that the level in the comparison capillary F is opposite the end of the graduated capillary C & E, slight adjustment of gauge above the vertical axis is needed to adjust the mercury level correctly.
Reading in tube C-E is absolute Vacuum in mm of Hg in your line.
Gauge is portable & so one gauge can be used to counter check absolute vacuum at different places.
Very helpful to know that permanently mounted Dial Type Pressure gauge or U-Tube high vacuum manometer or any other gauge is giving correct reading or needs maintenance & re-calibration.
Scale is expanded from 1.0 to .001 torr and so minute reading in very last stages becomes possible.
Other vacuum measuring manometer available with us are:
U-Tube Absolute High vacuum manometer with Attached Catchpot, measure vacuum in last stages from 660 mm to 760 mm Hg., in stapes of 1mm Hg.
Full range vacuum manometer, one end open to atmosphere range 0 to 760 mm Hg.
Condenser Vacuum gauge with Attached Catchpot.
Lighting arrangement is optional.