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Re: Vacuum Pump




From: 	Larry Robertson[SMTP:LWRobertson-at-msn-dot-com]
Sent: 	Sunday, July 13, 1997 12:28 AM
To: 	Tesla Builders
Subject: 	re: Vacuum Pump

Chip ... congratulations on getting the list back up, we missed it.

Doug, the following information is from the Oxford Instruments
vacuum manual.

1 mmHg is the force exerted by a column of mercury 1 mm high.
1 torr = 1 mmHg.
760 torr is one atmosphere.
One atmosphere is also 30 inches of Hg.

1/1000 torr is one micron ( 1/1,000,000 meter or 1/1000 mm ).

A single stage rotary pump should easily reach 100 microns, and
might eventually reach 10 or 20 microns if it is in good shape
and the oil is clean.

Under "High Frequency Pressure Testers" in the same manual
it says " When the probe of a h.f. generating unit is placed close
to the wall of a glass vacuum system a discharge is produced
inside, the appearance of which depends upon the gas and its
pressure"

It continues with a chart:

Discharge in Tube                        Approx. Pressure
Pink glow                                    10 mmHg
Striations commence                    1.5 mm
Striations 1 cm apart                     0.5 mm   ( 500 microns)
Green fluorescence                       0.01 mm  ( 10 microns)
Blackout                                      0.001 mm ( 1 micron )

These would be very approximate, I suspect. Looks like 
your pump should work for making glow tubes and such,
and will be fine for pumping capacitors, but won't produce
a hard vacuum definatly.

LR