INSTRUMENT MANUAL
VACUUM GAUGE MODEL MM200
160Phone:(215) 947-2500 fax:(215) 947-7464 e-mail:sales@televac.com web site:www.televac.com
MM-200_im REV M
Page 131 of 160
PROCEDURE FOR ON-SITE VACUUM CALIBRATION OF TELEVAC MODULAR MM200 INSTRUMENTS
1. Install the master gauge tubes on the vacuum chamber in a location, which will allow the
master gauge tubes and the vacuum chamber gauge tubes to see the same pressure under
static test conditions. To achieve this, we recommend that a "T" be installed on each vacuum
chamber. (See figures).
2. Pump the chamber down to a pressure of less than 10
- 4
Torr.
3. On the main chamber thermocouple gauge (usually TC#1), adjust the "zero adjust" ("heater
adjust") potentiometer to bring its reading into agreement with the master gauge TC#1. It
should read at " 0.0" ("red line") on the MM200 instrument.
4. Close the main valve. Slowly bleed dry nitrogen into the chamber until a pressure of 1 micron
is observed on the master thermocouple gauge. Observe the gauges for a minimum of 2
minutes. Leak up should be minimal before proceeding. If not, determine the source of the
leak and correct it.
5. Check the thermocouple readings at 1, 10 & 150 microns. Under the conditions of field test, at
the vacuum chamber, the following tolerances should be observed:
1 + 1 micron
10 + 2 microns
150 + 30 microns
Record the data. Readjust, if required, and record new data.
6. With the pressure at 1 micron (10
-3
Torr ), observe that the readings on the cold cathode gauge
of the vacuum chamber instrument, fall between 8 x 10
-4
and 3 x 10
-3
Torr.
Minor adjustment of the gauge can be made to show agreement with the thermocouple gauge
at 1 micron.In order to do this, adjust the cold cathode " 10
-3
" potentiometer to give a meter
reading of 1 x 10
-3
Torr.
Record data.
7. Place calibration sticker on instrument.
8. Remove the master gauges from the vacuum chamber and replace the plugs in each
calibration "T".
To Next Page
Loading...