VACUUBRAND VNC 1 - Manual (Page 24)

Documents are only to be used and distributed completely and unchanged. It is strictly the users´ responsibility to check
carefully the validity of this document with respect to his product. Manual-no.: 999118 / 16/12/2009
page 24 of 35
The vacuum gauge was adjusted using factory standards, which are traceable through
regular calibration in an accredited laboratory (German Calibration service) to the na-
tional standard. Depending on the process and/or accuracy requirements, check the
adjustment from time to time and readjust if necessary. For readjustment, the device
has to be adjusted both at atmospheric pressure as well as under vacuum.
Readjustment
Adjustment at atmospheric pressure
Ventilate the controller and/or the vacuum system. Make sure
that the vacuum connection at the controller is at atmospheric
pressure.
➨ Select program ”Cal.Sens” at controller.
➨ Use keys ▲ and ▼ to adjust the display to the actual local
atmospheric pressure.
➨ Confirm value with key ”Enter”.
Note: To determine the actual atmospheric pressure, use an accurate barometer or get accurate reading
from the weather service, the next airport.......(take into account the difference in altitude between e. g.
airport and laboratory).
Adjustment under vacuum
Evacuate the controller via the vacuum connection to a pres-
sure < 0.5 mbar (e. g. by applying a good rotary vane pump).
➨ Select program ”Cal.Sens” at controller.
☞ The display is set to zero automatically.
➨ Confirm value with key ”Enter”.
Note: Adjustment under vacuum with an actual pressure higher than 0.5 mbar reduces the accuracy of the
measurement. If the pressure is significantly higher than 0.5 mbar, adjustment to a reference pressure
(0....20 mbar) is recommended.
Adjustment at a reference pressure
Instead of adjustment under vacuum to a pressure < 0.5 mbar,
adjustment to a reference pressure within the range of 0 ..... 20
mbar is possible.
Evacuate the controller via the vacuum connection to a refer-
ence pressure within the range 0 .... 20 mbar.
➨ Select program ”Cal.Sens” at controller.
☞ The display is set to zero automatically.
➨ Use keys ▲ and ▼ to adjust the display to the actual refer-
ence pressure at the vacuum connection within the range of
0 .... 20 mbar.
➨ Confirm value with key ”Enter”
Note: The accuracy of the value of the reference pressure will directly affect the accuracy of the adjustment.
If the nominal ultimate vacuum of a diaphragm pump is used as reference vacuum, the accuracy of the
controller might be doubtful. The diaphragm pump may not achieve the specified value (due to condensate,
poor state, failure of valves or the diaphragm).
1013mbar
0mbar
0....20mbar