VACUUBRAND VAP 5 - Manual (Page 8)

page 8 of 17
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.: 999039 / 16/12/2009
Description VAP 5
The vacuum gauge VAP 5 relies on the fact that the thermal conductivity of the residual gas in the vacuum
chamber is a measure for the gas pressure. The thermal conductivity of gases is proportional to the
pressure within a certain range and is related to the molecular mass.
The thermal conductivity of gases and vapours varies with their molecular mass. The gauge has been
adjusted for air (nitrogen) at the factory.
☞ Pressure of gases with similar mass, such as O
2
or CO, can be read off directly within the uncertainty
of the measurement.
☞ With gases of lower or higher mass (H
2
, He, Ar, CO
2
) it is advisable to readjust the gauge head, primarily
at atmospheric pressure, using the gas to be measured, see section “Readjusting the gauge head“.
Description DVR 5
The DVR 5 is equipped with a ceramic pressure transducer to measure the actual pressure according to the
capacitive principle of measurement independent of the gas type and depending on the vacuum, i. e.
absolute. Electrically, the pressure transducer corresponds to a plate capacitor. A change in capacity
indicates a pressure change.
The pressure value is displayed with a resolution of 0.1 mbar in the range of 0.1 to 10 mbar and with a
resolution of 1 mbar for pressures > 10 mbar.
Preparing for operation
➨ ➨ ➨ ➨ ➨ Connect gauge head with connecting cable to the female connector at the rear side of the equipment.
Screw the plug into the female connector.
➨ Connect the gauge head to the vacuum chamber via the small flange connection or a hose nozzle.
Avoid contamination (oil/oil mist) of the gauge head when generating the vacuum with an oil-filled
vacuum pump.
☞ Do not mount the gauge head directly at the pump. The diameter of the pipelines should be as large as
possible.
➨ ➨ ➨ ➨ ➨ Switch on the equipment.
☞ After switching on the vacuum gauge, an internal check and adjustment routine starts automatically
(indicated by the clock symbol and “CAL“ in the display).
How to change the pressure unit
The vacuum gauge comes switched to the mbar-scale (230 V version) or Torr-scale (110 V version). To
convert reading to mbar, Torr or hPa:
➨
➨ ➨ ➨ ➨ Press key-button by using a small screwdriver or the tip of a pencil (and hold) during switching on.
➨ ➨ ➨ ➨ ➨ “Set“ and the pressure units (mbar, Torr, hPa) are displayed, the pressure unit as from last operation is
flashing.
➨ ➨ ➨ ➨ ➨ Press key-button to change pressure unit. Approximately 2 sec. after the last tip the mode is termi-
nated.
Serial interface
The vacuum gauge DVR 5 is equipped with a serial interface at the rear side of the housing.
☞ Respectively plug-into or remove the cable from the interface (cable RS 232C, 9-pole, Sub-D) only if the
equipment is switched off.
☞ The interface is not electrically isolated from the measuring circuit.