HP T100 Operations Instructions download pdf (Page 10)

4. Operation

4.1. General

Once voltage has been supplied the transmitter is ready to operate. A stabilization time of 5-

10 minutes must be considered of. It is usually better to ensure that the transmitter remains in

operation all the time.

Use Of The Filament Protective Panel

During normal UHV applications, the transmitter can be operated without the filament

protection.

When applications are involved where greater levels of contamination are anticipated, the

protective panel, which is included, must be used. It is important to observe the necessity for

cleanliness when fitting the panel. The conductance value of the transmitter is reduced when the

panel is used. In this case, operations should be restricted to 7.5 x 10

-6

Torr (1 x 10

-5

mbar).

The measured pressure depends on the type of gas. For matching to various types of gas a

respective gas correction factor for the Pirani or Bayard-Alpert unit can be set; this generates the

correct measurement value in the pressure range below 7.5 x 10

-3

Torr (1x 10

-2

mbar). The gas

type correction factor for air and N

has been set in the works to 1.00 (please also refer to Section

8.3.”Gas Correction Factor”).

The transmitter has been factory adjusted. Re-adjustment may be necessary in the event of

extreme temperatures or ageing etc. and is carried out with a connected vacuum controller

via the PC-Software "DokuStar" or customer specific in accordance with the communication

instructions.

Please note that before equalization the transmitter must have been in operation for

approximately 5 minutes (warm-up time) at the respective pressure. For correct zero point

equalization, the pressure in the vacuum chamber must be below 3.75 x 10

-5

Torr (5 x 10

-5

mbar).

Baking out

If the bakeout temperature is higher than 60°C (140°F) the electronic unit must be removed.

To avoid some mistakes the serial number of the complete unit is fixed up to the transmitter

print.

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HP T100 Operations Instructions Page 10