Granville-Phillips Micro-Ion 354 E Series, Инструкция по эксплуатации, Страница: 32 / 54

Chapter 5
32
Micro-Ion E Module Instruction Manual 354011, Rev. A
RD Read Vacuum Pressure
Send a read pressure (RD) command to read vacuum pressure for N2 or air.
If the process gas is a gas other than N2 or air, you
must apply a correction
factor to determine the actual pressure for the gas that is being used.
N
2
or Air Pressure
The RD command causes the module to return a value that indicates
vacuum pressure for N
2
or air.
RD command from host: RD
↵
Example response from module: 3.50E–04
↵
The example response indicates vacuum pressure for N
2
or air is 3.5 x 10 –4
Torr (4.66 x 10 –2 Pa, 4.66 x 10 –4 mbar).
If the returned value is not a valid representation of pressure, see page 38.
Correction Factor
If the process gas is a gas other than N
2
or air, use the following equation
and the correction factors listed in Table 5-8 to calculate the actual pressure
for the gas that is being used.
For example, if the process gas is neon (Ne), and the indicated pressure for
N2 or air is 5 x 10
–5 Torr, the correction factor is 0.30, and the actual
pressure of the neon is 1.67 x 10 –4 Torr (2.22 x 10 –2 Pa, 2.22 x 10 –4 mbar):
Indicated N
2
or air pressure
Correction factor
-----------------------------------------------------------------------
Actual pressure
=
Table 5-8 Pressure Correction Factors for Commonly Used Process Gases
Process Gas Ar He O
2
CO
2
Kr H
2
O
Correction Factor 1.29 0.18 1.01 1.42 1.94 1.12
Process Gas Hg Xe D
2
Ne SF
6
NO
Correction Factor 3.64 2.87 0.35 0.30 2.5 1.16
5 x 10
5
–
Torr
0.30
----------------------------------
1.67 x 10
4
–
Torr of Ne
=