Granville-Phillips Micro-Ion 354 E Series, Instruction Manual, Page: 23 / 54

Analog Operation
Micro-Ion E Module Instruction Manual 354011, Rev. A
23
Be
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Installa
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Ove
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An
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O
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M
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RS-
232
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tion
Use one of the following equations to calculate N
2
or air pressure as a
function of analog output voltage:
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 4-3 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
pressure units, the correction factor is 0.30, and the
actual pressure of the neon is 1.67 x 10 –4 pressure units:
4.8 Overpressure Limit
The Micro-Ion E gauge shuts off if pressure exceeds 1 x 10
–2
Torr (1.33 Pa,
1.33 x 10 –2 mbar). You cannot adjust the overpressure limit.
Pvacuum
(Torr)
10
Volts 10 –
( )
=
Pvacuum
(mbar)
1.33 10
(Volts 10
)
–
×
=
Pvacuum
(kPa)
1.33 10
(Volts 11
)
–
×
=
Indicated N
2
or air pressure
Correction factor
----------------------------------------------------------------------- Actual pressure =
Table 4-3 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
–
pressure units
0.30
-----------------------------------------------------------
1.67 x 10
4
–
pressure units
=