Parameters
GA 09.035/6.02 - 07/2011 - © Oerlikon Leybold Vacuum
49
Characteristic curves
Fundamentally we have to distinguish between logarithmic and linear charac-
teristic curves. A logarithmic characteristic curve is useful if the pressure range
covers several orders of magnitude in the measurement. In this case it is
appropriate to take the logarithm of the pressure and then scale the result in a
suitable manner.
A linear characteristic curve is useful if the pressure range covers only a few
orders of magnitude in the measurement. In this case the recorder output volt-
age is proportional to the pressure value. You can specify which pressure
value will result in the maximum output voltage.
The available characteristic curves will be described in the following. In each
case it is shown how to calculate the pressure p (in mbar) from the recorder
output voltage U (in volts).
LoG
Logarithmic representation of the entire measuring range.
LoG A
Logarithmic representation of the entire measuring range (compatible with the
A series).
LoG -6
Logarithmic representation of a partial measurement range (2.5 V/decade).
Transmitter
Pressure (in mbar)
TTR
p = 10^[U/(10/7) - 4]
TTR 100
p = 10^[U/(10/7) - 4]
PTR
p = 10^[U/(10/7) - 9]
PTR 90
p = 10^[U/(10/12) - 9]
CTR
p = 10^[U/(10/4) - 4] * FS
ITR
p = 10^[U/(10/12) - 9]
Transmitter
Pressure (in mbar)
TTR
p = 10^[U/(10/6) - 3]
TTR 100
p = 10^[U/(10/7) - 4]
PTR
p = 10^[U/(9/7) - 9 - 7/9]
PTR 90
p = 10^[U/(10/11) - 8]
CTR
p = 10^[U/(10/4) - 4] * FS
ITR 90
p = 10^[(U - 7.75)/0.75]
ITR 200
p = 10^[U - 8]
Transmitter
Pressure (in mbar)
All types
p = 10^[U/(10/4) - 10]
