Servomex SERVOTOUGH LaserExact 2950, Operator'S Manual

Page: 37 / 72

SERVOTOUGH LaserExact Monitor, Operator Manual 02950001A_1
SERVICE PROGRAM
31
chamber can be specified, whereas the pressure is assumed the same as in the
sample gas.
Note: The gas temperature and the optical path length through the laser beam
alignment chamber are specified with the parameters <G
AS TEMPERATURE IN
FLANGES
> and <O
PTICAL PATH THROUGH FLANGES
>. The temperature must be
specified as accurately as possible.
Temperature sensors inside the cabinet measure the ambient air temperature. The
ambient pressure is either measured by the internal pressure sensor or assumed
to be equal to 1.013 bar (760 mm Hg = 1 atm) if it is not installed.
After specification of all optical path variables the gas concentrations in the laser
beam alignment chamber and transmitter unit must be specified in the <G
AS
SPECIFIC PARAMETERS
> menu.
Note: Proper setting of the optical path parameters is important for correct
measurements.
Concentration averaging
The amount of primary measurements used to calculate the averaged
concentration (
Concentration Avg in Measurements menu). The instrument
measures and calculates the gas concentration at regular intervals. A primary
measurement (
Concentration Instant in Measurements menu) takes
approximately 1-4 seconds depending on the gas type. The instrument calculates
a “running” average of the primary measurements, which is then output in the
following three ways: 1) printed on the display in the electronics unit, 2) driven
through the 4-20 mA analogue output, and 3) transmitted as a digital signal in the
optical fibre output (optional). All these output channels use the averaged gas
concentration. The display and the current loop are updated after every primary
measurement, while new data is transmitted through the fibre optic output after the
defined averaging time. The amount of averaging is specified by the averaging
count (T
av
= N x T
prim
).
Line width averaging:
Specifies the number of line width averaging.
Line width adaptive averaging:
Switched OFF = the rolling average (as for concentration) applies.
Switched ON = the number of averaging depends on the signal strength i.e. weak
signals are averaged longer. NB: This will only be effective if line width averaging
is specified > 10.
Spectral temperature averaging:
Specifies the number of spectral temperature averaging.