R
EFERENCE
C
ONDITIONS
The displayed measuring results for concentration are normalized to a
reference temperature of 0°C (+32°F) and to an atmospheric pressure of
1013 mbar (14.69 psi) by factory setting. Other reference temperatures
and -pressures may be preset in the factory. The actual atmospheric
pressure on site is being be measured in
2240 PROcheck
and used for
normalization of the measured values. The sample gas inside the
measuring chamber is being kept at a constant temperature of 50°C
(122°F), so that in a normal case the influence of the measuring gas
temperature may be neglected.
M
EASURING
C
YCLE
During every measurement the standard measuring program will run
trough the following cycle:
1.
The sensor is being flushed with actual measuring gas (
P
).
2.
Then the instrument goes on hold for a short moment (
W
).
3.
Now the measurement is carried out. The result of the measurement
will be a mean value being formed from quite a number of single
measurements (
M
).
4.
The measurement result is being compared with the preset alarm
threshold values and if it falls short of the alarm limits as well as
remains within the time frame allowed for evaluation, a
corresponding signal is transmitted via signal line MOK(1..3)H or
MOK(1..3)V (closing respectively opening of a contact) through
the standard machine-interface (see
Annex A, fig. A2
).
The evaluation allowance, i.e. time span during which the result
must steadily remain below the alarm threshold value until a
MOK(1..3)-V or -H-signal will be released is 2 measuring cycles.
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