LumaSense Technologies INNOVA 1314i User Manual

Page 188

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Chapter 14

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BE6030-12

1314i Photoacoustic Gas Monitor

LumaSense Technologies A/S

Page 188 of 199

WET MEAS. < DRY MEAS. FOR WATER FILTER and

HUMIDITY INTERFERENCE FACTOR < 0

Both these messages are associated with a combined zero-point and

humidity-interference calibration task.

WET MEAS. < DRY MEAS. FOR WATER FILTER

HUMIDITY INTERFERENCE FACTOR < 0

During the zero-point calibration task the signal is measured when

dry, zero gas is in the cell – this is a measure of the noise in the cell

when a particular optical filter is used. This measurement allows the

concentration offset factor for the particular filter to be calculated.

During the humidity-interference calibration task the signal in the cell

when a particular optical filter is used is measured when wet, zero gas

is in the cell – this signal is compared with the signal measured with

the water-vapour filter to give the humidity gain factor. The above

message is given if the humidity gain factor is found to be less than

zero. This could indicate that the zero-gas you used during the zero-

point calibration was not dry, or alternatively that the concentration of

water-vapour you used during the humidity-interference calibration

was too low.

GAS X: CALIBRATION FACTOR LESS THAN 0

This message is associated with a single-point span calibration task.

The gas conversion factor calculated during the single-point span

calibration task is found to be less than zero. This could indicate that

the concentration of gas used during the calibration was too low.

GAS X: LOW MEAS. > HIGH MEAS.

GAS X: MEAS. INDICATES LINEAR COHERENCE

GAS X: MEAS. DOES NOT FIT NON-LINEAR CURVE

GAS X: CALIBRATION IMPOSSIBLE: MAX ITER.

All these messages are associated with a two-point span calibration

task.

During a two-point span calibration the signal (V

high

) is measured

when the gas concentration C

high

is in the cell, and the signal (V

low

) is

measured when the gas concentration C

low

is in the cell (see

section

12.9

).

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