If the deviation of the two values is less then the allowed maximum calibration deviation (see menu "Tolerances", p. 5-7/8), the calibration may start. If not, the stability control is starting again until a stable measurement is possible. The time in the line "Procedure times-out after" is the limit for the whole procedure.

The following figure shows the procedure of the stability controlled zero and span gas calibration:

Concentration

Start Span

Calibration

Averaging

over Ti

Ti

Start Zero

Calibration

Purge

Stability

Stability

Stability

Stability

Time

Time

Time

Time

Time

Time

 

Note:

The stability time and the averaging time are factory settings and cannot be changed by the customer. If you want to use other values, ask your service !

Line of variables "Analog output during calibration":

Here, you can determine if you want to hold the analog output and the limits of a local SIO in the MLT analyzer module during calibration. The set-ups for a platform or MLT analyzer SIO have to be done in the menu "Analog Outputs" (see 5.2.1 p. 5-87).

♦Tracking: The analog output signal is following to the signal during the whole calibra- tion procedure.

♦Holding: During the whole calibration procedure the analog output signal is fixed to the last signal before calibration. This adjustment may be used for instance to control limits with the analog output.

Sample Gas

Zeroing

Spanning

Sample Gas

Analog Output

 

 

 

Tracking

 

 

xV

0V

 

 

Analog Output

 

 

 

Holding

 

 

 

5 - 10

NGA 2000

90003482(2) [NGA-e (MLT-Software 3.2.X)] 07/98