Emerson NGA2000 TO2 Startup Procedure, Quick Start Feature, GAS Scale Factor GSF, Calibration

Model NGA2000 TO2

Instruction Manual

748374-F March 2003

3-3 STARTUP PROCEDURE

Establish sample or zero gas flow through the analyzer module at a nominal flow rate of 2 SCFH (1 l/min). Allow gas to flow for 15 to 30 seconds before applying power. Apply power to the TO2 Analyzer Module.

Upon initial startup, the separate modules, Con- troller Board and network "self-install." The dis- play shows the progress of the automatic installation routine, together with a button marked RE_INIT. If the initialization hangs up, pressing the RE_INIT button will restart it, but will cause all the binding information to be erased. The Display will then appear as above. For details on binding, please consult the Plat- form instruction manual.

Establish that sample flow rate is within specifi- cations (see Section 1-5 SPECIFICATIONS on page 1-4). Input security codes (see NGA Ref- erence manual), calibrate, and begin routine operation as following subsections indicate.

difference, the diffusion change can be com- pensated in software. The GSF can be entered manually or calculated automatically. Calcula- tion of the GSF requires the user to enter the sample gas composition. In most applications, the GSF is not required. However, some back- grounds exhibit significantly different diffusion characteristics versus nitrogen (such as helium or hydrogen) and the GSF may improve per- formance.

Under the Technical Level Configuration sub- menu, select Diagnostic menus... and then se- lect Analyzer Module Diagnostics…. In the Analyzer Module Diagnostics sub-menu select Calibration Parameters.... In the Ad- vanced/Expert Calibration sub-menu select Gas Scale Factor.... To use the GSF, enter the volumetric percentages of each component pre- sent in the sample gas. To view more back- ground components, press the MORE softkey. The total must add up to 100 or a new factor will not be computed. If you have a background component which is not shown in this menu, please consult the factory for assistance.

3-4 QUICK START FEATURE

This analyzer module is equipped with a quick start feature which allows the sensor to begin measuring low ppm oxygen faster. This feature can be used when the analyzer is first turned on to decrease the time required for the sensor to reach equilibrium. This function is most effec- tive for gas sample measurements below 100 ppm. To maintain sensor life, it is recom- mended that this feature be used no more than two times in any 24 hour period.

Under the Basic Controls sub-menu, move the cursor to Initiate quick start! and press the ↵ key. The unit will begin the quick start function immediately. This procedure will last for ap- proximately 45 seconds. The last measured value is held for the duration of the procedure to prevent false reading fluctuations.

3-5 GAS SCALE FACTOR (GSF)

The Gas Scale Factor is used to correct for background gases other than nitrogen. When the background of the sample is other than ni- trogen, the diffusion rate of oxygen into the sen- sor changes. By correcting for the background

Once you have entered all the background composition information, move the cursor to Compute new adjusted gas scale factor! and press the ↵ key and the analyzer module will automatically calculate the new gas scale factor.

3-6 CALIBRATION

The TO2 analyzer module is fully factory cali- brated using certified gas standards prior to shipment. If the analyzer is operated within its specified operating conditions, no calibration is required. The zero calibration is very stable and does not require checking more than once a year. Depending upon the nature of your appli- cation, it may be beneficial to verify the span calibration of the analyzer module every 3-4 months. The following procedure illustrates how to initiate a zero/span calibration.

Under the Expert Controls sub-menu select Ex- pert Analyzer Controls and Measurement…, set the Range Number to the range that will be used during sample analysis. Return to the Main Menu by pressing the HOME softkey.

Rosemount Analytical Inc. A Division of Emerson Process Management Startup and Operation 3-3