Model NGA2000 NDIR
Instruction Manual
The modulation check is a measure of the energy absorption capacity of a gas mixture, where total absorbency is 100% modulation and zero absorbency is 0% modulation. The modulation check can be used as a tool for tracking the sensitivity of the Analyzer Module and for discovering potential detector/source problems.
To perform a modulation check, do the following:
Access the Primary Variable Parameters menu.
Select Modulation Check.
Follow the Instructions and Then line commands, which are the following:
Flow zero gas, press START softkey and wait.
Flow span gas when prompted, press START softkey and wait.
When the Instructions line again prompts the user to flow zero gas, the modulation check is finished.
Note the value on the Percent Modulation line.
Find the Percent Modulation value on the Data Sheet in the rear of this manual. Some standard Analyzer Modules will not have a value. If a value is present, compare this to the new value.
If 100% span gas was used during the modulation check, the new value should be within ±10% of value on the Data Sheet. If it is out of this range, call the factory for further interpretation. If modulation checks are used for trending, variance from check to check should not exceed ±20% per month.
Rosemount Analytical Inc. A Division of Emerson Process Management | Maintenance and Troubleshooting |