Adjusting the PMT on 42iQ NO-NO2-NOx Analyzer using Auto-Calibration

The 42iQ gas analyzer offers a unique new feature for automatically adjusting the Photo Multiplier Tube (PMT) gain. Adjusting the PMT allows the user to reset the analyzer back to factory specifications and improve analyzer response. Before beginning this procedure, the user should have a calibration system set up that is capable of generating NO_x-free zero-air, and a NO_x span concentration at approximately 90% of the analyzer range. For example, if the operating range of the analyzer is 200 ppb, the PMT adjustment should be performed while sampling gas that is at 180 ppb.

Begin by sampling NO_x-free zero-air for 10-15 minutes, or until the NO/NO_x readings are stable. Perform a zero calibration on the 42iQ:

Calibration>Calibrate Backgrounds>Calibrate NO Background

Press Calibrate to set the NO reading to zero and save the new background

Calibration>Calibrate Backgrounds>Calibrate NO_x Background

Press Calibrate to set the NO_x reading to zero and save the new background.

Next, navigate to the Home Screen>Calibration>Advanced Calibration>Manual

Calibration>Adjust Span Coefficients> screen and reset the NO and NO_x Span Coefficients to 1.000.

Next, generate the 90% NO_x span gas with the calibration system and allow the 42iQ to sample the gas for 10-15 minutes or until the NO/NO_x readings are stable. Navigate to the following screen:

In the “Target Concentration” field, enter the concentration of the NO_x span gas that is being sampled at 180 ppb by the 42iQ.  Press the Start button after the “Auto Calibration” field and wait approximately 5 minutes until the calibration is complete. The PMT will now be optimized for your particular instrument!

 42iQ Instrument Manual