8.3 Oxygen interference check
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - International Codes - NOx Technical Code (2008) - Technical Code on Control of Emission of Nitrogen Oxides from Marine Diesel Engines - Appendix 4 - Calibration of the analytical and measurement instruments - 8 Adjustment of the HFID - 8.3 Oxygen interference check

8.3 Oxygen interference check

  8.3.1 The oxygen interference check shall be determined when introducing an analyser into service and after major service intervals.

  8.3.2 A range shall be chosen where the oxygen interference check gases will fall in the upper 50%. The test shall be conducted with the oven temperature set as required. The oxygen interference gases are specified in 2.2.4.

  • .1 The analyser shall be zeroed.

  • .2 The analyser shall be spanned with the 21% oxygen blend.

  • .3 The zero response shall be rechecked. If it has changed more than 0.5% of full scale (FS) steps 8.3.2.1 and 8.3.2.2 shall be repeated.

  • .4 The 5% and 10% oxygen interference check gases shall be introduced.

  • .5 The zero response shall be rechecked. If it has changed more than ± 1% of full scale, the test shall be repeated.

  • .6 The oxygen interference (%O 2 I) shall be calculated for each mixture in step .4 as follows:

  • where: analyser response is (A/% FS at A) · (%FS at B)

  • where:

    • A = hydrocarbon concentration in ppmC (microlitres per litre) of the span gas used in 8.3.2.2

    • B = hydrocarbon concentration (ppmC) of the oxygen interference check gases used in 8.3.2.4

    • D = percentage of full scale analyser response due to A

  • .7 The % of oxygen interference (%O 2 I) shall be less than ± 3.0% for all required oxygen interference check gases prior to testing.

  • .8 If the oxygen interference is greater than ± 3.0%, the air flow above and below the manufacturer’s specifications shall be incrementally adjusted, repeating 8.1 for each flow.

  • .9 If the oxygen interference is greater than ± 3.0% after adjusting the air flow, the fuel flow, and thereafter the sample flow shall be varied, repeating 8.1 for each new setting.

  • .10 If the oxygen interference is still greater than ± 3.0%, the analyser, (H)FID fuel, or burner air shall be repaired or replaced prior to testing. This clause shall then be repeated with the repaired or replaced equipment or gases.

Parent topic: 8 Adjustment of the HFID
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