ISO 11042-1:1996

ISO 11042-1:1996 - Overview

ISO 11042-1:1996, "Gas turbines - Exhaust gas emission - Part 1: Measurement and evaluation", defines methods for measuring and evaluating exhaust gas emissions from gas turbines (excluding aircraft applications). The standard establishes common emission terms, test-environment and instrumentation requirements, data quality criteria, and procedures for correcting and converting measurement results so emissions can be judged uniformly (e.g., for acceptance testing or regulatory compliance).

Key topics and technical requirements

• Measured constituents: Guidance is provided for NOx (total NOx as NO2), CO, CO2, SOx (calculated from fuel sulfur when appropriate), unburned/partially burned hydrocarbons (UHC / VOCs), ammonia (NH3), oxygen (O2), smoke (Bacharach number), and solid particles.
• Sampling and sampling points: Selection of representative sampling planes and probe design (multihole averaging probes recommended) to ensure representative continuous-flow samples of exhaust ducts, chimneys or post‑treatment systems.
• Instrumentation specifications: Dedicated sections set out requirements for types of analyzers and performance expectations for NOx, CO/CO2, SOx, UHC/VOC, NH3, O2, smoke and particle analyzers, plus data acquisition systems.
• Quality of measurement and calibration: Definitions and requirements for accuracy, repeatability, resolution, response, stability and zero drift. Methods for instrument calibration and use of high‑accuracy calibration gas mixtures are referenced.
• Data correction and conversion: Procedures to convert between wet and dry exhaust gas, normalize results to a reference oxygen concentration (15% O2 is used as a typical reference), express emissions as mass flows related to dry exhaust volume at normal conditions, or relate emissions to power output or fuel energy.
• Test reporting and evaluation: Requirements for documenting turbine and fuel details, operating conditions, auxiliary equipment (e.g., selective catalytic reduction, recuperators), and presenting evaluated results. Informative annexes provide example test results, constituent information and physical properties.

Applications and users

ISO 11042-1 is intended for:

• Gas turbine manufacturers and test laboratories performing acceptance and commissioning tests
• Plant operators and engineering consultants conducting performance and emissions assessments
• Environmental compliance teams and regulators assessing exhaust emissions (excluding aircraft engines)
• Instrumentation vendors and system integrators designing monitoring and data acquisition systems

Practical uses include acceptance testing, performance verification, emissions reporting, and defining measurement protocols for installations with heat recovery, post‑combustion systems or emission controls.

Related standards

• ISO 11042-2: Automated emission monitoring (companion part)
• ISO 2314:1989 (Gas turbines - Acceptance tests)
• ISO 6141:1984 (Gas analysis - Calibration gas mixtures)
• ISO 5063:1978 and ISO 2533:1975 (referenced for specific methods and reference atmospheres)

Keywords: ISO 11042-1:1996, gas turbines, exhaust gas emission measurement, NOx, CO, SOx, UHC, emission monitoring, sampling probe, calibration, emissions evaluation.