ISO 8178-3:2019

Overview

ISO 8178-3:2019 defines the standardized method for measuring exhaust gas smoke from compression-ignition reciprocating internal combustion engines (RIC) using a filter-type smoke meter (FSN). The standard applies to steady‑state engine operation and evaluates soot content by measuring the blackening of a filter (Filter Smoke Number, FSN) and converting FSN to black carbon mass concentration (mg/m3) where required. ISO 8178-3:2019 is intended for mobile, transportable and stationary non‑road engines (e.g., earth‑moving machines, generator sets) and excludes on‑road passenger and goods transport engines.

Key topics and technical requirements

• Measurement principle: a defined volume of exhaust is drawn through a clean filter; the degree of blackening (optical reflectance) is used to calculate FSN.
• FSN to mass conversion: correlation formulae in Annex C convert FSN to black carbon (BC) mass concentration; Annex D compares results from different instruments.
• Reference conditions: results are referenced to 25 °C (298 K) and 100 kPa; FSN is reported corresponding to an effective suction length (standardized to 405 mm where applicable).
• Apparatus and installation: measuring equipment must comply with ISO 10054; probe placement must ensure representative sampling and be upstream of any injected after‑treatment reagent or water.
• Sampling conditions: exhaust sample temperature must be above dew point; effective filtered column length and homogeneous flow through the filter are required.
• Operational constraints: testing requires steady‑state engine conditions (stable load, speed, exhaust temperature); fuel type can affect sensitivity and must be noted.
• Reporting: Annex A provides a standardized emission test report template for FSN test data.

Practical applications and users

ISO 8178-3:2019 is used by:

• Engine manufacturers and OEMs for design verification and emission characterization of non‑road compression‑ignition engines.
• Test laboratories conducting steady‑state smoke tests with filter‑type smoke meters.
• Regulators and certification bodies for emission monitoring and compliance assessments where FSN‑based methods are specified.
• Environmental and maintenance engineers assessing soot/black carbon emissions from stationary and mobile non‑road machinery.

Benefits include reproducible smoke measurements, standardized reporting, and conversion of visual smoke metrics (FSN) into mass‑based BC concentrations for comparison and regulatory use.

Related standards

• ISO 10054 - specifies characteristics of filter‑type smoke meters (instrument requirements).
• ISO 8178‑1 / ISO 8178 series - broader framework for exhaust emission measurement and particulate methods.
• ISO 8178‑9 - covers opacimeter/opacity methods (opacimeter removed from this part).
• ISO 9096 - related particulate measurement methods (see annexes for cross‑references).

Keywords: ISO 8178-3:2019, filter-type smoke meter, FSN, black carbon, soot measurement, reciprocating internal combustion engines, exhaust emission measurement, compression ignition, non‑road engines.