Overview
ISO 16247:2004 - "Road vehicles - Detection of exhaust system leaks - Helium test method and detection device specification" defines a tracer-gas (helium) test procedure and equipment requirements to detect and localize leaks in road-vehicle exhaust systems. The standard is intended to improve the quality and reproducibility of exhaust gas measurements used in emissions testing and diagnosis, and is applicable in automotive workshops, end-of-line production, laboratories before emission tests, and vehicle testing/diagnosis stations.
Key topics and technical requirements
- Two-step test method
- Step 1 (engine stopped): auditive detection with exhaust pressurization to reveal large leaks (preparation for Step 2).
- Step 2 (engine idling): helium tracer-gas injection and detection to locate small leaks (down to 0.1 mm under optimal conditions).
- Pressurization equipment
- Supply of clean, dry, oil-free compressed air, adjustable regulator (limit ~40 kPa / 0.4 bar) and manometer.
- Flexible leak-proof connection and outlet plugs for multi‑outlet systems.
- Helium tracer and injection
- Industrial helium cylinder with flow-rate control; injection at the engine air intake to achieve a target helium concentration (calibrated at 20 000 µl/l).
- Restriction and calibration device
- Creates a small positive back-pressure (~3 kPa / 0.03 bar) and includes a 1 mm calibrated hole for device calibration and reference.
- Detection device specifications
- Materials resistant to corrosion and non-adsorbing to helium; sampling probe able to withstand ~200 °C and provide full access around the exhaust.
- Sampling line length ≥ 6 m; filtered sampled flow; operator warning for insufficient sample flow.
- Sensitivity only to helium, detection time ≤ 5 s, and ability to detect a 1 mm calibrated leak with engine idle at 20 000 µl/l helium.
- Calibration curve defined with calibrated leak holes (0.1, 0.2, 0.5, 0.8, 1.0 mm).
Applications and users
ISO 16247 is practical for:
- Automotive service and repair workshops performing emission diagnostics and repairs.
- OEM end-of-line testing for vehicles and exhaust components.
- Test laboratories preparing vehicles for formal exhaust-emission tests.
- Inspection, maintenance, and vehicle diagnostic stations validating exhaust system integrity.
Benefits include improved accuracy of emissions measurements, standardized leak localization, and reduced false readings from exhaust leaks.
Related standards
- ISO 3929 - Measurement methods for exhaust gas emissions during inspection or maintenance (complementary)
- ISO 13556 - Localization of exhaust system leaks and equipment specifications (related detection limits)
- ISO 31 series (quantities and units) - referenced for unit conventions
Keywords: ISO 16247, helium test method, exhaust system leaks, leak detection, helium detector, vehicle emissions testing, tracer gas, exhaust leak localization.
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