ISO 16247:2004

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.