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ISO 29042-8:2011 — Safety of Machinery — Room Method for Pollutant Concentration Parameter
Evaluating Machine Airborne Emissions Using a Controlled Test Room Environment
Introduction
ISO 29042-8:2011, developed by ISO/TC 199, specifies a room method for measuring the pollutant concentration parameter (Pcr) of airborne hazardous substances from machines. This method applies to machines with local exhaust ventilation (air flow rate ≤ 500 m³/h) and machines without recirculated air, operating under defined conditions in a test room.
The room method complements the test bench method of ISO 29042-7 by accommodating machines that cannot be placed in a test bench or require their own ventilation systems.
Test Room Requirements and Measurement Configuration
The test room must meet strict criteria: no other source of the given pollutant, minimum volume of 200 m³, distances greater than 2 m between the machine and walls/ceiling, and no return air from local exhaust ventilation. At least four measurement points around the machine are required, positioned using empirical techniques to capture major emission areas.
| Parameter | Requirement | Purpose |
|---|---|---|
| Room volume | ≥ 200 m³ | Sufficient dilution and dispersion |
| Measurement points | ≥ 4 around machine | Capture spatial concentration variation |
| Machine-wall distance | > 2 m | Prevent boundary effects |
| Local exhaust flow | ≤ 500 m³/h | Scope limitation of the standard |
| Tests per point | ≥ 3 measurements | Statistical reliability |
Engineering Design Insights
Measurement Procedure and Machine Operation
The machine is operated according to its intended use, with working procedures, tools, and materials specified in Type-C standards. The measurement time must be sufficient for representative concentration data during normal operational cycles. The machine should be started and reach normal working conditions before measurement instruments are activated. However, attention must be paid to unusually high emissions that can occur during start-up. The exact timing or number of cycles should be specified in Type-C standards.
Data Analysis and Expression of Results
For each sequential test, the mean value and standard deviation across all measurement points are calculated. The overall mean and one-sided 95% confidence interval are then computed per ISO 2602. The pollutant concentration parameter of the room, Pcr, is the sum of the mean value and the one-sided 95% confidence interval. This approach provides a conservative estimate suitable for safety assessments.
Proper supply air design is critical to avoid cross-draughts in the measurement zone. Airflow from all measurement points must be directed toward the local exhaust ventilation, which should be verified using smoke cartridges before testing.
Comparison with Test Bench Method (ISO 29042-7)
While ISO 29042-7 uses a test cabin for direct capture, ISO 29042-8 uses a room environment with local exhaust ventilation. The room method is better suited for larger machines or those with integrated exhaust systems. Both methods produce a pollutant concentration parameter, but the room method also provides a standard deviation value that indicates the dispersion of the emitted pollutant in the room.
FAQs
Q1: When should the room method be used instead of the test bench method?
A: The room method is appropriate for machines with local exhaust ventilation (≤ 500 m³/h) and machines without recirculated air that cannot be accommodated in a standard test bench.
A: The room method is appropriate for machines with local exhaust ventilation (≤ 500 m³/h) and machines without recirculated air that cannot be accommodated in a standard test bench.
Q2: Why is a minimum room volume of 200 m³ required?
A: This volume ensures adequate dilution of pollutants and minimizes wall effects on airflow patterns, providing a realistic environment for emission measurement.
A: This volume ensures adequate dilution of pollutants and minimizes wall effects on airflow patterns, providing a realistic environment for emission measurement.
Q3: How are measurement points determined?
A: At least four points are selected around the machine using empirical techniques to identify major emission areas. Exact positions are specified in Type-C standards where available.
A: At least four points are selected around the machine using empirical techniques to identify major emission areas. Exact positions are specified in Type-C standards where available.
Q4: Can start-up emissions be captured?
A: Yes, but careful timing is needed. The method requires the machine to reach normal working conditions before measurement, while also noting that unusually high emissions during start-up should not be overlooked.
A: Yes, but careful timing is needed. The method requires the machine to reach normal working conditions before measurement, while also noting that unusually high emissions during start-up should not be overlooked.
