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ISO 29042-7:2010 — Safety of Machinery — Pollutant Concentration Parameter (Test Bench Method)
Understanding the Test Bench Method for Measuring Airborne Pollutant Concentration from Machinery
Introduction
ISO 29042-7:2010 is a Type-B standard under the ISO 12100 machinery safety framework, developed by ISO/TC 199. It specifies a test bench method for measuring the pollutant concentration parameter (Pcc) of a given airborne hazardous substance emitted from a machine. This parameter quantifies the concentration of gases, vapours, or respirable particles near the machine operating under defined conditions.
The pollutant concentration parameter Pcc serves as a key metric for evaluating machine emission performance, comparing machines within the same group, and determining the state of the art for a machine category with respect to emission control.
Test Bench Configuration and Measurement Principles
The test bench consists of a test cabin with a funnel and an air mover that generates airflow from the inlet toward the funnel. A permeable inlet (macroporous filter or perforated plate) ensures uniform airflow and prevents pollutant escape. The cabin cross-section must be at least five times the maximum cross-sectional area of the machine under test.
| Parameter | Requirement | Remarks |
|---|---|---|
| Cabin cross-section (Ac) | ≥ 5 × machine cross-section | Ensures uniform flow |
| Measurement plane | Plane 1 in exhaust duct (preferred); Plane 2 near funnel middle axis (alternative) | Plane 2 used for larger sampling heads |
| Exhaust flow rate | Constant, specified in Type-C standards | Must be controlled |
| Minimum tests | At least 3 tests | Per ISO 2602 statistical requirements |
| Measurement time | Sufficient for representative data | Based on operational cycles |
The preferred measurement location is Plane 1 in the exhaust duct. If instruments require lower air velocities or have larger sampling heads, Plane 2 in the funnel middle axis near the exhaust duct may be used as an alternative.
Engineering Design Insights for Pollutant Measurement
Machine Positioning and Operation
The machine is positioned with its emission source along the test cabin longitudinal axis at specified distances l1 (from funnel start) and l0 (from inlet). The machine must be operated according to its intended use, with working procedures, tools, and materials defined by relevant Type-C standards. If the machine has a built-in separator recirculating air toward the working zone, the separator outlet must be located within the test cabin so that secondary pollutant sources reach the measurement plane.
Measurement Procedures and Data Expression
Measurement procedures must comply with appropriate International Standards for pollutant concentration determination. The measurement must account for normal operational cycles, with sampling duration sufficient for representative concentration data. The final pollutant concentration parameter Pcc is expressed as the sum of the mean value and the 95% confidence interval according to ISO 2602. This statistical approach accounts for inherent variability in emission measurements.
Tests shall not be carried out unless manufacturer’s specifications for operating the pollutant control system are available. If the machine is equipped with a pollutant control system, it must be adjusted per manufacturer instructions.
Practical Applications in Machine Safety Evaluation
The Pcc parameter enables five distinct use cases: (a) evaluating machine performance, (b) assessing design improvements, (c) comparing machines across different groups with similar intended use, (d) ranking machines within the same group, and (e) establishing the state of the art for emission control in a machine category. This standardized approach ensures consistent, comparable results across laboratories and testing scenarios.
FAQs
Q1: What types of pollutants can be measured with ISO 29042-7?
A: The method is applicable to gases, vapours, and respirable particles. It is not intended for non-respirable particulate matter or liquid aerosols outside the specified scope.
A: The method is applicable to gases, vapours, and respirable particles. It is not intended for non-respirable particulate matter or liquid aerosols outside the specified scope.
Q2: How does the test cabin size affect measurements?
A: The test cabin must provide uniform airflow and prevent pollutant escape. The machine cross-section cannot exceed one-fifth of the cabin cross-section, ensuring that emission sources are adequately surrounded by the capture airflow.
A: The test cabin must provide uniform airflow and prevent pollutant escape. The machine cross-section cannot exceed one-fifth of the cabin cross-section, ensuring that emission sources are adequately surrounded by the capture airflow.
Q3: Why is the confidence interval included in Pcc?
A: The 95% confidence interval accounts for statistical variability across repeated tests, providing a reliable upper-bound estimate of the pollutant concentration parameter for safety assessment purposes.
A: The 95% confidence interval accounts for statistical variability across repeated tests, providing a reliable upper-bound estimate of the pollutant concentration parameter for safety assessment purposes.
Q4: Can this method be used for field measurements?
A: No, this part specifically describes a test bench method. For field or room-based measurements, refer to ISO 29042-8 (room method) or ISO 29042-9 (decontamination index).
A: No, this part specifically describes a test bench method. For field or room-based measurements, refer to ISO 29042-8 (room method) or ISO 29042-9 (decontamination index).
