EN 27574-4:1988 PDF

Overview

EN 27574-4:1988 (ISO 7574-4:1985) - published by CEN/ISO - defines statistical methods to determine and verify a labelled noise emission value for batches (lots) of machinery and equipment. It gives labellers guidelines to set a stated (labelled) upper noise value and specifies sampling procedures to check whether a lot complies with that value. The standard assumes noise emission values in a batch are approximately normally distributed and requires a specified reference standard deviation for verification. It does not cover the consequences or corrective actions if a lot fails verification.

Key topics and requirements

• Purpose: Determine and verify a labelled (upper) noise emission value for batches of machines.
• Assumptions: Noise values ≈ normal distribution; verification uses a reference standard deviation (σM).
• Risk/acceptance basis: Procedures are designed so that a lot with at most 6.5% of items exceeding the labelled value has approximately 95% probability of acceptance (producer’s risk point).
• Labelled-value guidance: Labellers are given formulae to set the labelled value (Lc) relative to measured mean and σM (examples and equations provided in the standard).
• Sampling procedures: Three equivalent inspection methods are specified - single sampling, double sampling, and sequential sampling - each requiring a prescribed sample size and accept/reject criteria (using operating-characteristic concepts).
• Reference information: Annexes include operating-characteristic curves, examples and guidance for estimating standard deviations and using OC curves.
• Scope limits: Focuses on checking an upper limit only (one-sided). It does not prescribe actions after non-conformance.

Practical applications and users

Who uses this standard:

• Manufacturers and labellers of mass-produced machinery and equipment who must declare noise emission values on labels or in documentation.
• Testing laboratories and quality departments performing batch verification of noise emissions.
• Certification bodies and regulators designing labelling codes or verification procedures for specific machine families.

Practical uses:

• Setting a defensible, statistically based labelled noise limit for product families.
• Designing sampling plans to verify compliance of lots with declared noise values.
• Integrating verification rules into an organizational noise-labelling code (the code must specify σM, sampling method and sample sizes).

Related standards

• ISO 7574-1 (general considerations and definitions)
• ISO 3951 (sampling by variables - referenced procedure)
• ISO 4871 (noise labelling of machinery and equipment)
• EN 27574-4 is identical in content to ISO 7574-4:1985 and contains annexes with OC curves and symbol lists for practical implementation.

Keywords: acoustics standard, noise emission, machinery noise, statistical sampling, labelled value, batch verification, ISO 7574-4, EN 27574-4, sampling inspection, operating characteristic.