STANDARD for PERFORMANCE AND CALIBRATION OF REFERENCE SOUND SOURCES

ARI Standard 250: STANDARD for PERFORMANCE AND CALIBRATION OF REFERENCE SOUND SOURCES

Ensuring accurate and repeatable acoustic measurements is fundamental to product development and certification in the HVAC industry. ARI Standard 250 provides the essential framework for defining and calibrating the performance of reference sound sources (RSS), acting as a cornerstone for reliable sound power level determinations. This authoritative standard is crucial for engineers and manufacturers aiming to meet stringent acoustic performance criteria.

What is ARI Standard 250?

ARI Standard 250, developed by the Air-Conditioning and Refrigeration Institute (ARI), establishes the performance characteristics and defines the acoustical calibration procedures for reference sound sources. Its primary purpose is to ensure that these reference sources, vital for acoustic testing, are stable, predictable, and transferable in their sound output, thereby guaranteeing the consistency of sound power level measurements across different testing environments and equipment.

Scope & Purpose

This standard specifically governs the performance requirements, calibration procedures, and transfer of calibration for reference sound sources used in conjunction with ARI sound rating standards. It covers a broad frequency range, typically from 50 Hz to 10,000 Hz, within one-third octave bands. The scope explicitly defines how to calibrate primary and secondary reference sound sources and outlines the data required for published information, ensuring a comprehensive approach to acoustic metrology.

Who Must Comply?

• • Primary audience: Acoustical Engineers, Test Engineers, HVAC Engineers, Product Development Engineers, and Calibration Technicians.
• • Industries affected: HVAC manufacturing, acoustics consulting, product certification bodies, and manufacturers of acoustic measurement equipment.
• • Compliance nature: While ARI standards are often voluntary, compliance is highly recommended for companies seeking to demonstrate adherence to industry best practices and ensure the credibility of their acoustic testing data.
• • Enforcement: Compliance is typically self-enforced by manufacturers and testing laboratories, often verified through independent product certification or audits.

Key Requirements Overview

The standard mandates several critical aspects for reference sound sources:

• • Performance Characteristics: Professionals must ensure that reference sound sources exhibit stable, broad-band sound power output without prominent tones within the specified frequency range.
• • Calibration Procedures: ARI Standard 250 outlines distinct procedures for calibrating primary and secondary reference sound sources, ensuring traceability and accuracy.
• • Sound Power Level Limits: The standard defines acceptable spreads and tolerances for one-third octave band sound power levels to ensure consistency and repeatability.
• • Physical Dimensions & Isolation: Requirements are specified for the physical size of the sound source and the necessity of integral vibration isolation to prevent external vibrations from affecting measurements.
• • Recalibration Schedule: Provisions are included for regular recalibration to maintain the accuracy and reliability of the reference sound source over its operational lifespan.

Related Standards & References

ARI Standard 250 often works in conjunction with other foundational acoustic standards. Complementary documents may include ANSI/ASA S12.5, which defines the methods for determining the sound power levels of noise sources, and ASHRAE Terminology of Heating, Ventilation, Air Conditioning and Refrigeration, for standardized definitions. These references collectively provide a comprehensive ecosystem for acoustic testing and product rating.