Standard for Sound Rating of Outdoor Unitary Equipment

ARI Standard 270-95: Standard for Sound Rating of Outdoor Unitary Equipment

For HVAC engineers, product designers, and specifiers, understanding and controlling acoustic performance is paramount. ARI Standard 270-95 provides an essential framework for objectively rating the sound generated by outdoor unitary equipment, ensuring consistency and comparability across manufacturers. This authoritative standard is a cornerstone for specifying and evaluating equipment where noise levels are a critical design consideration.

What is ARI Standard 270-95?

ARI Standard 270-95, developed by the Air-Conditioning and Refrigeration Institute (ARI), establishes the definitive procedures for testing and rating the sound output of outdoor unitary air-conditioning and heat pump equipment. Its primary purpose is to provide a standardized method for determining a single-number sound rating, allowing for clear comparisons and informed selection of equipment based on acoustic performance.

Scope & Purpose

This comprehensive standard governs the testing methodologies and rating requirements for the sound emitted by outdoor sections of factory-made unitary air-conditioning and heat pump equipment, as defined within ARI Standard 210/240-94. It specifies how to conduct acoustic tests, process the resulting data, and derive a published sound rating. The standard is specifically focused on sound power levels and does not extend to sound pressure levels at specific locations or installation-related acoustic mitigation strategies.

Who Must Comply?

• • Primary audience: HVAC Engineers, Acoustical Engineers, Product Engineers, Test Technicians, Installers, and Specifiers.
• • Industries affected: HVAC Manufacturing, Building Construction, Commercial Real Estate, and any sector utilizing unitary outdoor equipment.
• • Compliance nature: Voluntary, as indicated in Section 7 of the standard, though adherence is crucial for participation in ARI Certification Programs.
• • Enforcement: Compliance is typically verified through the ARI Certification Program, which involves independent testing and review.

Key Requirements Overview

• • The standard requires sound tests to be conducted in accordance with specific ANSI standards for sound power level determination.
• • Professionals must ensure that sound power levels are accurately measured across defined one-third octave bands.
• • Key provisions include procedures for adjusting sound power data to account for discrete frequency responses, reflecting how humans perceive tonal noise.
• • The standard mandates the calculation of a single-number sound rating based on these adjusted sound power levels, typically using A-weighting.
• • Marking and nameplate data requirements are outlined to clearly communicate the sound rating to users.

Related Standards & References

ARI Standard 270-95 often works in conjunction with other proven industry documents. It references ANSI Standard S12.32-1990 for the fundamental procedures of sound power level determination. Additionally, understanding the equipment itself is guided by ARI Standard 210/240-94 (now superseded by later versions), which defines unitary air-conditioning and heat pump equipment. While this standard is superseded, its principles and methodologies laid the groundwork for subsequent acoustic rating standards in the HVAC industry.