STANDARD for SOUND RATING OF NON-DUCTED INDOOR AIR-CONDITIONING EQUIPMENT

ARI Standard 350: STANDARD for SOUND RATING OF NON-DUCTED INDOOR AIR-CONDITIONING EQUIPMENT

For professional engineers and designers involved in HVAC systems, understanding the acoustic performance of equipment is paramount to ensuring occupant comfort and meeting regulatory requirements. ARI Standard 350 provides an essential framework for objectively quantifying and communicating the sound emitted by non-ducted indoor air-conditioning units, enabling informed product selection and design decisions.

What is ARI Standard 350?

ARI Standard 350, developed by the Air-Conditioning and Refrigeration Institute (ARI), establishes a comprehensive methodology for determining the sound ratings of indoor components of non-ducted air-conditioning systems. Its primary purpose is to provide a standardized approach for measuring and reporting sound power levels, facilitating consistent comparison and evaluation of equipment acoustic performance across manufacturers.

Scope & Purpose

This standard specifically governs the sound testing and rating procedures for the indoor units of factory-made, non-ducted air-conditioning equipment, as detailed in related ARI standards. It outlines the precise methods for calculating sound power levels, including octave band sound power levels, A-weighted sound power levels, and tone-adjusted A-weighted sound power levels. The standard's scope does not extend to ducted systems or outdoor units.

Who Must Comply?

• • Primary audience: Acoustic Engineers, HVAC Engineers, Product Design Engineers, Test Technicians, and Quality Assurance Managers.
• • Industries affected: HVAC Manufacturing, Building Construction, Environmental Acoustics, and Product Testing Laboratories.
• • Compliance nature: While the standard itself may have been voluntary for publication at the time of its release, compliance with its methodologies is crucial for manufacturers seeking to provide credible and comparable sound ratings to their customers.
• • Enforcement: Compliance is typically self-enforced by manufacturers through adherence to the standard for published ratings. Third-party testing laboratories may also enforce these methods when commissioned.

Key Requirements Overview

• • The standard requires that sound tests be conducted using a standardized comparison method and a calibrated Reference Sound Source, in accordance with established ANSI and ARI test procedures.
• • Professionals must ensure that sound power levels are determined across a defined range of one-third octave bands, typically from 100 Hz to 10,000 Hz.
• • Key provisions include the calculation of an A-weighted sound power level to approximate human perception of loudness and a tone-adjusted A-weighted sound power level to account for the subjective impact of pure tones.
• • The standard mandates the minimum data that must be published to accompany these sound ratings, ensuring transparency and comparability for end-users.
• • It provides clear definitions for acoustical terms and specifies conformance conditions under which tests must be performed.

Related Standards & References

ARI Standard 350-2000 often works in conjunction with other industry documents. Complementary standards include:

• • ANSI S1.4A: For A-weighting adjustments applied to sound measurements.
• • ANSI S1.11: Defines the octave and one-third octave bands used for frequency analysis.
• • ARI Standard 250: Specifies the calibration requirements for the Reference Sound Source used in testing.
• • **ARI Standards 210/240, 340/360