ANSI/ASHRAE Standard 120-2017 Edition

ANSI/ASHRAE Standard 120-2017 Edition Method of Testing to Determine Flow Resistance of HVAC Ducts and Fittings establishes uniform methods of laboratory testingn of HVAC ducts and fittings to determine their resistance to airflow.

First published in 1999, ASHRAE Standard 120 establishes uniform methods of laboratory testing of HVAC ducts and fittings to determine their resistance to airflow. The fitting losses, which reported as local loss coefficients, are  to update and refine the ASHRAE Duct Fitting Database. To date, at least eight research projects have used the test methods of Standard 120 to improve this database. The significant change to this edition of the standard is that the length upstream of the test duct or fitting increased from 10 to 15 hydraulic diameters

You can also Read ANSI/ASHRAE Standard 52.2-2017 Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size

ANSI/ASHRAE Standard 120-2017 Edition Content

• Purpose
• Scope
• Definitions, Symbols, and Subscripts
• Compliance Requirements
• Applicability
• Instrumentation
• Flow Measuring Systems and Test Setups
• Observations and Conduct of Test
• Calculations
• Test Results and Report
• References
• A—Time-Weighted Average
• B—Leakage Measurement
• C—Flexible Duct Test Setup Guide
• D—Example Test Systems

ANSI/ASHRAE Standard 120-2017 Edition Scope

• This standard  used to determine the change in total pressure resulting from airflow in HVAC ducts and fittings.
• The test results used to determine duct flow losses in pressure loss per unit length. Fitting losses  reported as local loss coefficients.
• This standard does not cover interpretation of test data.

ANSI/ASHRAE Standard 120-2017 Edition DEFINITIONS, SYMBOLS, AND SUBSCRIPTS

• Accuracy: the degree of conformity of an indicated value to an accepted standard value or true value. The degree of inaccuracy known as “total measurement error” and is the sum of bias error and also precision error.
• Bias error (systematic error): the difference between the true or actual value  measured and the indicated value from the measuring system that persists and is usually due to the particular instrument or technique of measurement. These errors can be corrected through calibration.
• Confidence level: the probability that a stated interval will include the true value. In analyzing experimental data, a level of 95% is usually used.
• Duct, flexible: any duct constructed of flexible materials, such as polymeric films, metal foils, and also impregnated fabrics.
• Duct, rigid: any duct constructed of rigid materials, such as metal and also fiberglass duct board.

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ANSI/ASHRAE Standard 120-2017 Edition

ANSI/ASHRAE Standard 120-2017 Edition