IDD Testing Standard

IDD® 2023-1 Intelligent Downstream Device Testing Standard

Test Method For Rating Intelligent Downstream Devices

ALPHA OMEGA LABS, INC., INC. INDUSTRIAL POLICY ON STANDARDS

Alpha Omega Labs, Inc., Inc. uses its best efforts to promulgate Standards and Guidelines for the benefit of the public considering available information and accepted industry practices. However, Alpha Omega Labs, Inc., Inc. does not guarantee, certify, or assure the safety or performance of any products, components, or systems tested, installed, or operated in accordance with Alpha Omega Labs, Inc., Inc. Standards or Guidelines or that any tests conducted under its Standards or Guidelines will be nonhazardous or free from risk.

CONTENTS

Foreword...........................................................................................................................................1

1 Purpose ........................................................................................................................................1

2 Scope ............................................................................................................................................2

3 Definitions................................................................................................................................... 2

4 Instrumentation......................................................................................................................... 3

5 Test Setup ....................................................................................................................................5

6 Test Methods………………………………………………………………………………………………………………….6

7 Test Report.................................................................................................................................. 6

8 References ................................................................................................................................. 8

Alpha Omega Labs, Inc., Inc. Test Standard IDD® – Intelligent Downstream Device version 1.01 2023

Method of Test for Validating Intelligent Downstream Devices with A High Turndown Commensurate to High Air Flow Accuracies

Foreword

Based on a new disruptive innovation of variable orifice plate technology offering next generation air flow measurement and control, an updated testing standard is required with cutting edge air flow measurement equipment to validate the performance. The Variable Orifice Plate Technology features turndowns of up to 100-1 and airflow accuracies to within a few Cubic Feet per Minute, making this technology a disruptive innovation. Therefore, a new standard is required to validate the performance of the Variable Orifice Plate technology.

An HVAC Consulting Engineer indicates performance requirements for airflow control for a given project. The requirements are specified in terms of nominal flow rates, accuracy, stability, operating pressures, and other relevant conditions. Contractors or suppliers document performance of proposed equipment based on tests run and reported in accordance with this standard. Commissioning Agents then balance the system. A supplier of variable orifice plate technology wishing to publish the capabilities of a product shall execute tests and reports results in accordance with this standard and receive an IDD® certification label.

1 Purpose

This standard specifies instrumentation, facilities, test installation methods, and procedures for determining and defining the requirements of IDD® certified devices to ensure the accuracy and stability, and high turndown performance that the IDD® Certification demands.

2 Scope

This standard applies to control systems integrated into devices using variable orifice technology used for pressure independent airflow control in terminal units for variable-air-volume (VAV) and constant volume (CV) air moving systems.

3 Definitions

3.1 This section provides definitions of key terms used in this standard. For terms not defined, refer to the definitions listed in ASHRAE Terminology of Heating, Ventilation, Air Conditioning, & Refrigeration.

air terminal: a single-duct air valve that automatically modulates the volume of air delivered to or removed from a defined space in response to an external demand.

airflow: for the purpose of this test method, airflow is the unit volume displacement of standard air per unit time. It is normally measured in standard cubic feet per minute (ft3/min) or liters per second (L/s).

differential pressure: difference in pressure between any two locations in a system.

equivalent diameter: the diameter of a circular-duct equivalent that will have a cross-sectional area that is equal to that of a particular rectangular duct. The equivalent diameter is calculated by the following equation: De = (4 × A/π )0.5, where A is the cross-sectional area.

national measurement standard: measurement standard recognized by national authority to serve in a state or economy as the basis for assigning quantity values to other measurement standards.

pressure: force exerted per unit area.

reference airflow measuring system: combination of sensing devices and data acquisition hardware and software that produces the airflow value against which the system under test (SUT) is compared.

shall: where shall and shall not are used for a specified provision, that provision is mandatory if compliance with this test method is claimed.

standard air: air that meets the following criteria:

• I-P units: dry air at 70°F and 14.696 psia. Under these conditions, dry air has a mass density of

0.075 lb/ft3. Note: this is not the same as SI standard air.

• SI units: dry air at 20°C and 101.325 kPa. Under these conditions, dry air has a mass density of 1.204 kg/m3. Note: this is not the same as I-P standard air.

system under test (SUT): the combination of hardware and software that operates as a system to control airflow rate to a given setpoint. This system will likely include an airflow sensor, a controller, a terminal unit, a damper, and a damper actuator.

test specifier: individual or organization that calls out details for a test conforming to this Method of Testing (MOT). The test specifier may designate products to be tested, airflow rates and pressure drops, ambient temperatures, calibration procedures, and pass/fail criteria.

tolerance: the level of accuracy desired in the airflow control SUT, the criterion by which the SUT is judged to pass or fail the steady-state accuracy test.

velocity pressure: in a moving fluid, the pressure due to the velocity and density of the fluid, expressed by the velocity squared times the fluid density, divided by two ( V2/2). For example, with standard air specific at 0.075 lbm/ft3 (1.204 kg/m3), Pv in inches of water (kPa) = (V/4005)2.

zero drift: change in sensor output at zero flow with the passage of time, change in temperature, or both.

3.2 The following nomenclature is used throughout this test method:

SP = static pressure drop across air terminal

A = internal cross section of duct, ft2 (m2)

De = equivalent diameter, ft (m)

F = amplification factor

K = flow coefficient

P = absolute static pressure, in. H2O (Pa)

Pv = velocity pressure, in. H2O (kPa)

ΔP = differential pressure, in. H2O (kPa)

ΔPt = total differential pressure, in. H2O (kPa)

V = air velocity, ft/min (m/s)

Ρ = air density, lbm/ft3 (kg/m3)

Qmax = maximum airflow setpoints of interest

Qmin = minimum airflow setpoints of interest

Qstpt = any setpoint

4 Instrumentation

4.1 Temperature Measurement.

Temperature measurements made to support determining the reference airflow are covered in Section 4.3. This section applies to other temperature measurements taken during testing.

Temperature measuring instruments shall meet the requirements of ASHRAE Standard 41.1-1986 (RA 2006)3 and the following:

4.1.1 Accuracy of the temperature measuring instruments shall be within ±0.18°F (0.1°C). The smallest scale division or output resolution of the temperature-measuring device shall not exceed the specified accuracy.

4.1.2 Temperature-measuring instruments shall be calibrated, on an annual basis, in the range of use by comparison to a national measurement standard, with uncertainties traceable to that national measurement standard, and shall be certified to provide the accuracies listed in Section 4.1.1.

4.2 Pressure Measurement. Refer to Section 5.3 for pressure measurements made to support determining the reference airflow.

Pressure measuring instruments shall meet the requirements of ASHRAE Standard 41.3-19894 and the following:

4.2.1 Accuracy of the duct pressure measuring instruments shall be within 5% of the measured pressure. The smallest scale division or output resolution of the pressure measuring device shall not exceed the specified accuracy.

4.2.2 Accuracy of the sensor recording the flow-probe signal (if the SUT includes flow-probe pressure taps) shall be within 5% of the reading.

4.3 Airflow Measurement. The reference airflow measuring system shall be IDD® certified and shall have the ability to provide 140% of the maximum airflow of the SUT at 2” H2O of operating pressure. The reference airflow measuring system shall have a minimum accuracy of +/- 1.5% over the entire range of the SUT. The reference airflow measuring system shall be calibrated, in the range of use, by comparison with a national measurement standard (e.g., a NIST standard). The reference airflow measuring system shall be calibrated as an assembly. Instruments shall be calibrated directly against the national standard, or through a traceable chain of not more than two intermediary instruments.

Airflow-measuring instruments shall meet the following:

4.3.1 Type of Instrument. Airflow measurements shall be made with one of the following types of instruments:

Velocity Pressure—laboratory pitot-static tube array with high-accuracy pressure sensors.

Differential Pressure—orifice plate or nozzles using differential pressure sensors similar to that indicated above for velocity pressure measurement.

Other Measuring Means—volumetric-airflow or velocity-measuring means.

4.4 Automatic Data Acquisition. Test data shall be automatically gathered from the prescribed sensors or instruments and logged for analysis and reporting purposes.

4.5 Calibration Mode Before Each Test. Before each test the instruments shall be set to zero to eliminate environmental disturbances.

5 Test Setup

Figure 5.1 illustrates the required test setup. The following sections describe the components and their relationships:

5.1 Reference to Terminal. The nominal test condition is a plenum between the airflow reference and the terminal. The plenum shall be sized so that the airflow velocity is no greater than 200 fpm for a minimum of 2 duct diameters. There shall be a straight, hard inlet to the terminal, at least 3 duct diameters long. The inlet-duct dimensions shall be the same size as terminal inlet (i.e., no transitions). The test specifier may designate other required inlet conditions.

5.2 Outlet from Terminal. The outlet is a straight duct, at least 3 diameters long. Downstream duct size shall match the terminal unit outlet, i.e., no transitions. A flow resistance (e.g., damper) may be installed downstream of this duct.

5.3 Airflow Reference. A reference airflow measuring system, conforming to Section 4.3, shall be installed with a plenum, as described in Section 5.1, separating the reference from the SUT.

5.4 Static Pressure Drop (ΔSP). The static pressure drop (also known as differential static pressure) across the SUT shall be measured. The high pressure port shall be located 1.5 equivalent duct diameters upstream of the SUT. The low pressure port shall be located 2.5 equivalent duct diameters downstream of the SUT.

5.5 Controller. The controller shall be mounted and connected per the manufacturer’s instructions.

5.6 Ductwork Leakage. Every joint of the ductwork between the reference airflow station and the unit under test must be sealed and tested. A duct pressure test shall be conducted at 2.0 in. H2O (1.5 kPa[JR1] ). The measured leakage rate shall be less than 10 ft3/min (5[JR2] L/s).

6 Test Methods

TEST METHODS

To ensure the highest level of comparability between the test results of two different SUTs, regardless of the documented accuracy of the comparison references involved, the test specifier shall require that the tests be performed in the same lab, using the same equipment, reference, and setup.

6.1 Calibration. The SUT is calibrated on the test installation, with the intention that the calibration process used in the lab represents the one that will be used in a field installation. The reference airflow measuring system, used for the system performance tests shall also be used for calibration.

The SUT shall be calibrated in the test installation according to the procedures recommended by the manufacturer.

6.2 IDD® Certification Test.

Test shall have a minimum of 700 test points with the airflow spacing in between points no greater than 25 FPM from 0 - 1000 FPM and no greater than 50 FPM from 1000 FPM – 2500 FPM. The test shall be run at operating pressures from 0.03” or less to 2” or greater[JR3] . The test shall consist of a minimum of 7 unique operating pressures with no single pressure consisting of more than 25% of the test data.

IDD® Gold Certification – 100-1 Turndown +-4% air flow accuracy, less than 150 FPM +-6 fpm

IDD® Silver Certification 100- 1 turn down, +- 6% air flow accuracy, less than 200 FPM +- 12 FPM

IDD® Bronze Certification 50-1 turndown, +- 10% airflow accuracy

7 Test Report

A report shall be issued with the results of the test run as described in section 6.2. The test data shall include the following.

Reference Airflow: The airflow measured by the reference airflow measuring system.

Static Pressure: The system static pressure at the inlet of the SUT measured against the atmospheric pressure.

Pressure Dop: The pressure drop across the unit as measured by upstream and downstream probes as described in 5.4.

Unit Airflow: The airflow as measured by the SUT.

FPM error: The error of the SUT when the airflow is less than 100 FPM. FPM error = Unit Airflow velocity - Reference Airflow velocity at SUT.

% error: The error of the SUT when the airflow is greater than 100 FPM. % error = (Unit airflow – Reference airflow)/Reference airflow

REFERENCES

ASHRAE RESEARCH PAPER 1353

ASHRAE STANDARD 195-2013

Definitions listed in ASHRAE Terminology of Heating, Ventilation, Air Conditioning, & Refrigeration.

ASHRAE Handbook—Fundamentals.

DISCLAIMER

Alpha Omega Labs, Inc., Inc. uses its best efforts to promulgate Standards and Guidelines for the benefit of the public considering available information and accepted industry practices. However, Alpha Omega Labs, Inc., Inc. does not guarantee, certify, or assure the safety or performance of any products, components, or systems tested, installed, or operated in accordance with IDD® Standards or Guidelines or that any tests conducted under its Standards or Guidelines will be nonhazardous or free from risk.

IDD® 2023-1 Intelligent Downstream Device Testing Standard

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