ANSI AHRI -270-2008 pdf download Sound Performance Rating of Outdoor Unitary Equipment
4.2.1 In the first step, the sound measurements shall be made with the equipment operating at the ARI standard thermal rating condition in ARI Standards 210/240 and 340/360. 4.2.2 In the optional second step, the compression equipment shall be turned off and sound readings taken with only the fan(s) operating. During this step, the temperature of the ambient air entering the unit shall be within ± 2.0 °F [1.1 °C] of the temperature measured during compressor operation.
4.3 Data to be Taken. Sound data taken shall be per ARI Standard 220 in One-Third Octave Bands (100 Hz to 10,000 Hz are required, 50 Hz to 80 Hz are optional) in accordance with the procedure specified above for the type of test being conducted.
4.4 Air Velocity at Measurement Positions. Sound measurements shall not be made when the air velocity over the microphone exceeds 1,100 ft/min [5.6 m/s]. A foam windscreen shall be installed on the microphone which shall not affect the microphone response by more than ± 1 dB for frequencies of 20 to 4,000 Hz or ± 1.5 dB for frequencies above 4,000 Hz.
4.5 Unit Installation. The unit under test shall be located within the reverberation room as specified in ARI Standard 220. Where applicable, unit supply and return ducting shall be lagged to prevent sound radiating from them (refer to ARI Standard 260 for guidance in duct construction). In the case of wall-mounted equipment, the mounting wall shall be of heavy masonry or equivalent construction, or an auxiliary mounting platform shall be provided to minimize wall vibration effects. Care must be taken to minimize the noise radiating from the connecting refrigerant piping on split systems.
4.6 Unit Operation. The unit under test shall operate as specified below.
4.6.1 Electrical Characteristics. Tests shall be performed at the nameplate rated voltage, phase, and frequency at the unit service connection. For units with dual nameplate voltage ratings, standard sound tests shall be performed at both voltages. The higher of the two ratings obtained shall be the ARI standard sound rating or both ratings shall be published.
4.6.2 Outdoor-Side Air Quantity. All tests shall be made at the outdoor-side air quantity specified by the manufacturer where the fan drive is adjustable, or, where the fan drive is direct-connected, they shall be determined at the outdoor air quantity inherent to the unit when operated with all of the air resistance elements associated with inlet louvers and any duct work and attachments normally supplied as part of the unit. Once established, the outdoor air circuit shall remain unchanged for all tests prescribed herein, except for the reduced ambient conditions operation (Refer to 4.6).
4.6.3 Unit Operation Requirements. All components required to produce the standard rating capacity under ARI Standard 210/240 or ARI Standard 340/360 shall be operated while data is being taken and the test conditions shall be identical to the standard (cooling) condition temperatures specified in ARI Standard 210/240 or ARI Standard 340/360.