SAE J994:2003 pdf download

SAE J994:2003 pdf download

SAE J994:2003 pdf download Alarm—Backup—Electric Laboratory Performance Testing
4.9 Rain, steam, and corrosion chamber.
5.Sound Pressure Level Test Setup-Sound pressure level Test – Two acceptable test methods will be described for measuring alarm sound pressure level.
5.1 Test Method 1—The alarm is located in a free field or an equivalent fully anechoic room.The microphone is directed toward the alarm sound output opening along the zero degree axis and at the distance specified bythe test requirements.
5.2Test Method 2—This is an alternative method for testing an alarm sound pressure level without the aid of an anechoic room.The alarm is located in a free field except for a horizontal reflecting plane and an acousticalbarrier partition.The acoustical barrier partition must be constructed.
5.2.10 REQuIRED MATERIALS FOR ACOUSTICAL BARRIER—Unless otherwise specified, all dimensional tolerances are ±10 mm.
a. Two pieces of particle board 900 mm x 1200 mm x 16 mm ± 2 mm thickb.Two Tripods adjustable to 1200 mm high c. Three each 200 mm x 200 mm x 90 degree sheet metal shelf brackets.
d. Two sections of sound absorbing foam of dimensions 1200 mm x 1350 mm and a thickness of 50 mmor greater. The sound absorbing foam should have an absorption efficiency of at least 50% at 50 Hzrising to at least 75%at 1000 Hz and greater.
5.2.2 CONSTRUCTION OF AcoUSTICAL BARRIER—Using the three 200 mm shelf brackets and screws,center and attach one of the 900 mm x 1200 mm particle boards perpendicular to the other 9o0 mm x 1200 mm baseboard to yield a 900 mm high wall as shown in Figure 1. Two brackets should be located 150 mm from theoutside edge on one side of the upright board.The third bracket should be mounted in the center on theother side of the upright board. Cover the exposed particle board with the sound absorbing foam as shown inFigure 1.
5.2.3 ALARMAND MICROPHONE LOCATIONS—Secure the alarm and microphone to their tripods. Position the alarmand microphone on opposite sides of and equidistant from the sound barrier at a height of 1200 mm ± 10 mmabove the horizontal reflecting plane. The distance between the two devices is specified in 6.3 of theFunctional Test Requirements.
5.3 Allowable Background Noise Level—While the sound pressure level test is in progress, the sound pressure level due to all sources other than the alarm device shall be at least 15 dB (A) lower than the sound pressurelevel of the alarm. This precaution reduces the effect of background noise on the sound pressure level testresults.
5.4 Sound Level Meter Settings—The sound level meter shall be set for fast response or equivalent and have the A-weighting network installed when checking sound pressure levels.
5.5Instrumentation Precautions—Proper usage of all test instrumentation is essential to obtain valid measurements. Operating manuals or other literature furnished by the instrument manufacturer should bereferred to for both recommended operation of the instrument and precautions to be observed. Specific itemsto review include:
5.5.1THE MICROPHONE—The type of microphone,its directional response characteristics,and its orientation relative to the ground plane and source of noise.