A-A-52525A
3.3.4.2 Waterproofness. Horns (type I and II only) and buzzers shall be completely submerged at least 25.4 mm below the surface of a 5% by weight solution of sodium chloride contained in a sealed chamber. Horns and buzzers shall show no evidence of bubbles escaping from the interior while operated at the design voltage and air pressure specified in table I for 30 minutes with the chamber pressure at 42 kPa above and below atmospheric pressure. Bubbles created from entrapped air on the exterior surfaces of the horns and buzzers shall be disregarded. After submergence in the saline solution, horns and buzzers shall meet the following requirements:
a. Water shall not be present on the interior surfaces or components.
b. Evidence of insulation breakdown or other damage detrimental to the mechanical or electrical operation shall not be present after withstanding three 5-hour periods of dry operation at the design voltage and air pressure specified in table I.
c. All sound performance requirements shall be subsequently met.
3.3.4.3 Connector and terminal strength. Horns and buzzers shall conform to the waterproofness requirements after the connectors and terminals are subjected to a 220 Newton (N) pull for 15 minutes, first in a direction normal to and then in a direction parallel to their respective longitudinal axes. The normal axes pull shall be made from their mating ends.
3.3.4.4 Valve airtightness. Type I horns shall show no evidence of bubbles escaping past the air valve from the air valve enclosure while connected to a 620 kPa air source, with control disconnected, and submerged in water for 10 minutes with the projector opening directed towards the air-water boundary. Type I horns shall conform to this requirement before and after continuous and intermittent operation.
3.3.4.5 Salt fog. Horns and buzzers shall conform to the sound performance requirements and shall evidence no corrosion after exposure to a salt fog atmosphere in accordance with ASTM B117 for 200 hours.
3.3.4.6 Fungus. Horns and buzzers shall show no evidence of fungus growth affecting operation and shall conform to the sound performance requirements after exposure to conditions favorable to fungus growth as specified in the contract or order (see 7.2). Duration of exposure shall be 90 days.
3.3.4.7 Vibration. Horns and buzzers shall show no evidence of disintegration of component materials or assemblies and shall conform to the sound performance requirements after being subjected to a simple harmonic motion having an amplitude of 0.8 mm and a frequency that is uniformly varied from 10 to 55 Hz and back to 10 Hz in approximately 1 minute. Motion shall be applied for at least 1 hour in the direction of each of the three major axes. Type I horns shall also conform to the valve airtightness requirement after being subjected to the simple harmonic motion.
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