Environmental treatments.

§ 84.307 Environmental treatments. (a) Four units submitted for approval will be tested for capacity and performance, pursuant to the requirements of §§ 84.303 through 84.305, after exposure to environmental treatments simulating extreme storage temperatures, shock, and vibration. (b) The units will be stored for 16 hours at a temperature of −45 °C and for 48 hours at a temperature of 71 °C. Units will be returned to room temperature between high and low temperature treatments. The maximum rate of change for thermal loading shall not exceed 3 °C per minute and constant temperatures shall be maintained within ±2 °C. (c) The units, in the casing in which they are deployed for individual use, will be subjected to physical shock according to the following procedure: (1) The unit will be dropped six times from a height of 1 meter onto a concrete surface; and (2) Each drop will test a different orientation of the unit, with two drops along each of its three major axes (top to bottom, left to right, and front to back). (d) The units will be subjected to vibration according to the following procedure: (1) The unit will be firmly secured to a shaker table, which will be vibrated with motion applied along a single axis for 180 minutes; (2) The unit will be vibrated one axis at a time along each of three axes for a total of 9 hours; and (3) The vibration frequency regimen applied to each axis will be cyclical, repeating the sequence and specifications provided in Table 5 every 20 minutes. Table 5—Vibration Test Sequence Sequence Frequency (Hertz) Acceleration g (±peak) 1 5–92 2.5 2 92–500 3.5 3 500–2000 1.5