Downloaded from https://www.everyspec.com MIL-STD-81OC 3. PROCEDURE 3.1 Procedure I 3.1.1 Temperature. The test shall he conducted with a temperature in the expostirezone maintained at 35° C (9S°F). Satisfactorymethods for controllingthe temperature accurately are by housing the apparatus in a properly controlled constant temperature room, by thoroughly insulating the apparatus and preheating the air to the proper temperatureprior to atomi- zation, or by jacketing the apparatus and controllingthe temperature of the water or of the air used in the jacket. The use of immersion heaters within the chamber for the purpose of maintaining the temperature within the exposure zone is prohibited.
3.1.2 Aarnization. Suitable atomization has been obtained in chambers having a volume of less than 12 cubic feet under the following conditions: a. Nozzle pressure shal1 be as low as practicable to produce fog at the required rate. ,,, :., ‘,,,b, Orifices between 0.02 and O.03 inch in diameter. c. Atomization of approximately 3 quarts of salt solution per 10 cubic feet of chamber volume per 24 hours, When using large size chambers having a volume considerably in excess of ;. 12 cubic feet, the conditions specified may require modification to meet ,,..the requirements for operating conditions. ..j. .3.1.3 Placement of salt fog collection receptacles.
The salt fog conditions maintained in al1 parts of the exposure zone shall be such that a clean fog collecting receptacle placed at any point in the exposure zone will collect from O.5 to 3 milliliters of solution per hour for each 80 square centimeters of horizontal collecting area [10 centimeters diameter) based on an average test of at least 16 hours. A minimum of two receptacles shall be used, one placed nearest to any nozzle and one farthest from all nozzles. Receptacles shall be placed so that they are not shielded by test items and so no drops of solution from test items or other sources will be collected.
3.1.4 Measurement of salt solu’h$on.The solution, collected in a manner specified in 3.1,3, shall have the sodium chloride content and pH specified in 2.4 when measured at a temperature of,35°C (95”F). The salt solution from all collection receptacles used can be combined to provide that quantity required,for the measurements.specified. 509.1-6 METHOD 509.1 -.