Downloaded from https://www.everyspec.com MIL-STD-81OC 10 March 1975 METHOD 508.1 FUNGUS 1. PURPOSE. The fungus test is used to determine the resistance of equipment to f-d to determine if such equipment is adversely affected by fungi under conditions favorable for their development, namely high humidity, warm atmosphere, and presence of inorganic salts. 1.1 General effects. Typical prob1ems caused by fungi growing on equipment are: a. Micro-organisms digest organic materials as a normal metabolic process thus degrading the substrate, reducing the surface tension, and increasing moisture penetration. b.
Enzymes and organic acids produced during metabolism diffuse out of the cells and onto the materials and cause metal corrosion, glass etching, hardening of grease, and other physical and chemical changes to the materials, such as insulation resistance and arcing. c. The physical presence of mi~ro-organismsproduce living bridges across components which may result in electrical failures. 2. APPAMTUS . The apparatus required to conduct this test consists of chambers of cabinets together with auxiliary instrumentationcapable of maintaining the specified condition of temperature and humidity. Provisions shall be made to prevent condensation from dripping on the test item.
There shall be free circulation of air around the test item and the contact area of fixtures supporting the test item shall be kept to a minimum. When forced air is employed, the flow should not exceed 1 meter per second over the surface of the test specimen. 3. PROCEDURE 3.1 Procedure I 3.1.1 Preparation of mineral-salts solution. The solution shall contain the following: Potassium dihydrogen orthophosphate (KH2p04) . . . . . . . . 0.7 g Potassium monohydrogen orthophosphate (K2HP04) . . . . . . . . 0.7 g 508.1-1 MSTHOD 508.1 10 March 1975