Downloaded from https://www.everyspec.com MIL-STT)-81OC 3.1.4 Control items. In addition to the viability of inoculum control,, known susceptible substrates shall be inoculated along with the test item to insure that proper conditions are present in the incubation chamber to promote fungus growth. The control items shall consist of cotton duct 8.25-ounge strips that are 1.25 inches wide, that have been dipped into a solution containing..10percent glycerol, 0.1 percent potassium dihydrbgen orthophosphate (KH2P04), O.1 percent ammonium nitrate (NH4N03), 0.025 percent magnesium sulfate [MgS04.7H20), and 0.05 percent yeast extract (pH and from which the excess liquid has been removed.
The strips should be hung to air dry before being inoculated and plac&d int,othe chamber. 5.3), I 3.1.5 Inoculation of test and control item a. Mount the test control items on suitable fixtures or suspend from‘hangers. No cleaning of the test item shall be permitted for 72 hours prior to the beginning of the funguS test. Equipment handling prior to and during the fungus test shall be accomplishedwithout’contamination of the equipment. b. Precondition the chamber and its contents at: 30”C (86° F) and 97 1*2 percent relative humidity for at least 4 hours. c.
Inoculate the test and control items with the mixed fungus spore suspension (3.1.2) by spraying it on and into the test and control items (if not hermetically sealed) in the formof a fine mist from‘a previously sterilized atomizer or nebulizer. In spraying the test and control items, care should be taken to spray all surfaces which are exposed during use or maintenance. If the surfaces are nonwetting, spray until initiation of droplet coalescence. Incubation is to be started immediately following the inoculation. 4 3.1.6 Incubation of test items a.
Incubate test items under cyclic temperature and humidity conditions to include 20 hours of relative humidity at 95 t5 percent at an air temperature of tl° C (86° *2”F) followed by 4 hours of 100 percent relative humidity at fl”C (77° f2° F). b. After 7 days, inspect the growth on the control items to be assured that the environmental conditions are suitable for growth. If inspection reveals that the environmental conditions are unsuitable for growth, the I entire test shall be repeated. ,C. If the control items show satisfactory fungus growth, continue the “test for a period of 28 days from the time of inoculation or as specified in the equipment specification. METHOD 508.1 508.1-4 I