Downloaded from https://www.everyspec.com MIL-STD-2031 (SH) 30.2.2 IICN Measurements. For the HCN measurements a gas-tight syringe shall be used to obtain a sample every 3 minutes to be analyzed with a gas chromatography equipped with a thermionic detector. 30.2.3 Continuous monitoring. Continuous monitoring of 02, C02, and Co shall bc accomplished by the removal of some of the products from the chamber. To provide concurrent monitoring of these gases, a gas sampling port, sample tubing and pump system shall be used to provide a flow of approximately 0.5 liters/rein/gas.
Two liters per minute shall be removed via the gas sampling port Ioeated at the animal nose level in the geometric center of the exposure chamber, analyzed and pumped back into the chamber (figure 8) at the left side of the chamber above the furnace. 30.2.4 Toxicity levels. Under some circumstances assessing the toxicity of generated gases instead of oxygen deprivation may be important. Oxygen shall be supplied to the exposure chamber as needed to maintain the concentration between 16-21 percent. If this is done, the total volume shall be corrected for this addition when calculating the mass loading of combustion products (chamber volume plus added volume at room temperature).
30.2.S Calibration. Instrumentation for the meastn-ement of CO, C02, and 02 shall be calibrated before each test using standard gas mixtures of a combination of CO, C02, and 02 in nitrogen. The return tubes shall be disconnected during calibration of the analytical instruments to prevent the inadvertent accumulation of calibration gases in the animal chamber. 303 Tempemture measwemanm Suitable temperature sensors shall be placed in the air close to the animals’ noses. These instruments shall be measure temperature to 60 (140 “F). The environmental temperature of the chamber shall be recorded continwusly during the 30 minute animal exposure. 30.4 Animal exposure system.
A nominal 200 liter rectangular animal exposure chamber including the combustion furnace shall be used. The exposure chamber shall be made of 1.2 cm (0.5 inch) clear polymethylmethacrylate with inside dimensions of 122x36x 46 cm (48x 14x 18 inches). Six animal ports shall be positioned as shown on figure 7 and shall be constructed of polymethylmethacrylate tubing 6.3 cm (2.5 inch) id having a 0.3 cm (1/8 inch) wall thickness. A blow-out panel shall be provided in tbe top of the exposure chamber on the right side away from the furnace to provide pressure relief in case of an explosion. 30.4.1 Animal nstralners.
Animal restrained designed to permit exposure of only the heads of the rats shall be used. Figures 9 and 10 provide details for a typical animal restrainer system. 30.5 Animals. Adult male rats weighing 22S-300 grants that are 3-4 months of age shall be used. F~cher-344 rats or equivalent shall be used. Healthy animals shall be used in testing. 36