APPENDIX I GLOSSARY (NOTE: Refer to page AI-4 for a glossary of chemicals used in water treatment.) ABFC—Advanced Base Functional Components. AERATOR—Device  for  removing  certain  dissolved gases during water treatment. AEROBIC   DECOMPOSITION—Bacterial decomposition that occurs in the presence of oxygen. AFTERCOOLER—A device which cools the final discharge from a compressor. ANAEROBIC   DECOMPOSITION—Bacterial decomposition  occurring  in  the  absence  of  free oxygen. ANGLE—A figure formed by two lines or planes extending from, or diverging at, the same point. ANGLE  VALVE—A stop valve that is actually a combination valve and elbow since its outlet branch is at right angles to its inlet branch. AQUIFER—A geological water-bearing formation that can provide water for wells. ARCHITECTURAL  PLAN—Show    design    and composition of a structure, including floor plans, building sections, and elevations. BACK-PRESSURE VALVE—A  valve  similar  in design to a low-pressure valve that is capable of opening  independently  of  the  pressure,  thereby giving  free  exhaust. BACTERIA—Living organisms, microscopic in size, which consist of a single cell.  Most bacteria use organic matter for their food and produce waste products as a result of their life processes. BILL OF MATERIAL—A   list   of   all   materials required to complete an installation based on takeoffs and estimates. BLUEPRINT—A  photographic  print  consisting  of white lines on a blue background. It is used for copying  architect’s  plans,  drawings,  and  so forth. BUSHING—A plumbing fitting used to reduce from one size of pipe to another size of pipe. BUTTERFLY  VALVE—A two-position valve with a vertical or horizontal disk. BTU—British thermal unit, a measurement of heat. CALCIUM  HYPOCHLORITE—CaC1₂O₂, a granular white powder used to disinfect water. CAP—A plumbing fitting used to close off a length of pipe. CAULKING  IRON—A   plumbing   tool   used   to compact or caulk lead wool or poured lead into a  cast-iron  pipe  joint. CBMU—Construction Battalion Maintenance Unit. CBR—Chemical, Biological, and Radiological. CBU—Construction Battalion Unit. CEC—Civil Engineer Corps. CENTIGRADE —A thermometric scale in which 0 degrees represents the freezing point and 100 degrees represents the boiling point of water at a pressure of 1 atmosphere. Is used with metric units  of  measure.  Equal  to  the  international thermometric scale of Celsius. CHECK VALVE—An automatic nonreturn valve or a valve which permits a fluid to pass in one direction but automatically closes if the fluid begins to pass in the opposite direction. CHLORINATION —The  disinfection  of  a  substance or container by a chlorine chemical or gas. CHLORINE—A natural chemical element (Cl). A powerful disinfectant, used extensively in water treatment. As a gas, its color is greenish yellow, and it is 2 1/2 times heavier than air. As a liquid, its color is amber, and it is about 1 1/2 times heavier than water. It is an oxidizer and is toxic to all organisms and corrosive (in the presence of water) to most metals. CIVIL PLANS—The   essential   data   for   layout, location, and site for a construction project, including   boundaries,   elevations,   roads, utilities, structures, and references of both existing  and  finished  construction. AI-1