CONDENSATION—The  change  from  a gaseous  (or  vapor)  state  to  a  liquid  state. CONTAMINANT—Detrimental  matter  in  a fluid. CONTINUITY  EQUATION—The  mass  rate of fluid flow into any fixed space is equal to the mass flow rate out. Hence, the mass flow rate of fluid past all cross sections of a conduit is equal. CONTROL—A  device  used  to  regulate  the function  of  a  component  or  system. CONTROL,   CYLINDER—A   control   in which  a  fluid  cylinder  is  the  actuating  device. CONTROL,  ELECTRIC—A  control  actuated electrically. CONTROL,   HYDRAULIC—A   control actuated  by  a  liquid. CONTROL,   MANUAL—A   control   actuated by  the  operator. CONTROL,   MECHANICAL—A   control actuated by linkages, gears, screws, cams, or other mechanical  elements. CONTROL,   PNEUMATIC—A   control actuated  by  air  or  other  gas  pressure. CONTROL,  SERVO—A  control  actuated  by a feedback system that compares the output with the  reference  signal  and  makes  corrections  to reduce  the  difference. CONTROLS,   PUMP—Controls   applied   to positive-displacement variable delivery pumps to adjust  their  volumetric  output  or  direction  of flow. CONVERGENT—That   which   inclines   and approaches nearer together, as the inner walls of a tube that is constricted. COOLER—A heat exchanger, which removes heat  from  a  fluid. COOLER,   AFTERCOOLER—A   device   that cools  a  gas  after  it  has  been  compressed. COOLER,   INTERCOOLER—A   device   that cools  a  gas  between  the  compressive  steps  of  a multiple  stage  compressor. COOLER,   PRECOOLER—A   device   that cools  a  gas  before  it  is  compressed. CORROSION—The   slow   destruction   of materials  by  chemical  agents  and  electromechanical reactions. CYCLE—A   single   complete   operation consisting   of   progressive   phases   starting   and ending  at  the  neutral  position. CYLINDER—A   device   that   converts   fluid power  into  linear  mechanical  force  and  motion. It usually consists of a movable element, such as a  piston  and  piston  rod,  plunger,  or  ram, operating  within  a  cylindrical  bore. CYLINDER,  CUSHIONED—A  cylinder  with a  piston-assembly  deceleration  device  at  one  of both  ends  of  the  stroke. CYLINDER, DOUBLE-ACTING—A cylinder in which fluid force can be applied to the movable  element  in  either  direction. CYLINDER,   DOUBLE-ROD—A   cylinder with a single piston and a piston rod extending from  each  end. CYLINDER,   DUAL-STROKE—A   cylinder combination  that  provides  two  working  strokes. CYLINDER,  PISTON—A  cylinder  in  which the  movable  element  has  a  greater  cross-sectional area  than  the  piston  rod. CYLINDER,   PLUNGER—A   cylinder   in which the movable element has the same cross- sectional  area  as  the  piston  rod. CYLINDER,   SINGLE-ACTING—A   cylinder in  which  the  fluid  force  can  be  applied  to  the movable  element  in  only  one  direction. CYLINDER,    SINGLE-ROD—A    cylinder with  a  piston  rod  extending  from  one  end. CYLINDER,   SPRING-RETURN—A   cylin- der in which a spring returns the piston assembly. CYLINDER,   TANDEM—Two   or   more cylinders with interconnected piston assemblies. CYLINDER,   TELESCOPING—A   cylinder with  nested  multiple  tubular  rod  segments  which provide  a  long  working  stroke  in  a  short  retracted envelope. AI-2