Give each of the knobs an egual number of turns and  in the same direction.  Turning the knobs clockwise, or to  the right,  inc~eases  the pressure necessary to operate the  valve.  Turning the knobs counter-clockwise, or to the left,  lowers the pressure necessary to operate the valve.  Tests  conducted on a number of modified valves in a valve test  chamber determined that ten complete turns on each of the  three knobs changes the pressure setting necessary to oper› ate the valve by 1/5 of an inch of H 2 0.  After a satisfactory resetting is found, add. leather  washers and screw the sealing caps in place again, then  safety the knobs to the clips on the shield.  Test setting  against the air manometers.  The use of the gas manometer  is misleading, except at, or very near, pressure height.  -33--