Fluid admitted under piston 1 moves it upward so that it clamps shell case 3 through pad 2 against crosspiece 4 which is secured to the base by two columns 5. A tube with valve 6 passes through the crosspiece to release air when the shell case is filled with water. When water appears in the valve, it is closed. Water for the test is delivered through tube 7.
$3784$SHP,FD$