Necessary pump pressure for equal velocity fluid delivery (for soluble oil) The principle of equal velocity fluid delivery (according to H. W. Ott) describes the nozzle exit velocity of a coolant jet as being equal to the wheel's peripheral or surface speed, whereby pump pressures and nozzle cross-section are linked interdependently. The table below serves as a guideline to establish the pump pressure in bar (1 bar equals 14 psi) for given surface speeds. |