STANDARD RULES FOR CENTRIFUGAL PUMPS

Here was some basic rule for how to use centrifugal pumps efficiency and safety. And it’s very important.

• Never install a suction line smaller than the pump suction, as this
  can cause NPSH deprivation.
• Never close or throttle the pump suction valve while the pump is
  operating.
• Prime the pump and purge all air from the casing before starting, to
  prevent seal damage and vapor locking.
• Never run the pump dry.
• Pump discharge should always be above the pump suction, to
  prevent air from being trapped in the casing.
• Ensure adequate NPSHA.
• Ensure that the suction line is adequately submerged, to prevent an
  air vortex from forming.
• Ensure that fluid transferred is free of air.
• Ensure that suction and discharge piping always lead upward. Avoid
  lines that go up over and back down, as this will cause air to become
  trapped in the line. If this is unavoidable, provide a means for
  bleeding air out of the line.
• When sizing centrifugal pumps, work in feet, not psi.
• Ensure that the pump driver is turning in the proper direction.
• Oil-lubricate bearings for speeds above 2400 rpm.
• Oil-lubricated pumps must be operated in a level horizontal
  position.
• Do not allow the pump to support suction and discharge piping.
• Ensure that the pump and driver are properly aligned after all piping
  and positioning has been completed.
• Size the pump to produce head to meet the system requirements or
  provide means of throttling the discharge line. Proper sizing is
  desirable.
• Size the pump for the maximum flow rate, temperature, and head
  that may be required.
• The suction line should be as short as possible.
• The suction line should have a straight run at least two pipe
  diameters long directly in front of the pump suction.