Centrifugal pumps operate under a wide range of conditions. To insure the life of your pump certain rules should be followed to protect it. Do not run the pump dry, and do not run the pump throttled on the suction side. Throttling on the suction side not only reduces the capacity, but also reduces pump efficiency, and more importantly, can cause serious damage to the pump due to cavitation. Cavitation occurs when the pressure at any point inside the pump drops below the vapor pressure of the liquid. The liquid flashes and forms vapor bubbles. These bubbles move along with the liquid into a higher pressure area, where the bubbles collapse or implode creating an area of low pressure. The implosion phenomenon is characterized by a crackling noise and sometimes by loud knocking as the vapor bubbles are collapsed. Repetition of this action causes a wearing away of the metal on the impeller and other parts of the pump, and if allowed to continue can result in serious damage to the pump.
Pump capacity can be effectively controlled by use of a throttling valve in the discharge piping. Most pumps can be operated for brief periods of time with the throttling valve closed without building up excessive pressure or overloading of the drive unit. Check for over heating and insure that the packing gland is properly lubricated with water to prevent the packing from burning up. Three to four drops of water per minute should be sufficient to ensure a properly lubricated packing gland.
I have had so many problems with my centrifugal pumps. I've spent way too much money trying to keep them up, and doing all of the work myself. It's time for me to get some professional help. Whatever professional means.
Posted by: Garfield | April 12, 2011 at 05:12 AM