Centrifugal Pump Protection:

A centrifugal pump is dead-headed while it is operated along with no flow by it, for instances, along with a closed discharge valve or against a seated check valve. The impeller will churn the similar volume of water as it rotates in the pump casing if the discharge valve is closed and there is no other flow path available to the pump. This will increase the temperature of the liquid (because of friction) in the pump casing to the point in which it will flash to vapor. The vapor could interrupt the cooling flow to the pump's packing and bearings, causing excessive wear and heat. It will become damaged if the pump is run in this condition for a significant amount of time.

While a centrifugal pump is installed within a system like that it might be subjected to periodic shutoff head conditions, it is essential to gives a few means of pump protection. A method for protecting the pump from running dead-headed is to gives a recirculation line from the pump discharge line upstream of the discharge valve, back to the pump's supply source. A recirculation line should be sized to permit sufficient flow by the pump to avoid overheating and damage to the pump. Protection might also be completed through use of an automatic flow control device.

Centrifugal pumps have to also be protected from runout. Runout could lead to cavitation and could also cause overheating of the pump's motor because of excessive currents. A method for ensuring in which there is always adequate flow resistance at the pump discharge to avoid excessive flow by the pump is to place an orifice or a throttle valve instantly downstream of the pump discharge. Properly designed piping systems are extremely important to protect from runout.