u.mallikarjuna

• Nov 18th, 2014

 

breaking effect on valves,impeller and shaft.

Abhimanyu

• Dec 16th, 2014

 

No effect or no harm to the pump and the impeller keeps on rotating

Rob

• Jan 20th, 2015

 

When the valve closes the flow rate through the impeller decrease significantly, there is still some re circulation. This causes the pressure at the valve to increase, the speed of the impeller to increase and the power to drive the impeller to decrease. There are a number of subtleties here associated with the design that could cause the fan to stall and actually reduce the pressure at the valve, but most are designed such that doesnt happen. Additionally there is some recirculation associated with the impeller in the stall state that requires power to drive it.

zia

• Jan 21st, 2015

 

the impeller keep rotating and due to friction with water the temperature will rise which will destroy the seal of the pumps..

Tanweer

• Feb 7th, 2015

 

It will increase the pressure in the flow chamber and pressure of mech seal or gland. Further increase in pressure the seal will fail. And ya the re circulation of flow will also increase the temperature inside. Ultimately it will effect on surface of impeller. It may damage.

jhangeer khan kk

• Mar 21st, 2015

 

Then will effect the motor .motor ll create high temperature and then will effect the shaft impelled and also line

ravi

• Mar 29th, 2015

 

May be nothing will happen. The pump will stall. Let us assume the discharge line length is continuously increased which will increase the discharge pressure. When the head pressure equals the centrifugal force which pushes the water in the pump, there will not be any discharge, but still the pump will do its work, water will move up and down. The pump stalls. A similar situation will be created in this The head pressure is created by closing the valve. Suppose if the pressure is more on discharge side water will flow back to suction side. This effect is called as surging in centrifugal pumps.

prasad

• Jun 21st, 2015

 

Water hammering will occur due to the discharge that results from the pump.

sandip

• Jun 29th, 2015

 

Back pressure are induced in the pump due to that they can permanently damage position.

Ahmed El-Shamy

• Dec 25th, 2015

 

Nothing will happen to the pump if it is made in a good materials, the pump still works and the pressure of water will increase and so the temperature until the water evaporates.

chintan parekh

• Apr 16th, 2016

 

There is two types of pumps. One is positive displacement type of pump, another is reciprocating type of pump. If we close the exit valve of positive displacement type of pump than, the fluid will comes out from any where, it will make space for coming out by bursting of pipe. While in reciprocating type the pump will burn out and stops working.

pawan kumar singh

• Nov 1st, 2016

 

When the discharge valve is closed in the running condition of a pump then the friction between pump impeller and liquid generates heat which increases continue and hence the fluid gets vaporized which causes problems of cavitation.

eiddy

• Jun 1st, 2017

 

Water hammer phenomena takes place due to the pressure rise.
Closing the valve suddenly causes revers flow (reaction flow) may damage the pump or elbows if exist.