Question

What is the purpose of a throttling valve? What are the implications of having a throttling valve prior to the pump inlet? Explain in terms of NPSH. i.e. what will happen if the valve is placed before the pump? or why do we put the valve after the pump instead of before the pump.

Answer 1

throttling valve: it is a device used for considerable pressure drop that caused the temperature drop thats why it is used in refrigeration system.

where to put the valve:

basically valve in pump are used to regulate the pressure and control the flow and also prevent any breakage of pump. and valve are placed both side of the pump that is one at suction of the pump and other at the outlet of the pump but Valves must be installed at the correct distance in order to insure maintenance and safety.

if the throttling valve placed at inlet instead of outlet of pump its regulation of pressure could not be maintained and flow become discontineous thats why throttling valve are placed at the outlet of the pump