VT Pump or Vertical turbine pump [deep well turbine pump] is vertical axis centrifugal or mixed flow type pump comprising of stages which accommodate rotating impellers and stationary bowls possessing guide vanes.
These pumps are used where the pumping water level is below the limits of Volute centrifugal pump. They have higher initial cost and are more difficult to install and repair. The pressure head developed depends on the diameter of impeller and the speed at which it is rotated. The pressure head developed by single impeller is not great. Additional head is obtained by adding more bowl assemblies or stage.
Construction: It has three parts:
The pump element is made up of one or more bowls or stages. Each bowl consists of an impeller and diffuser.
It connects the bowl assembly and pump head and conducts water from former to later.
It consists of base from which the discharge column, bowl assembly and shaft assembly are suspended.
An vertical turbine pump close coupled to a small diameter submersible electric motor is termed as “submersible pump”. The motor is fixed directly below the intake of the pump. The pump element and the motor operate under submerged condition. It can be used in very deep tube well where a long shaft would not be practical.
Construction: It consist of pump and motor assembly, a discharge column, a head assembly and a water proof cable to conduct the electric current to a submerged motor.
It consists of propelling shaft, usually made of stainless steel and bronze impellers. Water enters the pump through a screen located between motor and the pump.
The motor is enclosed in steel case filled with light oil of high electric strength. A mercury seal placed directly above the amateur prevents oil leakage or water entrance at point where the drive shaft passes through the case to the impellers.