Advantages of a single shaft vertical pump with tail-piece over multishaft vertical pump:
Vertical pumps are often required to be installed in applications where the liquids need to pumped out from great depths. One obvious solution is to have a multi-shaft long pump wherein the impeller and casing are submerged to the bottom most level of the liquid. However, this type of construction, although possible, has cost implications due to long shaft assemblies, and reliability may be hampered on periodic basis. A simpler solution is to go for a single shaft pump with a tail-piece arrangement. The tail-piece acts as a suction pipe and can empty the liquid to the bottom most level. The pump can be configured to stop working on emptying the tank and restart when the liquid level reaches the casing level again. In this configuration, there are inherent commercial and technical benefits during purchase and lifecycle of the pump.