As well as this, Butterfly valves are used on fire apparatus and
typically

are used on larger lines, such as front and rear suctions and
tank to pump lines.

A Butterfly valve is also a type of flow

control device, used to make a
fluid start or stop flowing through a section of pipe. The valve is
similar in operation to a

ball valve.

Some supplementary tips

Butterfly valves on water lines should be manually operated only through
a

geared mechanism to prevent slamming