Original designs of knife gate valves can be traced back to tools
which consisted of a gate, parallel sides and a pressure that was placed
into a main pipe line. The purpose of these valves was to shut off the
flow of liquids by use of the pressure on the upstream side of the
valve. Fluid pressure was vital in order to create the required force in
which to seal the valve. Various methods had been developed in the past
to achieve this, in which the gate would be mechanically pushed against
both faces to create a tight seal. This then resulted in the valve
action being independent of the pipe line pressure.

During the mid 1860