The innovative design and operation of a tubular PTFE diaphragm mechanism
has improved the reliability and reduced the maintenance requirement of
the new Codip air-operated pump range, which is available in the UK from
Michael Smith Engineers (MSE). Covering flow rates from 0 to 300
litre/min at discharge pressures of up to 10bar, the Codip pump is
operated by a compressed air supply via an independent automatic air
distributor to one side of a flat rubber air diaphragm.
This diaphragm is deflected, resulting in displacement of the inert
liquid inside the pump casing. As the inert liquid transmits pressure
uniformly to the PTFE tubular diaphragm, without any mechanical stress,
the service life of the tubular diaphragm is substantially increased.
Moreover, the pumps are secondary contained because the PTFE tubular
diaphragm is surrounded by an inert liquid that is sealed in place by the
air diaphragm, guaranteeing zero leakage in the unlikely event of a
diaphragm failure. MSE says that the absence of mechanical seals, packing
or O-rings means that the pumped liquid is effectively sealed from the
environment, so process fluid leaks are virtually impossible.
With small modifications, these pumps can handle liquids containing
solids or particles of up to 7mm diameter, to concentrations of 50%. And
thanks to the low-friction, non-stick properties of PTFE, they are also
suitable for the pumping of paints, polishes and glues.