Eductors / Venturis

With a vessel sampling system vacuum is required to draw the sample liquor up the dip tube and into the sampling system. Usually this is available from the central vacuum system. However where this is not available we are able to supply the sampling system with an educator which can generate sufficient vacuum being powered by compressed gas, either nitrogen or air.

Venturis are named after the Italian physicist Giovanni Battista Venturi (1746-1822) who discovered that passing a fluid through a tube with a constricted throat brought about an increase in velocity through the restriction with a consequent drop in pressure at the entrance to the throat.

This principle is used in modern day eductors, the pressure drop being so much as to create a vacuum, depending on eductor choice the vacuum created can be surprisingly high, drawing a column of water 5m high is not uncommon.
CRP use eductors on vessel samplers when a vacuum service is not available, they are connected directly to the top manifold of the sampler. The compressed gas to drive the eductor is controlled with a ball valve mounted rigidly to a stainless steel bracket. The exhaust gas can be vented to a scrubber system or piped back into the vessel if required. Eductors can be provided in stainless steel, PTFE or PVDF to suit the chemistry of the sample liquid.