Digital fluid flow rate controller
AssigneeBodenseewerk Perkin-Elmer & Co., GmbH
InventorWinfried K. Gonner
Life of this patent
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Abstract
A precision digital flow rate control system particularly suitable for controlling the flow of an inert gas into the atomizing furnace of an atomic absorption spectrometer. The selection of the desired flow rate is made by switching the flow through one or more of the plurality of tubes having restrictors that limit the flow according to digital steps. The flow is switched by directional control solenoid valves that direct the flow either through a flow restrictor to the atomizing furnace or through an identical flow restriction to a vent. Therefore, there will always be a constant flow through each valve and, since the inlet pressure regulator will always see a constant load, it can maintain a very constant pressure to the valves.
Claims8
A flow rate control system for metering a predetermined fluid flow from an inlet manifold to a desired terminus, said system including:
- at least one directional control valve coupled to the manifold, said valve being switchable between first and second positions for directing the fluid from said manifold between first and second outlet conduits;
- a first fluid flow restrictor in said first outlet conduit, said first restrictor being calibrated to pass a predetermined flow of said fluid at a predetermined pressure to the desired terminus;
- a second fluid flow restrictor in said second outlet conduit, said second restrictor having a fluid resistance substantially equal with that of said first restrictor, said second restrictor coupled to a vent conduit for removing the fluid passing through said second conduit from the system;
- and
- electrical means for rapidly switching said control valve between said first and second positions whereby a continual and constant flow of said fluid will pass through said valve and whereby said switching will not alter the pressure within said manifold.
Dependencies are inferred from the claim text.