METHOD FOR MONITORING FLUID FLOW FROM A VOLUMETRIC PUMP

A method for determining if fluid is being displaced by a volumetric pump. The volumetric pump (30) includes an inlet cracking valve (46) and an outlet cracking valve (52) disposed on opposite sides of a plunger (48) used to displace fluid by compressing flexible tubing (34). During a pumping segmen...

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Bibliographische Detailangaben
Hauptverfasser:	CHUNG-YOU CHARLES WU, VERNON R NATWICK, JOSEPH E DOLL, MICHAEL W LAWLESS
Format:	Patent
Sprache:	eng
Schlagworte:	BLASTING DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROMTHE BODY GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS HEATING HUMAN NECESSITIES HYGIENE LIGHTING MECHANICAL ENGINEERING MEDICAL OR VETERINARY SCIENCE POSITIVE DISPLACEMENT MACHINES FOR LIQUIDS PUMPS PUMPS FOR LIQUIDS OR ELASTIC FLUIDS TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE WEAPONS
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Beschreibung
Zusammenfassung:	A method for determining if fluid is being displaced by a volumetric pump. The volumetric pump (30) includes an inlet cracking valve (46) and an outlet cracking valve (52) disposed on opposite sides of a plunger (48) used to displace fluid by compressing flexible tubing (34). During a pumping segment of a pumping cycle for the volumetric pump, the outlet cracking valve is closed with a cracking force that compresses the flexible tubing until the pressure of the fluid displaced by the plunger exceeds a cracking pressure, at which time the outlet cracking valve opens to enable fluid flow from the volumetric pump. A cracking flexure (182) provides the cracking force. As the outlet cracking valve opens in response to the fluid pressure exceeding the cracking pressure, a flow detector (54) mounted to the cracking flexure responds to the stress generated in the cracking flexure thereby, producing a signal indicative of fluid flow from the volumetric pump. Since a compressible gaseous fluid in the pumping portion of the flexible tubing does not develop the cracking pressure, the flow detector also provides an indication when a source of liquid (31) for the volumetric pump has run dry. The method comprises the steps of processing the signal to determine if it exceeds a predefined threshold that varies as a function of the rate at which the pump is set to deliver fluid.