Fluid flow control system having capillary fluid flow restrictor

Abstract

A fluid flow rate control system and method comprises a capillary tube having a proximal end that projects into a chamber with a cross-sectional area that is larger than or equal to the fluid supply tube's cross-sectional area. The inner cross-sectional area of the capillary tube is configured less than the inner cross-sectional area of the chamber. The chamber has a volume large enough to slow the fluid conducted to it by the upstream fluid line to permit contaminants to fall out of solution. In another aspect, a sleeve is used to mount the capillary tube into the chamber. The sleeve provides a mounting surface for tube segments from the pump and downstream of the capillary restrictor.

1 - 12 . (canceled) 
     
     
         13 . An infusion system comprising:
 a pump;   a supply tube segment in fluid communication with the pump to conduct fluid from the pump, the supply tube segment having a distal end and a supply tube inner diameter; and   a capillary flow restrictor in fluid communication with the distal end of the supply tube segment for receiving fluid from the pump and controlling the flow rate of that fluid, the capillary flow restrictor comprising:   a housing connected with the supply tube segment for receiving fluid from the pump, the housing having a proximal end;   a sleeve disposed within the housing and having a proximal end, the sleeve disposed so that the proximal end of the sleeve is not coincident with the proximal end of the housing, thereby forming a chamber having an inner chamber cross sectional area; and   a capillary tube mounted partially within the sleeve, the capillary tube having an inner cross-sectional area smaller than the chamber inner cross-sectional area and having a length, the capillary tube having a proximal segment extending outwardly from the sleeve and projecting into the chamber;   wherein the inner cross-sectional area of the chamber is configured to be larger than the inner cross-sectional area of the supply tube so that the chamber volume resulting from the length of the chamber and the chamber inner cross-sectional area slows the flow rate of the fluid received from the supply tube so that contaminants will fall out of solution of the fluid and into the chamber, whereby such separated contaminants will not be conducted by the capillary tube.   
     
     
         14 . The infusion system of  claim 13  wherein the inner cross-sectional area of the capillary tube is less than the inner cross-sectional area of the chamber. 
     
     
         15 . The infusion system of  claim 13  wherein the capillary tube has a distal end that is in fluid communication with a distal segment of a second tube that conducts fluid flowing through the capillary tube to a downstream location at the flow rate controlled by the capillary tube. 
     
     
         16 . The infusion system of  claim 13  wherein the capillary tube is surrounded by a sleeve over less than the entire length of the capillary tube, wherein the sleeve mounts the capillary tube such that the proximal end of the capillary tube projects into the chamber, the sleeve having a radially-outwardly extending mounting flange;
 a first housing surrounding the sleeve and interconnecting with the distal end of the fluid supply tube forming the chamber between the distal end of the fluid supply tube and the sleeve wherein all flow through the chamber must proceed through the capillary tube; 
 a second housing surrounding the sleeve and interconnecting with a downstream segment of a second tube into which the capillary tube feeds fluid; 
 the first and second housings mounted over the sleeve and abutting the mounting flange. 
 
     
     
         17 . The infusion system of  claim 13  wherein the capillary flow restrictor is color coded to indicate an intended flow rate through the capillary flow restrictor. 
     
     
         18 . The infusion system of  claim 13  wherein the capillary tube comprises glass or polyvinylchloride (PVC). 
     
     
         19 . The infusion system of  claim 16 , wherein the radially-outwardly extending mounting flange extends to a distance similar to that of the first and second housings. 
     
     
         20 . A method for restricting flow of medicament through a fluid supply tube comprising:
 pumping medicament into the fluid supply tube at a first instantaneous velocity;   slowing the velocity of medicament through the fluid supply tube at a point downstream to a second instantaneous velocity that is less than the first such that contaminants in the medicament fall out of solution and are separated from the liquid of the medicament; and   conducting the liquid of the medicament from the point where the contaminants are separated from the segment preventing the contaminants from further downstream flow.   
     
     
         21 . The method of  claim 20 , further comprising:
 operating the point downstream at a substantially constant temperature.   
     
     
         22 . The method of  claim 21 , wherein the operating comprises operating the point downstream by placing on a patient's skin. 
     
     
         23 . A method of removing contaminants in a fluid in a tube by:
 allowing the fluid to flow into a chamber from a distal end of the chamber, the volume of the chamber being chosen to decrease instantaneous velocity of the fluid entering the chamber; and   conducting the fluid out of the chamber through a capillary tube mounted on a sleeve at a proximal end of the chamber;   wherein the capillary tube has an inner cross-sectional area smaller than an inner cross-sectional area of the chamber and wherein the capillary tube projects outwardly from the sleeve into the chamber.   
     
     
         24 . The method of  claim 23 , further comprising:
 operating the chamber at a substantially constant temperature.   
     
     
         25 . The method of  claim 24 , wherein the operating comprises operating by placing the chamber on a patient's skin.