Flowmeter for the precision measurement of an ultra-pure material flow

Abstract

A Coriolis flowmeter for the measurement of a process material requiring an ultra high level of purity. This is achieved by forming the entire Coriolis flowmeter of a PFA plastic material that does not transfer ions from the Coriolis flowmeter to the process material flowing through the flowmeter.

1 . A Coriolis flowmeter for measuring a process material flow having an ultra high level of purity, said Coriolis flowmeter comprising: 
 a base;    flow tube apparatus adapted to receive said process material flow, said flow tube apparatus is formed of a material, such as PFA, that does not transfer ions from said flow tube apparatus to said process material;    end portions of said flow tube apparatus coupled to said base to create substantially stationary nodes at said end portions;    a driver coupled to said flow tube apparatus for vibrating said flow tube apparatus containing said process material flow;    pickoff means coupled signalwise to said flow tube apparatus for generating signals representing induced Coriolis deflections of said vibrating process material filled flow tube apparatus; and    meter electronics that receives said signals from said pickoff means and generates output information pertaining to said process material flow.    
     
     
         2 . The Coriolis flowmeter of  claim 1  characterized in that said flow tube apparatus defines a substantially straight single flow tube.  
     
     
         3 . The Coriolis flowmeter of  claim 1  characterized in that the entirety of the wetted flow path of said Coriolis flowmeter comprises a PFA substance.  
     
     
         4 . The Coriolis flowmeter of  claim 1  characterized in that said flow tube apparatus defines more than one flow tube.  
     
     
         5 . The Coriolis flowmeter of  claim 1  characterized in that said pickoff means is an electromagnetic device having a magnet connected to said flow tube apparatus and further having a coil.  
     
     
         6 . The Coriolis flowmeter of  claim 1  characterized in that said pickoff apparatus comprises a light source that emits a beam and an optical detector that receives said beam, said beam is oriented substantially transverse to said flow tube; 
 said light source and said optical detector are spaced apart from said flow tube on opposite sides of said flow tube apparatus;    said flow tube apparatus is positioned between said light source and said optical detector to alter the characteristics of a light beam received by said optical detector from said light source, said optical detector is responsive to said alteration to generate said signals representing said Coriolis deflections.    
     
     
         7 . The Coriolis flowmeter of  claim 1  characterized in that said base has a lower surface and an inner pair of upwardly extending walls as well as an outer pair of upwardly extending walls parallel to said inner walls; 
 openings in each of said upwardly extending walls are coaxially aligned to receive said flow tube apparatus.    
     
     
         8 . The Coriolis flowmeter of  claim 1  characterized in that said base is substantially unshaped and has a lower surface and a pair of upwardly extending walls proximate sides of said base; 
 openings in each of said upwardly extending walls are coaxially aligned to receive said flow tube apparatus.    
     
     
         9 . The Coriolis flowmeter of  claim 1  characterized in that said base is a solid rectangular element defining a parallelepiped; 
 said flow tube apparatus is connected to posts affixed to said base between upwardly extending walls affixed to a top surface of said base.    
     
     
         10 . The Coriolis flowmeter of  claim 2  characterized in that said flow tube apparatus comprises said single flow tube and that said base has a mass substantially greater than the mass of said flow tube with process material.  
     
     
         11 . A Coriolis flowmeter for measuring a flow of process material having an ultra high level of purity; 
 said Coriolis flowmeter comprising:    a single flow tube formed of a material, such as PFA, that does not transfer ions from said single flow tube to said process material;    said single flow tube has high flexibility and further has a stiffness substantially lower than a metal or glass flow tube;    the entirety of the wetted path of said Coriolis flowmeter comprises said PFA material;    a driver coupled to said single flow tube for vibrating said single flow tube containing said process material;    a massive base coupled by upwardly extending walls to ends of said single flow tube to absorb undesired vibratory forces generated by said vibrating flow tube;    said base defines stationary nodes proximate opposing ends of said flow tube;    an inlet connector connected to said massive base and adapted to receive a flow of said process material from a supply tube;    an inlet end of said single flow tube is affixed to said inlet connector;    said input connector sealably connects said inlet end of said single flow tube to an outlet end of said supply tube to effect the extension of said process material flow in said supply tube to said single flow tube;    said inlet connector maintains said inlet end of said flow tube fixed with respect to said massive base;    an outlet end of said single flow tube affixed to a second connector for extending said process material flow via an exit tube towards a user destination;    a pair of pickoffs coupled to said single flow tube on opposite axial sides of said driver for generating signals representing Coriolis induced deflections of said vibrating material filled single flow tube;    meter electronics; and    conductors extending signals from said pickoffs to said meter electronics;    said meter electronics receives said pickoff output signals and generates output information pertaining to said process material flow.    
     
     
         12 . The Coriolis flowmeter of  claim 11  further comprising; 
 a return tube connected to said massive base parallel to said single flow tube;    end portions of said single flow tube and said return tube are glued to said massive base to maintain said single flow tube and said return tube immovable with respect to said massive base;    an inlet of said return tube;    an intermediate tube connecting said outlet end of said single flow tube and said inlet end of said return tube via said second connector to extend said process material flow from said outlet end of said single flow tube to said inlet of said return tube;    an outlet connector connected to said massive base for receiving said flow of said process material from said outlet end of said return tube;    said outlet connector sealably connects said outlet end of said return tube to an inlet end of an exit tube to effect the extension of said process material flow in said return tube to said exit tube;    said exit tube is adapted to extend said process material flow to a user destination.    
     
     
         13 . The Coriolis flowmeter of  claim 1  characterized in that said flow tube apparatus has high flexibility and a stiffness substantially lower than flow tube apparatus formed of metal or glass.  
     
     
         14 . The Coriolis flowmeter of  claim 1  characterized in that said flow tube apparatus has walls substantially thinner than the diameter of the inner portion of the flow tube apparatus through which said material flows.  
     
     
         15 . The Coriolis flowmeter of  claim 11  characterized in that said single flow tube is substantially straight.  
     
     
         16 . The Coriolis flowmeter of  claim 1  characterized in that said flow tube apparatus comprises a single flow tube and that said base is substantially U-shaped and has a mass substantially greater than the mass of said flow tube with process material.  
     
     
         17 . The Coriolis flowmeter of  claim 1  characterized in that said flow tube apparatus has: 
 a drive frequency deflection that extends over the entirety of the axial length of the active portion of said flow tube apparatus;    and further has a Coriolis deflection that extends over the entirety of the axial length of the active portion of said flow tube apparatus.    
     
     
         18 . The Coriolis flowmeter of  claim 1  characterized in that said base is massive and said flow tube apparatus comprises a single flow tube connected to said massive base to define a dynamically balanced structure when vibrated with material flow by said driver.  
     
     
         19 . The Coriolis flowmeter of  claim 1  characterized in that: 
 said flow tube apparatus comprises a single flow tube defining a dynamically unbalanced structure; and    said base has a mass sufficiency large to vibrationally communicate with said flow tube so that said Coriolis flowmeter defines a dynamically balanced structure when in use.    
     
     
         20 . The Coriolis flowmeter of  claim 1  characterized in that said flow tube apparatus comprises at least one flow tube having a substantially constant outer diameter.