In-line viscometer

Claim 1

An in-line viscometer installed in a parallel relationship in a main stream flowsection which is to contain a viscous fluid which is to be pumped at a measured flow while the viscosity is to be determined by said in-line viscometer which is subjected to the same temperature and pressure that said main stream flowsection is subjected to while viscosity is being determined of said viscous fluid, said in-line viscometer comprising (i) a friction flow tube sized to a predetermined size so that viscous fluid flow through said friction flow tube is laminar and so that impact pressure from said viscous fluid flow forces said viscous fluid through said friction flow tube; (ii) an entrance end pressure port and exit end pressure port at respective ends of said friction flow tube; (iii) means for measuring viscous flow rate through said main stream flowsection; and, (iv) means for measuring pressure at said entrance end pressure port and said exit end pressure port to establish the diferential pressure between said entrance end pressure port and said exit end pressure port whereby the viscosity of said viscous fluid is determined from the equation: ##EQU8## wherein μ is viscosity, P 2 is entrance port pressure of said viscous fluid, P 1 is exit port pressure of said viscous fluid, K C is a calibration constant, ρ is fluid density, A is cross sectional area of said main stream flowsection, and Q T is flow rate in said main stream flowsection.