Donald Cletus Reed

US Patent:

49055054, Mar 6, 1990

Filed:

Mar 3, 1989

Appl. No.:

7/318381

Inventors:

Donald B. Reed - Plano TX

Assignee:

Atlantic Richfield Company - Los Angeles CA

International Classification:

G01N 700

US Classification:

73 642

Abstract:

The vapor pressure of a multi-component liquid composition is measured by providing an eductor through which the liquid composition is caused to flow at selected inlet pressures to provide incrementally changing pressure differentials across the eductor. The pressure differential is read for each incremental change across the eductor and the suction port pressure is read at each incremental pressure differential until the suction port pressure as a function of the pressure differential indicates a change in slope or point of inflection along the so-called dead fluid curve indicating the bubble point or true vapor pressure of the liquid composition. A motorized pressure regulator valve may be interposed in the liquid composition flow conduit upstream of the eductor for incrementally changing the pressure differential. The point of inflection may be obtained by determining the mathematical relationship using the cubic spline fit technique and calculating the second derivative of the function of the suction port pressure versus the pressure differential across the eductor until the second derivative equals zero.

US Patent:

51725860, Dec 22, 1992

Filed:

Oct 26, 1990

Appl. No.:

7/604717

Inventors:

Donald B. Reed - Plano TX

Assignee:

Atlantic Richfield Company - Los Angeles CA

International Classification:

G01N 714

US Classification:

73 6445

Abstract:

True vapor pressure of liquid compositions, particularly multi-component compositions, is measured by a piston and cylinder apparatus defining an expansible chamber in which a simple of liquid is trapped, the chamber is expanded in multiple steps and multiple pressure and temperature measurements are taken at each expansion over a period of time. A resultant pressure at each expansion is determined from multiple measurements using the least squares method of approximation and the plural resultant pressure values are extrapolated to determine true vapor pressure using a straight-line approximation. The apparatus is adapted to continuously measure vapor pressure of a process stream by sampling a slipstream of liquid which is maintained at a constant temperature. The apparatus cylinder includes a bore which is closed at one end by a pressure transducer defining an end wall of the measurement chamber. The apparatus is mounted horizontally to minimize liquid depth and increase the rate of bubble formation during expansion of the chamber.

US Patent:

47839899, Nov 15, 1988

Filed:

Mar 5, 1987

Appl. No.:

7/022155

Inventors:

Donald B. Reed - Plano TX

Assignee:

Atlantic Richfield Company - Los Angeles CA

International Classification:

G01N 714

US Classification:

73 642

Abstract:

Vapor pressure of liquid compositions is measured by a system having a cylinder member in which a reciprocal piston is disposed for movement to contain a sample of liquid and expand the chamber while measuring the pressure in the chamber until a substantially constant pressure is reached with increasing chamber volume. Liquid is circulated from a source such as a petroleum pipeline to the apparatus and continually through the expansible chamber in a retracted position of the piston. When a sample vapor pressure measurement is to be taken, the piston closes off a passage leading to the chamber and displaces liquid out of the chamber until a minimum volume is reached. The movement of the piston is then reversed to increase chamber volume while monitoring pressure and temperature to detect the onset of cavitation. Different samples of the same liquid may be taken while permitting the maximum volume of the chamber to vary with each sample so that a plot of maximum or equilibrium pressures can be obtained as a function of chamber size whereby extrapolation may be used to determine true vapor pressure of the composition.