A METHOD AND APPARATUS FOR FLUID DENSITY SENSING
Methods and apparatus for measuring density of a fluid. The apparatus includes a shaft adapted to be positioned within a fluid and a biased float disposed on the shaft and capable of movement along the shaft. The apparatus further includes a displacement sensor for detecting a position of the float along the shaft. A method of sensing the density includes positioning the biased float in the fluid and sensing the position of the float to obtain data representative of the density of the fluid.
1 . An apparatus for sensing the density of a fluid comprising:
a shaft adapted to be positioned in a fluid;
a biased float disposed on said shaft and capable of movement along said shaft; and
a displacement sensor for detecting a position of said float along said shaft,
wherein said apparatus is configured to sense the density of the fluid based on the position of said float.
2 . The apparatus of claim 1 , wherein said biased float further comprises:
a mounting plate secured to said shaft; and
a spring having a first end adapted to engage the mounting plate and a second end adapted to engage the float.
3 . The apparatus of claim 2 , wherein said spring is positioned so as to operate as a compression spring.
4 . The apparatus of claim 2 , wherein said spring is positioned so as to operate as an extension spring.
5 . The apparatus of claim 1 , wherein a density of said float is less than a density of the fluid so that a buoyant force acts on said float in a direction opposite to gravity.
6 . The apparatus of claim 1 , wherein a density of said float is different from a density of the fluid so that a buoyant force acts on said float in a first direction, and wherein said float is biased so as to resist movement in the first direction.
7 . The apparatus of claim 1 , wherein said displacement sensor is a magnetostrictive sensor.
8 . An apparatus for sensing the density of a fluid comprising:
a shaft adapted to be positioned in a fluid within a container;
a first float assembly disposed on said shaft, said first float assembly comprising:
a mounting plate adapted to be secured to said shaft;
a spring having first and second ends, the first end adapted to engage said mounting plate; and
a float adapted to engage the second end of said spring and capable of movement along said shaft; and
a displacement sensor comprising:
a magnetostrictive waveguide disposed along said shaft;
a magnet operatively coupled to said float for movement therewith and in operative relation to said magnetostrictive waveguide; and
pulsing and detection apparatus for detecting a position of said magnet along said magnetostrictive waveguide,
wherein said apparatus is configured to sense the density of the fluid based on the position of the float.
9 . The apparatus of claim 8 , wherein said mounting plate and said spring are positioned so that said float compresses said spring.
10 . The apparatus of claim 8 , wherein said mounting plate and said spring are positioned so that said float extends said spring.
11 . The apparatus of claim 8 , wherein a density of said float is different from a density of the fluid so that a buoyant force acts on said float in a first direction, and wherein said float is biased by said spring so as to resist movement in the first direction.
12 . The apparatus of claim 8 , further comprising:
a first product float movably disposed on said shaft and configured to sense the level of the fluid in the container.
13 . The apparatus of claim 12 , wherein said first product float includes a magnet operatively coupled thereto for movement therewith and in operative relation to said magnetostrictive waveguide, said magnet cooperating with said displacement sensor to determine the position of said first product float along said magnetostrictive waveguide.
14 . The apparatus of claim 8 , further comprising:
a first product float movably disposed on said shaft and configured to sense the level of a first fluid in the container; and
a second product float movably disposed on said shaft and configured to sense the level of a second fluid in the container.
15 . The apparatus of claim 14 , wherein said first and second product floats each include a magnet operatively coupled thereto for movement therewith and in operative relation to said magnetostrictive waveguide, each of said magnets cooperating with said displacement sensor to determine the position of said first and second product floats along said magnetostrictive waveguide.
16 . The apparatus of claim 8 , further comprising:
a second float assembly disposed on said shaft and spaced apart from said first float assembly.
17 . The apparatus of claim 8 , wherein said mounting plate includes a magnet operatively coupled thereto and in operative relation to said magnetostrictive waveguide, said magnet in said mounting plate cooperating with said displacement sensor to determine the position of said mounting plate along said magnetostrictive waveguide.
18 . The apparatus of claim 8 , further comprising:
a constraint plate disposed on said shaft and spaced from said mounting plate so that said float is disposed therebetween.
19 . A density sensor kit for retrofitting a product level probe so as to be able to sense the density of a fluid in a container, the probe including a shaft adapted to be positioned in the fluid within the container, a product float movably disposed on the shaft, and a displacement sensor including a magnetostrictive waveguide disposed along the shaft, and pulsing and detection apparatus for detecting a position of a magnet along the magnetostrictive waveguide, the kit comprising:
a first float assembly adapted to be disposed on the shaft, comprising:
a mounting plate adapted to be secured to the shaft;
a spring having first and second ends, the first end adapted to engage said mounting plate; and
a float adapted to engage the second end of said spring and capable of movement along the shaft when coupled thereto; and
a magnet adapted to be coupled to said float,
wherein said first float assembly is configured to sense the density of the fluid based on the position of the float.
20 . The kit of claim 19 , further comprising:
a magnet adapted to be operatively coupled to said mounting plate.
21 . The kit of claim 19 , further comprising:
a constraint plate adapted to be disposed on the shaft and spaced from said mounting plate so that said float is disposed therebetween.
22 . A method of sensing the density of a fluid comprising:
positioning a float within the fluid wherein said float has a buoyancy with respect to the fluid;
biasing the float against its buoyancy in the fluid; and
sensing the position of the float to obtain data representative of the density of the fluid.
23 . The method of claim 22 , wherein sensing the movement of the float further comprises:
sensing the movement magnetostrictively by causing relative movement of one of a magnetostrictive waveguide and a magnet operatively disposed proximate the magnetostrictive waveguide upon movement of the float.
24 . A method of monitoring a fluid within a container comprising:
sensing the level of the fluid in the container using a sensor; and
sensing the density of the fluid in the container using the same sensor.
25 . The method of claim 24 , wherein sensing the level of the fluid and sensing the density of the fluid is done magnetostrictively.
26 . A fluid density-sensing apparatus comprising:
an elongated displacement sensor extending into a fluid;
a float in said fluid operatively movable with respect to the displacement sensor; and
calculating apparatus for signaling fluid density as a function of the position of said float with respect to said displacement sensor.
27 . The apparatus of claim 26 , wherein said displacement sensor is a magnetostrictive sensor.
28 . The apparatus of claim 26 , further comprising:
biasing apparatus for biasing the float against its buoyancy in the fluid.
29 . The apparatus of claim 28 , further comprising:
apparatus securing said biasing apparatus to said elongated displacement sensor.