US 6,606,905 B2Granted

Liquid level and weight sensor

AssigneeNorthrop Grumman Corporation

InventorsCarlton W. Carroll, A. David Klein

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Abstract

A liquid level and weight sensor utilizes a pressure sensor of any type positioned at the base of the liquid or weight. A second pressure sensor is positioned external to the liquid or weight to measure the ambient pressure. Ambient pressure is subtracted from the total pressure indicated by the base positioned pressure sensor to determine the actual pressure exerted by the liquid or weight on the base positioned sensor. The actual pressure is then utilized in the calculation of liquid level or weight. The determination of liquid level requires that both the pressure and density of the liquid be known. When the density of the liquid is not known, a third pressure sensor is inserted in the tank at a known level above the first. The differential pressure and differential level are determinative of the liquid's density.

Claims7

Dependent claims

An apparatus for sensing a level of a liquid, the liquid having a density, a liquid base, and a liquid surface, the level being the height of the liquid surface above the liquid base, comprising:

at least one base pressure sensor positioned at said base, whereby pressure at said base due to said height of said liquid is determined;
at least one external pressure sensor positioned above said liquid surface, whereby pressure external to said liquid surface is determined;
a level indicator coupled to said base pressure sensor and said external pressure sensor wherein said level of said liquid is determined from pressure values provided by said at least one base pressure sensor and said at least one external pressure sensor;
and
at least one intermediate sensor coupled to said level indicator and positioned below said surface at a predetermined height above said at least one base sensor, said level indicator utilizing pressure values provided by said at least one base pressure sensor and said at least one intermediate pressure sensor to determine said density of said liquid.

2 more elements

A method for sensing a level of a liquid, the liquid having a density, a liquid base, and a liquid surface, the level being the height of the liquid surface above the liquid base, comprising the steps of:

positioning at least one base pressure sensor at said base, whereby pressure at said base due said height of said liquid is determined;
locating at least one external pressure sensor above said liquid surface, whereby pressure external to said liquid surface is determined;
coupling said base pressure sensor and said external pressure sensor to a level indicator wherein said level of said liquid is determined from pressure values provided by said at least one base pressure sensor and said at least one external pressure sensor;
positioning at least one intermediate pressure sensor below said surface at a predetermined height above said at least one base sensor;
coupling said at least one intermediate pressure sensor to said level indicator;
and
determining liquid density from pressure values provided by said at least one base pressure sensor and said at least one intermediate pressure sensor.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/930,653Filed 15 Aug 2001
Published: US 2003/0033871 A120 Feb 2003
Granted: 19 Aug 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01G 3/12
Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances: wherein the weighing element is in the form…
G01F 23/14
Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm: by…
G01G 17/04
Apparatus for or methods of weighing material of special form or property: for weighing fluids, e.g. gases, pastes
G01G
Weighing