# US 7,073,372 B2 · Online rotating viscometer and associated measurement methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,073,372 B2 - Document ID: US7073372B2 - Status: Granted - Kind: B2 - Application number: 10/478,029 - Filed: 2002-05-17 - Published: 2004-09-16 - Granted: 2006-07-11 - Earliest claimed: 2001-05-18 - Assignees: MLD Research - Inventors: Hugues Lahaut - Web page: https://patentgrep.com/patent/US7073372B2 ## CPC - G01N 11/14: by using rotary bodies, e.g. vane (G01N11/16 takes precedence) - G01N 2203/0025: Shearing - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract Rotating type viscosimeter having a motor (2) for driving a rotating assembly (3) extending through an aperture (4) into a liquid to be tested (1) and measuring the shear forces imparted by said liquid (1) to the rotating assembly (3). In order to prevent said liquid (1) from leaking through the aperture (4) due to a liquid pressure (p1) at the level of the aperture (4), the viscosimeter comprises means for creating a counter-pressure (p2) at the level of a gap between the rotating assembly (3) and the aperture (4). Thanks to this counter-pressure (p2), no solid sealing means are required, thereby improving the durability and the robustness of the viscosimeter, as well as simplifying it by eliminating countermeasures otherwise needed for taking into account parasitic friction forces exerted on the rotating assembly (3) due to such solid sealing means. ## Claims ### Claim 1 Viscosimeter comprising a motor (2) for driving an assembly (3) in a rotary movement, said assembly (3) extending at least partially into a liquid to be tested (1) through an aperture (4) of a partition (5) for separating the liquid (1) from the motor (2), characterized in that the viscosimeter comprises means for creating a counter-pressure (p2) at a motor side (M) of the partition (5) for preventing the liquid (1) from escaping through the aperture (4), the level of the liquid (1) being—in operation—above the aperture (4). ### Claim 2 (depends on 1) Viscosimeter according to claim 1, further comprising means (40) for regulating the counter-pressure (p2). ### Claim 3 (depends on 2) Viscosimeter according to claim 2, characterized in that a gap between the rotating assembly (3) and the aperture (4) at the level of the aperture (4) is greater than or equal to 0.01 mm and less than or equal to 5 mm. ### Claim 4 (depends on 3) Viscosimeter according to claim 3, characterized in that the gap is greater than or equal to 0.1 mm and less than or equal to 1 mm. ### Claim 5 (depends on 4) Viscosimeter according to claim 4, further comprising automatic sealing means for preventing the liquid (1) from escaping through the aperture (4) in case the means for creating the counter-pressure (p2) at the motor side (M) of the partition (5) fail to prevent the liquid (1) from escaping through the aperture (4). ### Claim 6 (depends on 5) Viscosimeter according to claim 5, characterized in that the automatic sealing means comprise a safety membrane (70) hermetically attached to the rotating assembly (3) and in that the apparent surface of said safety membrane (70) overlaps the aperture (4). ### Claim 7 (depends on 6) Viscosimeter according to claim 6, characterized in that a medium for exerting the counter-pressure (p2) is ambient air. ### Claim 8 (depends on 6) Viscosimeter according to claim 6, characterized in that a medium for exerting the counter-pressure (p2) is an inert gas. ### Claim 9 (depends on 1) Viscosimeter according to claim 1, characterized in that a gap between the rotating assembly (3) and the aperture (4) at the level of the aperture (4) is greater than or equal to 0.01 mm and less than or equal to 5 mm. ### Claim 10 (depends on 9) Viscosimeter according to claim 9 characterized in that the gap is greater than or equal to 0.1 mm and less than or equal to 1 mm. ### Claim 11 (depends on 1) Viscosimeter according to claim 1, further comprising automatic sealing means for preventing the liquid (1) from escaping through the aperture (4) in case the means for creating the counter-pressure (p2) at the motor side (M) of the partition (5) fail to prevent the liquid (1) from escaping through the aperture (4). ### Claim 12 (depends on 11) Viscosimeter according to claim 11, characterized in that the automatic sealing means comprise a safety membrane (70) hermetically attached to the rotating assembly (3) and in that the apparent surface of said safety membrane (70) overlaps the aperture (4). ### Claim 13 (depends on 1) Viscosimeter according to claim 1, characterized in that a medium for exerting the counter-pressure (p2) is ambient air. ### Claim 14 (depends on 3) Viscosimeter according to claim 3, characterized in that a medium for exerting the counter-pressure (p2) is ambient air. ### Claim 15 (depends on 4) Viscosimeter according to claim 4, characterized in that a medium for exerting the counter-pressure (p2) is ambient air. ### Claim 16 (depends on 5) Viscosimeter according to claim 5, characterized in that a medium for exerting the counter-pressure (p2) is ambient air. ### Claim 17 (depends on 1) Viscosimeter according to claim 1, characterized in that a medium for exerting the counter-pressure (p2) is an inert gas. ### Claim 18 (depends on 3) Viscosimeter according to claim 3, characterized in that a medium for exerting the counter-pressure (p2) is an inert gas. ### Claim 19 Method for measuring the viscosity of a liquid to be tested (1), comprising the steps of: having a motor (2) driving an assembly (3) in a rotary movement, said assembly (3) extending at least partially into the liquid to be tested (1) through an aperture (4) of a partition (5) for separating the liquid (1) from the motor (2), the level of the liquid (1) being—in operation—above the aperture (4), creating a counter-pressure (p2) at a motor side (M) of the partition (5) for preventing the liquid (1) from escaping through the aperture (4), and measuring the shear forces imparted by the liquid (1) on a part of the rotating assembly (3) in contact with the liquid (1). ### Claim 20 (depends on 19) Method for measuring the viscosity of a liquid according to claim 19, further comprising the step of regulating the counter-pressure (p2).