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Class Information
Number: 137/412
Name: Fluid handling > Liquid level responsive or maintaining systems > By float controlled valve > Servo relay operation of control
Description: Apparatus in which the float controls the application of another source of power for operating the flow controlling means rather than acting directly through a mechanical connection.

Sub-classes under this class:

Class Number Class Name Patents
137/413 Fluid pressure 98

Patents under this class:
1 2

Patent Number Title Of Patent Date Issued
8622079 Method for extending the usage life of oil in a deep fat fryer Jan. 7, 2014
8220482 Devices, methods, and algorithms for rapid measurement of mean surface level change of liquids in containers Jul. 17, 2012
8132589 Regulating valve for the discharge of liquid Mar. 13, 2012
7891373 Flow control valve Feb. 22, 2011
7000627 Toilet safety valve Feb. 21, 2006
6629627 Level control systems for high purity chemical delivery systems Oct. 7, 2003
6591860 Infinitely adjustable, low deadband, point contact pneumatic level switch Jul. 15, 2003
6453939 Flotation cell fluid level control apparatus Sep. 24, 2002
6431201 Wet battery and vehicle-based water management system Aug. 13, 2002
6082394 Closed type water storage container with water level controller and air filtering device Jul. 4, 2000
5967175 Waste line stoppage detector and automatic water shutoff system Oct. 19, 1999
5704389 Waste line stoppage detector and automatic water shutoff system Jan. 6, 1998
5660334 Remote control for electrostatic sprayer elements Aug. 26, 1997
5607002 Chemical refill system for high purity chemicals Mar. 4, 1997
5542499 Electromechanical oil level regulator Aug. 6, 1996
5515883 Waste line stoppage detector and automatic water shutoff system May. 14, 1996
5465766 Chemical refill system for high purity chemicals Nov. 14, 1995
5435145 Refrigerant flow rate control based on liquid level in simple vapor compression refrigeration cycles Jul. 25, 1995
5365969 Float with skirt to prevent leakage due to oversudsing Nov. 22, 1994
5339854 Conservation system and method Aug. 23, 1994
5309939 Safety device for water-conducting household appliances May. 10, 1994
5290402 Automatic cold/hot distilled water fountain Mar. 1, 1994
5209254 Water and sewerage system for construction, and protection for the same May. 11, 1993
5072600 Wash column ice-pack bottom detection device Dec. 17, 1991
5018550 Dishwasher overfill protection device May. 28, 1991
4994211 Water distribution apparatus for evaporative cooling system Feb. 19, 1991
4940861 Liquid shut-off system Jul. 10, 1990
4936389 Fluid dispenser for an aircraft Jun. 26, 1990
4904830 Liquid shut-off system Feb. 27, 1990
4865073 Liquid level control for refrigeration system Sep. 12, 1989
4856288 Refrigerant alert and automatic recharging device Aug. 15, 1989
4771804 Liquid level sensing and control assembly Sep. 20, 1988
4744808 Liquid level sensing and control May. 17, 1988
4700738 Liquid level controller Oct. 20, 1987
4688699 Bactericidal mixture control system having flow and dispense duration controls for respective substances Aug. 25, 1987
4687031 Valve control with mechanical memory Aug. 18, 1987
4655244 Float operated valve Apr. 7, 1987
4649898 Apparatus for controlling condensate level in steam retort Mar. 17, 1987
4637425 Sewer check valve with cutting seat Jan. 20, 1987
4607399 Automatic pool water regulator apparatus Aug. 26, 1986
4597048 Digital flow regulation of liquid-level control for a continuous casting mold Jun. 24, 1986
4365489 Cleaning liquid level regulator for dry cleaning machines Dec. 28, 1982
4336825 Liquid level control system Jun. 29, 1982
4313566 Fluid balancing system for tank vehicle Feb. 2, 1982
4271861 Dishwasher fill level control arrangement Jun. 9, 1981
4259975 Stock tank gauger-level controller Apr. 7, 1981
4180095 Dishwasher float switch control assembly Dec. 25, 1979
4178957 Dishwasher fill system Dec. 18, 1979
4121618 Hydraulic ramping circuit for control valve Oct. 24, 1978
3966437 High pressure gas-liquid separator Jun. 29, 1976

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