Universal single point liquid level sensor

Patent Application · Tue May 02 00:00:00 EDT 1989

OSTI ID:6721819

Kronberg, J W

A liquid level detector comprises a thermistor and circuitry for determining electrically if the thermistor is wet or dry and additionally, and continuously, if the thermistor is open or shorted. The voltage across the thermistor is filtered to remove low frequency electrical noise, then compared with a reference low voltage to determine if shorted and to a transition voltage chosen to be between the thermistor's nominal wet and dry voltages to determine if the thermistor is wet or dry. The voltage is also compared to the supply voltage using a CMOS gate circuit element to determine if the thermistor is open. The gate passes both faults on to an LED to signal that a fault condition exists or indicates by another LED the wet or dry condition of the thermistor. A pump may be activated through a relay if the thermistor tests wet or dry, as desired. 1 fig.

• Research Organization: Du Pont de Nemours (E.I.) and Co., Aiken, SC (USA). Savannah River Plant
• Sponsoring Organization: DOE/DP
• DOE Contract Number: AC09-76SR00001
• Assignee: Dept. of Energy
• Patent Number(s): PATENTS-US-A7346490
• Application Number: ON: DE90014576; PPN: US 7-346490
• OSTI ID: 6721819
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION
42 ENGINEERING
LEVEL INDICATORS
DESIGN
LEVELS
CONTROL
LIQUIDS
AUTOMATION
CORROSION RESISTANCE
HEAT TRANSFER
PROCESS CONTROL
PUMPS
RADIOACTIVE MATERIALS
THERMISTORS
ENERGY TRANSFER
FLUIDS
MATERIALS
MEASURING INSTRUMENTS
SEMICONDUCTOR DEVICES
440800* - Miscellaneous Instrumentation- (1990-)
426000 - Engineering- Components
Electron Devices & Circuits- (1990-)