A tank and liquid level indicator has first housing that holds a liquid and a second elongated housing in fluid communication with the first elongated housing so that a liquid level in the second housing is approximately equal to the level in the first housing. A float in the second housing cooperates with the circuitry to operate one or more light switches. A light-transmissive cover is disposed over the light source.

An improved fluid level verification apparatus with an integral, internal source of illumination that is powered by an integral, internal energy source and is activated by a motion sensor or any other sensor commonly known In the art to detect the presence of a person in dark or dimly lit environments. The preferred light source is a light emitting diode (LED). A second embodiment of the integral, internal source of illumination that is powered by an integral, internal energy source and is activated by a motion sensor or any other sensor commonly known in the art to detect the presence of a person in dark or dimly lit environments is applied to a fluid reservoir tank.

A pressure sensor that includes a housing with an upper housing part and a lower housing part, the upper housing part and the lower housing part being configured such that a chamber is formed between them. A diaphragm is provided between the upper housing part and the lower housing part, and dividing the chamber into an upper chamber and a lower chamber. A magnetic core is linked to the diaphragm. An operating spring includes a top end and a bottom end, the top end being supported against the upper housing part and the bottom end being supported against the magnetic core. At least one of the top end and the bottom end of the operating spring is provided with an adhesive layer. The pressure sensor enables the operating spring and the magnetic core to move integrally with each other, thereby improving the precision of the pressure sensor.

A tank and liquid level indicator has first housing that holds a liquid and a second elongated housing in fluid communication with the first elongated housing so that a liquid level in the second housing is approximately equal to the level in the first housing. A float in the second housing cooperates with the circuitry to operate one or more light switches. A light-transmissive cover is disposed over the light source.

A liquid level detection device is disposed in a container having a viscous liquid. The liquid level detection device includes an installing seat, a connecting rod, a pivoting structure connecting the installing seat and one end of the connecting rod, and a floating element disposed at one end of the connecting rod opposite to the installing seat. Further, the liquid level detection device includes a protecting bladder disposed to correspond to the pivoting structure. The protecting bladder divides the liquid level detection device into a coated part and an exposed part. One end of the floating element opposite to the installing seat is the exposed part. The protecting bladder isolates the viscous liquid from contacting with the pivoting structure to prevent excessive viscous liquid from remaining on the pivoting structure and avoid the problem of misoperation of the liquid level detection device caused by the influence of the protecting bladder.

A fluid evaluation device for analyzing a fluid content within a container includes first and second fluid sampling conduits passing laterally into the container and respectively extending to first and second depths within fluid stored in the container, a common fluid conduit to which the first and second fluid sampling conduits extend for receiving fluid flowing out of the container through either of the first or second sampling conduits, and an optical device positioned along the common fluid conduit and including a viewing window for observing fluid flowing therethrough from the common fluid conduit.

A fluid evaluation device for analyzing a fluid content within a container includes first and second fluid sampling conduits passing laterally into the container and respectively extending to first and second depths within fluid stored in the container, a common fluid conduit to which the first and second fluid sampling conduits extend for receiving fluid flowing out of the container through either of the first or second sampling conduits, and an optical device positioned along the common fluid conduit and including a viewing window for observing fluid flowing therethrough from the common fluid conduit.

A chemical tank level system for a wellbore chemical injection tank is provided. The system includes a pressure sensor is located downstream of the chemical injection tank where the fluidic pressure is essentially the same as the fluidic pressure at the base of the chemical tank. The pressure sensor sends a signal indicative of the fluidic pressure to a tank level sensor module. The tank level sensor module receives the signal from the pressure sensor. A processor takes a series of pressure sensor signals over a sample window and calculates an average of the signals over a defined time window.

An improved fluid level verification apparatus with an integral, internal source of illumination that is powered by an integral, internal energy source and is activated by a motion sensor or any other sensor commonly known in the art to detect the presence of a person in dark or dimly lit environments. The preferred light source is a light emitting diode (LED). A second embodiment of the integral, internal source of illumination that is powered by an integral, internal energy source and is activated by a motion sensor or any other sensor commonly known in the art to detect the presence of a person in dark or dimly lit environments is applied to a fluid reservoir tank.

Methods and systems are providing for improving engine coolant level estimation to reduce engine overheating. The level of fluid in a coolant overflow reservoir is inferred based on the fluid level in a hollow vertical standpipe fluidically coupled to the reservoir at top and bottom locations, while the fluid level in the standpipe is estimated based on echo times of an ultrasonic signal transmitted by a sensor positioned in a recess at the bottom of the vertical standpipe. Engine power is limited differently based on distinct coolant level states determined based on a change in level of coolant in the reservoir over a duration.