A level indicator with a cover that measures a water level, includes: a water level indicator that measures pressure; and a protective cover that surrounds the water level indicator. The protective cover includes a pressure transmitter that transmits pressure on an outside of the protective cover to an inside of the protective cover.

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.

According to one aspect, a lubricant level sensing system for an actuator is provided. The lubricant level sensing system includes a pressure port in an outer housing of the actuator, a pressure sensor, and a pathway from the pressure port to the pressure sensor. The pathway establishes fluid communication between the pressure sensor and a free volume of an internal cavity of the outer housing relative to a lubricant level in the internal cavity such that the pressure sensor detects a pressure of the free volume used to derive the lubricant level.

A vessel with a cavity for measuring level is disclosed. The vessel includes a differential pressure sensor having a first port and a second port, a reference tube that connects the first port of the differential pressure sensor to a bottom portion of the cavity, and an impulse tube that connects the second port of the differential pressure sensor to an impulse tube ending. At least a portion of the impulse tube extends through the cavity and ends at a fluid inlet. The fluid inlet is located at a level above the reference tube.

A fluid level measurement system, including an instrument line configured for installation within a fluid storage tank or vessel, the instrument line having a first end configured to be installed below a fluid level of the storage tank and a second end configured to be installed above the fluid level of the storage tank, the first end including a first pressure diaphragm plate configured to communicate with fluid within the storage tank, a pressure sensor configured to be connected to the second end of the instrument line, and a relief valve configured to open and allow high-pressure gas in the tank to escape through a ventilation port in order to depressurize the tank until tank pressure equalizes with the surrounding atmospheric pressure.

A wireless pressure sensor for sensing pressure of a liquid in a tank includes a hermetically sealed housing, at least one sensor, at least one photocell array, at least one communication device, and at least one energy storage device. At least a portion of the hermetically sealed housing has a diaphragm. The at least one sensor within the hermetically sealed housing is configured to sense the pressure of the liquid. The at least one photocell array is configured to receive light and generate power from the light. The at least one communication device is configured to transmit data corresponding to the sensed pressure using wireless radio frequency signals. The at least one energy storage device is configured to store power generated by the at least one photocell array and provide power to the at least one sensor and the at least one communication device.

An optically powered pressure sensor for sensing pressure of a liquid in a tank includes a hermetically sealed housing with at least a portion of the housing having a diaphragm, at least one sensor within the hermetically sealed housing, at least one optical emitter, and a photocell array. The hermetically sealed housing forms at least a portion of a hermetically sealed wall of the tank. The at least one sensor within the hermetically sealed housing is configured to sense the pressure of the liquid. The at least one optical emitter is configured to transmit data corresponding to the sensed pressure. The photocell array is configured to receive light and provide power to the at least one sensor and the at least one optical emitter.

Pressure sensor systems for measuring a liquid pressure and deriving a liquid level from the measured pressure using gas pressure sensing devices. In one embodiment, liquid pressure results in compression or decompression of a trapped gas (as an example, air), wherein the gas pressure is detected by a gas pressure sensing device directly or a gas pressure sensing device that is protected inside a flexible pouch filled with a liquid. In another embodiment, a gas pressure sensing device is packaged in a flexible pouch filled with an inert liquid to protect the sensing device and circuit thereof from external contaminants while accurately transferring pressure from the liquid through a protective barrier. Application of such sensors in a wireless flood or a wireless liquid level measurement system is described as well.

According to one aspect, a lubricant level sensing system for an actuator is provided. The lubricant level sensing system includes a pressure port in an outer housing of the actuator, a pressure sensor, and a pathway from the pressure port to the pressure sensor. The pathway establishes fluid communication between the pressure sensor and a free volume of an internal cavity of the outer housing relative to a lubricant level in the internal cavity such that the pressure sensor detects a pressure of the free volume used to derive the lubricant level.

An example system includes a fuel tank, fittings mounted through a wall of the fuel tank, and optical sensors positioned within the fittings. A respective optical sensor includes a first pressure sensing end inserted through a fitting and internally into the fuel tank and a second end extending externally from the fuel tank. The system also includes an optical fiber bundle mounted external to the fuel tank, and having an optical fiber connected to each of the plurality of optical sensors for guiding light to each of the plurality of optical sensors.