A liquid surface detector includes an electrode pad, a coil, a memory, and a detection control circuit. The electrode pad is attached to an outer side surface of a tank of the image forming apparatus. The coil is connected to the electrode pad. The memory stores initial values. The detection control circuit determines a capacitance (first capacitance) of a first resonance circuit including the coil and the tank with the electrode pad. When determining a liquid surface level value, the detection control circuit subtracts an error value from the first capacitance so as to determine a first corrected capacitance, and determines the liquid surface level value based on the first corrected capacitance and the initial value.

A guided wave level gauge which processes reflections from impedance transitions seen along a probe connected to the gauge. Determines the level based on reflections received from a surface of the material, end of the probe, a connection of the probe to the gauge, and a relative velocity (Vr) of propagation of the electromagnetic signal for the portion of the probe above the material surface to the portion of the probe below the surface. Determines the level without a surface reflection based on the end of probe reflection, probe to gauge connection reflection, relative velocity Vr, and an electrical length of the probe. The methods include determining the relative velocity Vr and the electrical length of the probe. The apparatus includes placing the probe on the outside surface of the tank. The apparatus includes jacketing the probe to improve the reflection received from the end of the probe.

A fluid processing system may include a flow control cassette comprising at least one interface sensor chamber in fluid communication with at least one of a plurality of separate channels, the at least one interface sensor chamber defined at least in part by a wall, and at least one capacitive sensor disposed on the wall of the at least one interface sensor chamber. The fluid processing system may include, in the alternative or in addition, at least one syringe comprising a wall defining a barrel having a first end and a second end, the barrel having a bore with or without a piston or plunger disposed therein, and at least one capacitive sensor disposed on an outer surface of the wall of the syringe.

A fluid processing system may include a flow control cassette comprising at least one interface sensor chamber in fluid communication with at least one of a plurality of separate channels, the at least one interface sensor chamber defined at least in part by a wall, and at least one capacitive sensor disposed on the wall of the at least one interface sensor chamber. The fluid processing system may include, in the alternative or in addition, at least one syringe comprising a wall defining a barrel having a first end and a second end, the barrel having a bore with or without a piston or plunger disposed therein, and at least one capacitive sensor disposed on an outer surface of the wall of the syringe.

A sensor system is described that can be attached to the outside wall of a nonmetallic container located within an outer cage, and that measures with high resolution a level of liquid inside the container using capacitance changes at the sensor system. The sensor system includes a sensing element having a metal channel that houses a foam ribbon, and a conductive strip is applied to the foam ribbon oppositely from the metal channel to form a capacitor. Sensor electronics can determine capacitance changes from which the liquid level is determined, and can transmit sensor information wirelessly to an external electronic device. The sensor system further includes a compression assembly for fixing the sensing element to the cage while maintaining the sensing element applied against an outer surface of the container in a highly conformable manner. The compression assembly includes components for attachment to the cage bars, and one or more springs bias the sensing element against the container.

A sensor system is described that can be attached to the outside wall of a nonmetallic container located within an outer cage, and that measures with high resolution a level of liquid inside the container using capacitance changes at the sensor system. The sensor system includes a sensing element having a metal channel that houses a foam ribbon, and a conductive strip is applied to the foam ribbon oppositely from the metal channel to form a capacitor. Sensor electronics can determine capacitance changes from which the liquid level is determined, and can transmit sensor information wirelessly to an external electronic device. The sensor system further includes a compression assembly for fixing the sensing element to the cage while maintaining the sensing element applied against an outer surface of the container in a highly conformable manner. The compression assembly includes components for attachment to the cage bars, and one or more springs bias the sensing element against the container.

A pressure vessel assembly incudes a pressure vessel and a gas density gauge. The pressure vessel includes a vessel wall defining an interior cavity. The gas density gauge includes a parallel plate capacitor having a pair of plates. Opposing surfaces of the plates are separated by a distance across an open gap. A capacitance of the capacitor is related to a density of a gas within the open gap.

A liquid leak detector for a pump is described. The liquid leak detector is mountable on a pump to detect leaked fluid coming from the pump. The leak detector includes a buffer tube positioned on the pump to collect a leaked fluid from the pump and a sensor positioned on the buffer tube to detect the level of leaked fluid in the buffer tube and to generate a signal when the leaked fluid reaches a maximum fluid level. A purge line on the buffer tube removes leaked drive fluid from the buffer tube once the leaked drive fluid reaches a maximum level. Logic connected to the sensor receives the signal from the detector and generates an alarm.

Provided is a liquid sensor or the like that is relatively easy to manufacture. The liquid sensor includes a light emitting element, an optical waveguide, a light receiving element, and a detection circuit. The optical waveguide includes a first pillar portion, a first metal plate, a second pillar portion, and a second metal plate. The first metal plate is embedded in the first pillar portion. The second pillar portion is provided at a position opposing the first pillar portion. The second metal plate is embedded in the second pillar portion. A space for liquid is formed between the first pillar portion and the second pillar portion. The first pillar portion includes a first end surface that faces the light emitting element. The first metal plate includes a first reflecting portion that is tilted relative to the first end surface and reflects light toward the second pillar portion. The second pillar portion includes a second end surface that faces the light receiving element. The second metal plate includes a second reflecting portion that is tilted relative to the second end surface and reflects the light from the first metal plate toward the light receiving element.

A smart hydration reservoir includes a flexible sensor which can be attached to the outer surface of any kind of the hydration reservoir and monitor changes of capacitive data of the hydration reservoir while user drinks the liquid which makes changes of the liquid level. The capacitive data is inputted into the controller; the controller will calculate the liquid level and then send out the information of the liquid level to the hand held device, such as specified display or mobile phone. Thus, the user can easily notice the liquid level of the hydration reservoir. The whole hydration detecting assembly can be easily installed to any hydration reservoir bought from the market.