A fluid sensor (15) is disclosed. The sensor comprises a frame (21), first and second electrodes (271, 272) supported by the frame and separated by space occupiable by a fluid, and a third electrode (273) lying in a path (29) on the frame between the first and second electrodes.

A liquid level switch is provided having a first elongated substrate having one, two or three or more pairs of elongated electrical conductors thereon, a second elongated substrate having one two or three or more electrically conductive areas thereon, each electrically conductive area being positioned over an associated pair of electrical conductors positioned on the first elongated non-electrically conductive substrate for enabling electrical bridging contact between conductors of the pairs of electrical conductors, and a substrate coupler is provided for coupling the first and second non-electrically conductive substrates together for providing separation of the non-electrically conductive substrates in the absence of hydrostatic pressure thereon, and for causing contact between the first and second non-electrically conductive substrates in the presence of hydrostatic pressure thereon, producing the electrical bridging contact between pairs of conductors on the first non-electrically conductive substrate, in turn producing multiple level output signals.

A potassium nitrate level detection sensing module M in a strengthening furnace according to the present invention includes a level detection means, which is installed inside a glass strengthening furnace, installed at a height equal to a level line of strengthening liquid to be filled in the strengthening furnace F, and generates an electrical signal having a set threshold or more or an electrical signal having the set threshold or less when it comes into contact with the strengthening liquid and detects that the strengthening liquid filled in the glass strengthening furnace F has reached a set strengthening liquid level line. The potassium nitrate level detection sensing module in the strengthening furnace according to the present invention having such a configuration can automatically identify that potassium nitrate in a liquid state, which is melted in the strengthening furnace, has reached the set level line in the strengthening furnace.

A level gauge includes an input circuit, a sensor part, and switching means, the sensor part includes electrode pairs arranged in a liquid level detection direction, the electrode pairs are divided into n groups, the i-th (i=1, 2, . . . , n) group is constituted with an electrode pair at the 2.sup.i-1(2k1)-th (k is a natural number from 1 to 2.sup.n-i) position from the lowermost position, one ends of the electrode pairs are connected to the input circuit, and the other ends belonging to the same group are connected to each other in parallel and connected to the switching means.

A contacting device is provided for an impedance limit switch, the contacting device including: a printed circuit board having an electrically conductive contact surface; a radially disposed annular spring configured to establish electrical contact between the electrically conductive contact surface of the printed circuit board and at least one electrode of the impedance limit switch; and a non-conductive housing element. An impedance limit switch is also provided, including the contacting device; an electronic cup; and a measuring head configured to carry out a conductive and/or capacitive measurement and to record measurement data, the contacting device being configured to transmit the measurement data from the measuring head to the electronic cup via the contacting unit.

In a method for operating a household steam treatment appliance which includes an evaporator with a heatable water holding chamber and a fill level sensor with at least two measurement electrodes, which are disposed over one another at a distance from each other in the heatable water holding chamber, a water detection measured value provided for indicating wetting of the at least two measurement electrodes with water introduced into the water holding chamber is adapted in an adaptation process to an electrical conductivity of the water in the water holding chamber.

An electronic liquid level sensor configured to verify a height of a liquid in a reservoir between minimum and maximum levels includes at least one reference electrode, a minimum level electrode and a maximum level electrode. Each of the minimum level electrode and the maximum level electrode is configured as a pin having at least one tapered portion with a diameter between 0.010 and 0.035 at a widest point of the tapered portion, an angle of taper of the at least one tapered portion with respect to a longitudinal axis of the pin being between 181 and 193, a total length of the at least one tapered portion being between 0.110 and 0.150, and a radius of curvature of a tip of the pin being less than 0.015.