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A limit switch with a roller-lever operator; this is installed on a gate on a canal lock, and indicates the position of a gate to a control system A limit switch mounted on a moving part of a bridge In electrical engineering , a limit switch is a switch operated by the motion of a machine part or the presence of an object.
Overheating is prevented by a safety switch called a limit controller or limit switch. This limit controller may shut the furnace off if the blower fails or if something is blocking the air flow. The heated air is then sent back through the home through supply ducts. In larger commercial applications, central heating is provided through an air ...
In natural gas furnaces, water heaters, and room heating systems, a safety cut-off switch is normally included so that the gas supply to the pilot and heating system is shut off by an electrically operated valve if the pilot light goes out. This cut-off switch usually detects the pilot light in one of several ways: A flame rectification device. [2]
A thermal switch (sometimes thermal reset or thermal cutout (TCO)) is a device which normally opens at a high temperature (often with a faint "plink" sound) and re-closes when the temperature drops. The thermal switch may be a bimetallic strip , often encased in a tubular glass bulb to protect it from dust or short circuit .
Furnace: Cooling tower: Heat exchanger: Coil heat exchanger: Cooler: Plate & frame heat exchanger: Double pipe heat exchanger Fixed straight tubes heat exchanger: U-shaped tubes heat exchanger Spiral heat exchanger Covered gas vent Curved gas vent Air filter: Funnel or tundish: Steam trap: Viewing glass Pressure reducing valve: Valve: Gate ...
A Single-Pole, Single-Throw (SPST) mercury switch on millimetre graph paper, device length approximately 1.5 cm Another mercury switch design. A mercury switch is an electrical switch that opens and closes a circuit when a small amount of the liquid metal mercury connects metal electrodes to close the circuit. There are several different basic ...
Wire crossover symbols for circuit diagrams. The CAD symbol for insulated crossing wires is the same as the older, non-CAD symbol for non-insulated crossing wires. To avoid confusion, the wire "jump" (semi-circle) symbol for insulated wires in non-CAD schematics is recommended (as opposed to using the CAD-style symbol for no connection), so as to avoid confusion with the original, older style ...
Older furnaces sometimes relied on gravity instead of a blower to circulate air. [1]Gas-fired forced-air furnaces have a burner in the furnace fueled by natural gas.A blower forces cold air through a heat exchanger and then through duct-work that distributes the hot air through the building. [2]