A

Ambient Temperature: The external surrounding temperature as distinquished from the temperature of the device it is desired to control.

B

Bimetal: A bonded laminate of two metals each having different temperature coefficients so arranged that the material deflects when subjected to a change in temperature.

Bimetal Etching: A process used to permanently mark one surface of bimetalic raw metal strip to distinquish the high expansion side from the low expansion side. It is normal to mark the low expansion side.

C

Calibration: The procedure used to adjust a thermostat into proper mechanical switching operation.

Calibration Temperatures: Those temperatures including tolerances which determine an acceptable product.

Close on Rise: A term used to indicate a device whose contacts must close with rising temperatures.

Contact Rating: An established max. operating limit of a device. Rating may be expressed as amperes, voltage or watts.

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D

Differential: The difference between the temperature to operate and the temperature to reset a thermostat.

Drift: The problem of a thermostat temperature setting shifting away from its initial set point.

E

Epoxy Seal: The sealing of a device against the entrance atmosphere contamination by the use of an epoxy film.

G

Gross Leak Check: A liquid test method devised to check for the presence of holes in a hermetically sealed device. Bubbles emanating from the device indicate gross leakage of atmosphere.

Grounded Case Device: A thermostat whose case and mounting are part of the electrical contact circuit.

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H

Hermetic Seal: A device which is sealed against entrance of atmospheric contaminants (moisture, dust, etc.).

High Expansion Side: That side of bimetal that will expand the greatest with variance in temperature.

L

Low Expansion Side: That side of bimetal that will expand the least with variance in temperature. It is usually identified with some type of marking.

O

Overshoot: The temperature of the medium or device which the thermostat is subjected to, which exceeds the maximum set or control point.

P

Probe: That portion of a thermostat which extends into the substance whose temperature the thermostat is sensing.

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T

Temperature Indicator: An instrument used to measure temperature such as a mercury thermometer or a thermocouple instrument.

Thermal Conductivity: The ability of a substance to transmit heat through its molecules.

Thermostat, Adjustable: A thermostat of any type whose set point or calibration may be adjusted within the designed temperature range.

Thermostat, Fixed Temperature: A thermostat of any type in which thge temperature setting or calibration is set at the factory.

Thermostat, Immersion: A probe type thermostatic device designed to sense temperatures of fluids.

Thermostat, Normally Closed: A thermostat with contacts that open on rising temperature. This type is generally a control or cycling thermostat; its contacts open at the set temperature shutting off the heat or cold source, closing again automatically at the low side of its differential.

Thermostat, Normally Open: A thermostat with contacts that close on rising temperature. A thermostat generally used as warning or top limit control, when overheat or cold must be known, its contacts close at the desired temperature. The contacts again automatically open at the low end of its design differential.

Thermostat, Surface Sensing: A thermostatic device designed to sense only the skin temperature of any material to which it is attached.

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