Technical Information
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- Technical Information
- The larger the disc, naturally the more energy is available.
- The disc’s reversal force is proportional to its area as well as to the temperature differential.
- The accuracy of an element is about 3°F.
- For temperatures below 250°F, use a differential >15°F.
- For temperatures above 250°F, the differential should be at least 25°F.
- Remember that all snap elements show some creepage, and this creepage is influenced by the temperature differential. The greater the differential, the less the creepage.
- Due to the variety of shapes, alloys and forming methods, no set formula has been established to give accurate design specifications. Therefore, we have set up the Demaich Samples Lab specifically to answer your questions.
Symbols Key
t = Thickness
w = Width in Inches
L = Active Length
D = Deflection
TP = Thermal Force – Ounces
MP = Mechanical Force – Ounces
F = Flexivity Valve (Flexivity Values)
Average the Flexivity values over your temperature design range
E = Modulus of Elasticity (Flexivity Values)T = Change in Temperature
Note: For maximum effectiveness and minimum volume of thermostat metal, use one half of the temperature change for deflection and the other half of the temperature change for the thermal force.
Cantilever
Disc
Simple Beam
U-Shape
Trip Temperature
The temperature at which snapover occurs when the element is heated.
Reset Temperature
The temperature at which the bimetal element reverses itself when cooled.
Delta
The difference in temperature between trip temperature and reset temperature. Generally delta is not less than 15°F.
Tolerance
The accuracy of the temperature response of the snap element. Usually it is ±2°F or more.
Movement
The total distance traveled by the work point of the element when snap-over occurs at the trip temperature.
Creep
The amount of movement by the work point of the element when heated from ambient temperature to the trip temperature, but not including snap-over.
Trip Side
For discs that have their trip above room temperature, the high expansion
side of bi metal, is the concave side of the element before reaching the trip temperature. The rule is opposite when the trip temperature is below
room temperature.
Reset Side
For discs that have their reset above room temperature, the low expansion side of bimetal, is the convex side of the element before reaching the reset
temperature. The rule is opposite when the reset temperature is below room temperature.
Load
Any physical force applied to either side of the snap element.
e.g. spring, fluid pressure, vibration, magnetism.