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Clamping bands can be used to firmly fasten
strips longitudinally to large-diameter
cylindrical surfaces. |
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What is a Strip Heater?
The strip heater is an electrical heater which is mounted on a surface and used to heat the surface or air (gasses).
Application of OMEGALUX™ Strip Heaters
OMEGALUX™ strip heaters are used principally for convection-type air heating and clamp-on installations. When selecting strip heaters for either, two important factors must be considered:
- The proper sheath material for resisting any rusting and oxidizing inherent in the process or environment and for withstanding the sheath temperature required. Standard sheath materials are rust resisting iron, chrome steel and Incoloy (NS Series only). Stainless steel and Monel sheaths are available at an additional charge. Maximum work and sheath temperatures are below.
- The watt density of the element, or watts per square inch of heated area. This should be low for heating asphalt, molasses and other thick substances with low heat transferability; it can be higher for heating air, metals and other heat conducting materials. (See curves for determining allowable watt densities).
| Selection of Strip Heaters for Air Heating |
 |
1. Select maximum desired operating
air temperature on (D)
2. Choose either chrome steel sheath
or rust-resisting iron sheath (points E)
on basis of operating conditions
3. Draw straight line through points (D)
and (E) to reading on (F) giving maximum
allowable watts per square inch
4. Select desired length heater with
equivalent watt density or less |
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| Selection of Strip Heaters for Clamp-On Applications |
 |
1. Select maximum desired
work temperature on (A)
2. Choose either chrome steel sheath
or rust-resisting iron sheath (points B)
on basis of operating conditions
3. Draw straight line through points (A)
and (B) to reading on (C) giving maximum
allowable watts per square inch
4. Select desired length heater with
equivalent watt density or less |
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| Selection of Watt Density for Finned Strips |
 |
1. Select a maximum desired
air temperature on A
2. Choose sheath material
to suit operating conditions
3. Select minimum anticipated air
velocity on B.
Note: Natural circulation is equal to
one foot per second
4. Draw straight line through the points
selected on A and B–read C for
allowable watt density
5. Select required length heater
with equivalent watt density or less |
When high operating temperatures are needed, watt density must be limited in order not to exceed the maximum sheath temperature. Watt density is given in the "How To Order" table for each strip heater.
In general, a viscous material with low thermal conductivity requires a low watt density. High watt densities can be used with thinner liquids and with materials of high thermal conductivity. Premature loss of the element due to excessive temperature may result if the material's heat-take-away ability is low. Also, the material may be charred, carbonized or its chemical makeup altered by overheating. |
