Datasheet

Kanthal Appliance Alloys Handbook 23
6
6. Element types and heating applications
The Embedded
Element Type
The wire in the embedded element type is
completely surrounded by solid or granular
insulating material.
Figure 3. Permissible D/d ratios as a function of
wire temperature in supported spiral elements.
Metal Sheathed Tubular
Elements
KANTHAL D is generally the best heating
wire for tube temperatures below 700 °C
1290
° F and NIKROTHAL 80 for tempera-
tures above.
To use KANTHAL instead of NiCr gives the
following advantages:
– Lower wire weight by some 20-30 % at
the same wire dimension
– More even temperature along the element
and lower maximum wire temperature.
This means that the element can be
charged higher for a short time - impor-
tant when there is a risk of dry boiling
– Closer tolerances of rating. Rating and
temperature remains more constant since
the resistivity in hot state does not change
as much as for NiCr
– Longer life at high surface loads. The ele-
ment life is also easier forecasted
– KANTHAL is easier to manufacture
when high resistance per length is needed,
since a thicker wire can be used
– Less sensitive to corrosion attacks
The Supported
Element Type
The wire, normally in spiral form, is situated
on the surface, in a groove or a hole of the
electrical insulating material.
KANTHAL AE, KANTHAL AF and
NIKROTHAL 80 are generally the best
materials.
In order to avoid deformations on horizontal
coils, the wire temperature should not ex-
ceed the values given in Figure 3.
The Suspended
Element Type
The wire is suspended freely between insu-
lated points and is exposed to the mechani-
cal stress caused by its own weight, its own
spring force and in some cases also from the
forces of an external spring.
NIKROTHAL 80, NIKROTHAL 60,
KANTHAL D and KANTHAL AF are the
best materials.
1200
105
°C
1100
1000
900
800
15 20
D/d ratio
2190
° F
2010
1830
1650
1470
KANTHAL AE
KANTHAL D