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The most versatile of all electric heating elements,the tubular heater is
capable of being formed into virtually any configulation.
The range
of ratings,sizes,material and termination available makes the tubular adaptable
to many industrial,commercial and scientific applications.
The basic
design consists of a helical coil of resistance wire precisely centered in a
metal sheath.
This coil is surrounded by magnesium oxide power which
is vibration loaded to insure even density througth out the length of the
heater.
This entire assembly is then reduced ti the finished
diameter,compacting the Mgo freezing the coil in the center of the heater.
1. TUBULAR HEATER
CONSTRUCTION
(A)
Resistance Wire
Nickel-chromium wire is sized by computer
and precisely wound to provide the exact heat required. the wire is
washed and baked to eliminate contamination and give the user a
longer-lived heater. several tests during production guarantee final
resistance within specified tolerances.
(B) Insulation
The resistance wire assembly is centered
into the heater sheath and electrically insulated with magnesium
oxide power. the purity of this power is critical to heater life.
This insulation is compacted to a computer-determined desity when the
unit diameter is reduced by rolling. this increases its excellent
dielectric strength and greatly improves its thermal conductance.
bends are recompacted to eliminate potenstial insulation
breaks.
(C) Sheath Material
Copper,Steel,Stainless Steel,Incoloy are
available in seven standard diameters.
available in
6mm,8mm,11mm,12mm,14mm,16mm. all heaters are fully annealed unless
other wise specified.
SHEATH
ELEMENT & MAX. TEMPERATURE
|
Sheath material |
Max. Sheath
temp. |
Watt density |
Recommended
application |
|
COPPER |
174°C |
8.45 |
Water heating, water solutions
non-corrosive to copper. |
|
STEEL |
400°C |
3.41 |
Immersion in oils, molten salt baths,
alkaline cleaning solutions, tars and asphalt. Also suitable for clamping
to metal surfaces and casting into aluminum. |
|
STAINLESS |
650°C |
4.65 |
Corrosive liquids, food processing
equipment. |
|
INCOLOY |
760°C |
6.20 |
Air heating, radiant heating, cleaning
and degreasing solutions, plating and pickling solutions, corrosive
liquids. |
* Other sheath materials are also
available for application considerations.
Commonly specified are 316
stainless steel and 320 stainless steel for corrosive immersion
heating, copper clad steel for metal casting, Inconel for high temperature
applications, and titanium for severely corrosive solution heating.
Porcelain and ceramic coatings can also be provided for corrosive
atmospheres in process air applications, immersion heating, or for
other application considerations.
(D) terminal
The wire-to-pin connection is made by one
of several welding techniques,
selected for optimum life for the
heater size and rating. |
