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Thermocouples-mantle
Thermocouples-
mantle- also known as mineral-isolated thermocouples- are widespread in the
temperature measuring technique. Because of their advantages of the mechanical
and measurement techniques, they have been superseded the conventional thermocouples.
Furthermore, they also have put on the new ways for the problems, of which the
solution is difficult or negative, on measuring tasks at thermometry; for example:
at the construction of nuclear centrals, on the comprehensive chemical technics
and at the other places.
Thermo wires of the thermocouples with a mantle are embedded in compressed oxide
powder and coated by the metal mantle with thermic resistance. This structure
method supplies the following advantages:
1. Thermocouples- Mantle can be produced in expected length
2. These elements can be bent in each place and thus, they can be extended to
the measurement places where is difficult to be reached. The bends or distortions
do not cause refraction and short circuit on wires. The long pieces are coiled
to the bobbins.
3. They have high vibration resistances since they do not contain any components
which can be come into vibration ( isolating pipes …etc )
4. Its thermo wires and measuring points are protected against to the oxygen
and harmful gases by its hermetical outer mantle. Thereby a good resistance
is also ensured with small diameters.
Technical Data:
Insulation Resistance : > 1000 M Ohm (at room temperature )
Minimum bend diameter : 2x mantle diameter
Each thermocouple is subject to the following tests :
Insulation resistance ( Thermopair against to the mantle ) :
> 100 M Ohm (at room temperature ) is measured by 250 V direct voltage
Cable diameter > is measured at 1.5 mm by 100 Volt direct voltage
Mantel transmission diameter < 1; % mm
Density (test point) Test pressure is 40 bar , at room temperature with nitrogen.
Thermovoltage
:
Batch test up to 1000°C depending upon material
Routine Test at 300 °C
Tolerance according to DIN 43710 and/or DIN International Electronical
Commission 584-1, K1.2
Mantle-Thermocouples- Remarks
Standart
Mantle thermocouples:
Mantlethermocouples Ni Cr Ni
|
Article
Nr. . |
Diameter
Mantle |
Length
|
Dedector length |
|
780
002 0100 |
1,0
mm |
300
mm |
100
mm |
|
780
002 0500 |
1,0
mm |
300
mm |
500
mm |
|
780
002 1000 |
1,0
mm |
300
mm |
1000
mm |
|
780
002 1500 |
1,0
mm |
300
mm |
1500
mm |
|
780
002 2000 |
1,0
mm |
300
mm |
2000
mm |
|
780
002 2500 |
1,0
mm |
300
mm |
2500
mm |
|
780
002 3000 |
1,0
mm |
300
mm |
3000
mm |
|
780
002 3500 |
1,0
mm |
300
mm |
3500
mm |
|
780
002 4000 |
1,0
mm |
300
mm |
4000
mm |
There can be a few lengths which do not meet to the standarts !
Protective pipe from quartz glass for mantle thermocouples
| Article Nr. : | Description: |
| 780 003 30 |
External diameter ca. 3,0 mm inner diameter ca. 1,6 mm Straight part ca. 100 mm, Angel part ca. 135° and 25 mm long |
Sockets and clamps:
Ceramic groove feedthrough bushes, series and equipment clamps, provide for
a safe cable entry by sheet metal enclosure /walls/constructions. It has temperature
resistant and as abrasion safety device opposite the electrical cords of IR
- transmitter or also different cables.
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Mantle –
Thermocouple – Materials
| Normal
Implementation : Measuring points against to the isolated Mantle The thermopair is welded and isolated against to the mantle. The mantle is solder with the gas-tight locked by a spacer in the same type of material. The gap is filled out with magnesium oxide powder. . Grounded Implementation : Thermopair with welded mantle The Thermopair is welded into the lamella surfaces, There is a galvanic connection between the thermocables and the metal mantle. This kind of welding is implemented only on express desire. Mechanical forces, harmful for the element, arise by the rigid connection between thermocables and mantle due to the different thermal expansion. Morever, inevitable thermal material arrives into the welded joint of the ground panel, and thus, it leads to the change of its corrosion characteristics. If a best heat is transferred from the mass medium to the antenna, It reflects to the reaction periods for recovery . |
