Technical parameters of heating elements
The technical parameters of electrical heating elements mentioned in this chapter are to be considered as basic data only. They are intended for customer's orientation when discussing an order with the Sales Department of Backer Elektro CZ.
These parameters are essential when the customer's requirements cannot be satisfied with our offer of several hundreds types of heating elements from our assortment. In such a case, a consultation with the Technical Department of Backer Elektro CZ is necessary. Thus, a heating element with required characteristics for the given application can be designed and manufactured.
SHAPES AND TYPES OF HEATING ELEMENTS
An electrical heating element consists usually of one or more tubular heating rods, connecting means for electrical connection, and heads or flanges for mechanical fixing.
The heating rods can be of circular or flat-oval cross section. The sheath of the heating rod consists of a metal tube of specific dimensions that is made of a suitable material, according to the given application. The surface of this metal sheath can be further treated so that to increase its resistance against surrounding environment. To improve the heat transfer of air and gas heating elements, these can be provided with ribbing made from a steel tape wound perpendicularly around the heating rod. Some heating elements intended for special purposes can be casted into a casting of required shape. For this purpose, mostly aluminium is used.
The resistive heating wire with output pins or output stranded wires is inserted inside the metal tube into an insulating material. The tube is then sealed and closed so that its inside active parts are thoroughly protected from all influences from the environment.
The heating rods, as the basic semi-product, can be processed in variety of shapes, meeting the requirements of the customer, depending on the final equipment where they are applied (up to the maximum operating pressure of 6.4 MPa).
An electrical heating element can be optionally equipped with various types of heads or flanges for mechanical fixing at assembly. The heating element can also be equipped with suitable connecting means for connection to the electrical circuit.
All electrical heating elements manufactured by Backer Elektro CZ are designed and produced in accordance with standard EN 60335-1.
At Backer Elektro CZ, we are proud to have mastered the technology of thick film heating elements. This advanced technology process provides perspective opportunity to use heating elements of this kind in common as well as in completely new areas of application. The heating material is applied in a form of a paste on a suitable ceramics or stainless steel substrate (plate) of specific quality. The heating part is isolated from the substrate and from the surrounding environment by thin layers of special insulating material that is applied in a form of a film.
Circular profiles
- Cross section of a circular rod
- Bending conditions of circular profiles
Flat-oval profiles
- Cross section of a flat-oval rod
- Bending conditions of flat-oval profile
- Schematic arrangement of resistive wire spirals in rods of flat-oval cross section
| SHEATH MATERIAL, CHARACTERISTIC FEATURES, FIELD OF APPLICATION | ||||
|---|---|---|---|---|
| Material | Acc. to ČSN Acc. to DIN Acc. to ASTM |
Max. surface temperature (°C) |
Characteristic features |
Field of application |
| Steel | 11343 St 34-2 - |
400 | heating of air up to 400 °C, heating of oil, alkaline bathes, contact heating | |
| Stainless Steel | 17240 1.4301 304 |
750 | heating of air, gases, contact heating | |
| Stainless Steel | 17246 1.4541 321 |
750 | good corrosion resistance |
heating of liquids, gases, contact heating, infra heaters, grills |
| Stainless Steel | 17349 1.4404 316L |
750 | very good corrosion resistance | generatig of steam, wet - dry cycling, heating of highly chlorinated water |
| Stainless Steel | - 1.4876 (Incloy 800) - |
900 | high corrosion resistance, heat resistance | storage heaters, aggressive liquids |
| Stainless Steel | 17251 1.4828 302B |
900 | heat resistance | storage heaters |
| Copper, nickel plated copper | - Cu-DHP - |
200 | water heating, water heaters, dishwashers, washing machines | |
| Flat-oval profiles can be used up to maximum surface temperature of 550 °C and they are, among others, also suitable for contact heating. | ||||
| SPECIFICATION OF HEATING RODS | |||
|---|---|---|---|
| Profiles (mm) | Production lengths (mm) | Sheath material | Bend inner radius R |
| ø 6.4 | 250 - 2300 | steel ČSN 11343 stainless steel DIN 1.4301, 1.4404. 1.4541, 1.4828, 1.4876 | minimum R 10 |
| ø 8.5 | 250 - 8300 | steel ČSN 11343 stainless steel DIN 1.4301, 1.4404. 1.4541, 1.4828, 1.4876 copper Cu-DHP |
minimum R 10 (depends on wall thickness) |
| 6.2 x 11.5 | 150 - 4500 | steel ČSN 11343 stainless steel DIN 1.4541 copper Cu-DHP |
minimum R 10, flat bending R 20 |
| 5.5 x 13,0 | 150 - 4500 | steel ČSN 11343 stainless steel DIN 1.4541 copper Cu-DHP |
minimum R 10, flat bending R 20 |
| 6.0 x 15 | 150 - 4500 | steel ČSN 11343 stainless steel ČSN 17248 copper Cu-DHP |
minimum R 10, flat bending R 20 |
| ø 10.0 * | 60 - 160 | stainless steel DIN 1.4541 | cannot be bent |
| ø 12.5 * | 60 - 160 | stainless steel DIN 1.4541 | cannot be bent |
| ø 12.0 ** | 400 - 1100 | stainless steel DIN 1.4541 | cannot be bent |
| * Only heating cartridges for heating of plastics moulds, heating of machines and their accessories ** Only for heating of water in radiators and bathroom dryers. |
|||
| SPECIFIC LOAD OF SHEATH SURFACE | ||||||||
|---|---|---|---|---|---|---|---|---|
| Application | Maximum temperature of heated medium (°C) |
Maximum surface specific load (W/cm2) | ||||||
| steel 11343 St 34-2 |
steel 17240 1.4301 AISI 304 |
steel 17349 1.4404 AISI 316L |
steel 17246 1.4541 AISI 321 |
steel 17251 1.4828 AISI 302B |
steel Incol. 800 1.4876 |
copper Cu-DHP |
||
| Steady water | 100 | - | - | 10 | 10 | - | - | 10 |
| Spinning water (washing machines) | 100 | - | - | 14 | 14 | - | - | 14 |
| Running water (instantaneous water heater) | 60 | - | - | 25 | 30 | - | - | 25 |
| Pressure water | 200 | - | - | 10 | 10 | - | - | 10 |
| Alkaline baths | 100 | 6 | - | 8 | 8 | - | - | - |
| Highly chlorinated water | 100 | - | - | 10 | - | - | 10 | - |
| Acid baths | 100 | - | - | 2 | - | - | 2,5 | - |
| Phosphating baths | 100 | - | - | 4 | 4 | - | - | - |
| Light oil | 250 | 2 | - | - | 2 | - | - | - |
| Heavy oil | 100 | 1,5 | - | - | 1,5 | - | - | - |
| Frying oil | 250 | - | - | 5 | 5 | - | - | - |
| Oil radiators | 80 | 6 | - | - | 6 | - | - | - |
| Asphalt, tar | 100 | 1 | - | - | 1 | - | - | - |
| Glycerine | 150 | 2 | - | - | 2 | - | - | - |
| Lead | 500 | - | - | - | 4 | - | - | - |
| Air | 50 200 - 450 |
1,5 - |
5 4 |
- - |
5 4 |
6 5 |
6 5 |
- - |
| Flowing air 5 m/s | 50 200 |
3 1,5 |
8 5 |
- - |
8 5 |
9 7 |
10 7,5 |
- - |
| Flowing air 10 m/s | 50 200 450 |
5 2 - |
10 8 4 |
- - - |
10 8 4 |
10 9 6 |
10 9 6 |
- - - |
| Storage stove | 600 | - | 4 | - | 4 | 4 | 4 | - |
| Contact heating | 300 | 2 | 4 | - | 4 | 6 | 6 | - |
| For casting into castings | 300 | 18 | 18 | - | 18 | - | - | - |
| Maximum specific load of flat-oval profiles is limited to 3 W/cm2, with an exception of casted elements (e.g. in aluminium), the specific load of which can be higher. | ||||||||