CISTERNS, CONTAINERS, BUNKERS & SCREENS
Elements of silicone rubber gives many advantages:
- Easy and quick installation.
- Resistant against the most frequent chemicals.
- Flexible at temperatures down to -28°C. Makes it easier to install during the cold season.
- Available in a large number of standard elements.
- Operating temperatures up to +250°C.
- The construction is easy to install in the most applications where the object is made of a heat conducting material, this admits also an excellent heat transfer from the element to the object.
At high power requirements or when the object has few free plain surfaces to cover with heat (a filter can be full of openings and a tank can be armoured), then elements of silicone rubber is a good alternative. They handle temperatures up to 250°C and have an output of 1W/cm²
To obtain a good heat transfer from the panel to the cistern (air is as is well known, a very good insulation), the panel is glued with silicone glue, type 732 RTV. A tube 732 RTV is enough to 2 panels 600 x 600 mm. This can be done in the following way:
- Remove the grease from the element and the surface where the element shall be installed with trikoretylen or equivalent.
- Distribute the glue evenly over the whole surface of the element, with a toothed glue spreader (minimum layer of glue approx. 0.5mm).
- Correct placement of the element is important in order to obtain the best functioning and best life time (if it is a cistern containing fluids in varying levels, shall the element be mounted so it will be under the fluid level. Is this not possible you can divide the application in two parts on the height with separate control.
- Mount the element against the cleaned surface and press out all air bubbles with a rubber roller or another round thing which is reeled on the outside of the element from the middle and outwards the edges. You can fix the elements with aluminium tape to keep them on place until the glue gets dry. Please note! The glue will dry in the edges first and at last in the middle.
Applications with silicone rubber element should normally be equipped with a quick control, for example a time proportional regulator with the transmitter placed against the heated surface or on the silicone element.
Heating of a round, standing tank of steel containing oil
|Diameter||=||Ø 1500 mm|
|Ambient- & start temperature:||=||20°C|
|Insulation D||=||0,05 m Mineral wool|
|Environment||=||The tank is placed indoors. Oil retarding can occur.|
|The density of the content G||=||0,9 (Kg/dm³)|
|Heat permittivity c||=||0,58 (Wh/ Kg°C)|
|Heating-up time h||=||24 hours|
|Volume V||=||p x r² x h =p x 7,5² x 30=5298 dm³|
|Ph =||V x G x c x th||=||5298 x 0,9 x 0,58 x 60|
Ph= 6913 W
|Ph||=||The required power to increase the temperature of a required temperature on h hours (W)|
|P||=||Total required power (W)|
|P||=||Q + Ph = 468 + 6913 = 7381 W|
The tank is made of steel and the oil withstands high temperatures so we choose silicone rubber element, which is glued against the outer side of the tank with silicone glue. Connection is done via temperature control.
We choose 6 elements 200 x 900 mm 1285W 230V which gives a total power of 7700W /230V.