Des câbles chauffants autorégulants empêchent la solidification d’une solution corrosive stockée dans des réservoirs en plastique

Le défi
Il est souvent demandé au fabricant des équipements d’origine d’installer du matériel de chauffage sur les réservoirs destinés aux installations extérieures. Les clients finaux demandent des réservoirs en fibre de verre chauffés pour empêcher la solidification des produits chimiques stockés qui est causée par le gel et/ou pour limiter la viscosité liée à la température dans le but de faciliter le pompage. Ils ont besoin d’un moyen abordable pour chauffer de manière uniforme et en continu un réservoir à 60 °F, par exemple.

Le problème est que le réservoir en fibre de verre s’abîme en cas de température supérieure à 190 °F. Cela se produit surtout à l’endroit où le réchauffeur est monté sur la paroi du réservoir.

The Solution
One of the sales engineers at the nearby Chromalox sales office recommended the use of self-regulating heating cable as ideal for this application. The fact that it can be wrapped around the tank for even heating and is available in a variety of wattage ratings makes heating cable 'an excellent selection. In addition, with Chromalox self-regulating heating cable, there is a definite limit as to how high the cable surface temperature can rise even under worst case conditions', This limit is dependent on how the cable is applied.

For one particular application, the sales engineer recommended 100 ft. of 10 watt/ft. 240 volt self-regulating cable as adequate to maintain losses with 2" of foam insulation around the tank. The cable was applied to the tank wall with Chromalox AT-1 aluminum tape. He explained that even on loss of control the self-regulating heating cable inherently limits its own temperature.This application was therefore, inherently fail sale, since there was no way for the cable surface temperature to exceed the 190° F necessary to damage the fiberglass. Also recommended was a Chromalox 3912 series digital indicating 1/4 DIN temperature controller for on/off control. The controller was mounted remotely in a central control location.

The 3912 series temperature controller was used but is not longer produced. The modern replacement would be a HTLS single loop control panel.

Benefits

  • Fail safe: With Chromalox's exclusive self-regulating feature, the cable cannot exceed the temperature required to damage
    fiberglass tanks (when installed as described).
  • Even heating: The cable can be mounted to provide any heating pattern desired for uniform heating around the tanks.
  • Inexpensive: Total installed cost of the heating system was less than 10% of the selling price of the tank.
  • Attractive: The customer stated that the appearance of the 3912 controller alone would enhance the sale of future heated tank systems.
  • Single source: It is almost always more convenient and often less expensive (taking paperwork and customer's time into account) to purchase a complete system from a single source.