12) Equipment of bottom heater with short element type "FAST", size 125 x 63 mm; output 250 watts.
The standard version already includes the top and bottom heaters, both equipped with quartz heating elements of 250 mm standard length. The general arrangement is that the top heater features 2 short (i.e. halves) rows of heating elements which always ensures the necessary overlapping of the elements. The bottom heater has one row less, also because of the overlapping of the heating elements. Why just the bottom heater? Heat rises, hence the heating from below is always better mixed than that from above. This ensures more uniform heating from below so that one row less has no effect.
However the equipment with an element grid of approx. 250 x 100 mm is relatively coarse and for some applications a finer grid would be better. Options 12) to 15) have been developed for this purpose. Option 12) allows to divide in half the element size of the bottom heater, option 13) of the top heater. If this division in half is still not sufficient, it is possible to choose an element size of one third of the standard size, see options 14) and 15).
As mentioned above, it is mostly more sensible to choose the grid of the top heater elements smaller than that of the bottom heater elements. This is due to the higher proportion of heating by convection (hot air goes up) when heating from below so that mixing is improved.
There are however cases where a finer gradation of the bottom heater pattern is to be recommended. These could be coextruded materials with a highly sensitive bottom layer. Also, the handling is simplified if both heating patterns are identically equipped. Storekeeping of spares is also simplified. Please note that we ALWAYS use a single type of heating elements of one single size. This means that the customer has to store only one type of one size as spares.
The different variations from options 12) to 15) can be combined arbitrarily. No matter which combination you choose, the overlapping of the elements of top and bottom heater patterns is always ensured. The experience of 30 years guarantees always optimal uniform heating!
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