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Open Coil Element AKINSUN open coil elements are precision wound from high quality Nickel-Chromium and other popular heating alloys. Over the years we have produced helical coiled heating elements to meet specific design requirements. Knowing the operating temperature is important. Wire selection is based on operating temperature. Calculation of resistance or the wattage is based on the following ohm law. Using letters to represent quantity: R = Resistance (ohms)
W = Watts
E = Volts (Electromotive Force)
I = Current (Amperes)
E = I x R, or I = E/R, R = E/I
The ratio between watts and any two of the above factors is as follows:
W = (ExE)/R = E�/R, W = IxE. Coil to wire diameter ratioThe ratio of a coil is the relationship of its outside diameter to the diameter of the wire. Recommended coil ratio is between 5�:1 and 12:1. Very high and a very low ratio tends to make a coil difficult to manufacture. Stretch ratio Stretch ratio of a coil is its stretched length divided by its close wound length. Stretching a coil provides a space between each turn of wire to keep the coils from short circuiting each other and burning out. In order to obtain even heat distribution the spacing between should be uniform. For good heat distribution stretch ratio should be 2:1 to 4:1. | 
