| | | | | | | | | | | | | | | | | | | | | | | | | |
| | | |
| | | | | |
| | | |
| | | 2.To use the formula below, insert the no heat factors, diameter and width (in inches). Heated Area = (3.14 x Diameter - No-Heat Factor) x Width | | |
| | | MI Band Applications and Technical Data Calculating Watt Density Watt density is the amount of wattage per square inch of heated area. To determine watt density, divide the total wattage by the heated area. | | |
| | | Heated area is the total contact surface of the heater less areas of no heat that are found around terminals, mounting holes, etc. Heated Area = Total Contact Area - No-Heat Area To calculate the heated area: 1. Locate the no-heat factor from the chart below that corresponds to the type of heater being considered. | | |
| | | |
| | | |
| | | Total Watts Heated Area | | |
| | | |
| | | Watt Density = | | |
| | | | | | | | | | Type | Factor | | | | | (in.) | | | | 1 pc. lead unit Type B, C, | | | | | H, E or 90°B | (1.37) | | | | 1 pc. post terminal | (1.60) | | | | 2 pc. expandable post term | (3.18) | | | | 2 pc. expandable lead unit | (3.00) | | | | | | | | | |
| | | |
| | | |
| | | To apply this equation we must define the term "heated area." | | |
| | | |
| | | |
| | | Maximum Allowable Watt Density The following derating factors apply to the Maximum Allowable Watt Density chart, which are shown in both metric and inch base for convenience. Please review these factors and the chart to determine the correct watt density curve for your application. | | |
| | | Derating Factors: • For units over 51 mm (2 in.) in width, multiply wattdensity by 0.8. • In applications where unusual operating conditions are present, such as irregular mounting surfaces, contact the Watlow factory in St. Louis, Missouri, for watt density limitations. | | |
| | | • For two-piece units used in vertical applications, refer to Clamping Matrix Application Guide, page 21. • For applications where insulating blankets are used, multiply W/cm2 (W/in2) by 0.75. | | |
| | | |
| | | |
| | | |
| | | 20 | | |
| | | |
| | | | | | | | | | | | | | | | | | | | | | | | | |