The spreader constant is the amount of material discharged per revolution of the encoder on a belt or chain. This is defined in pulses per cubic foot or per cubic centimeter. Most encoders pulse 180 or 360 times per revolution, but there are other types available (a gear tooth sensor is one example). Please ensure the correct values are used for the encoder pulse. If the spreader constant number is too big (>99,999), then the sensor may need to be changed to a sensor with fewer pulses per revolution.
A spreader constant is needed to accurately measure the amount of dry product dispensing out of a machine. Raven controllers and field computers use this number in the calculation to speed up or slow down the bed that is being used. It is critical that this number is calculated properly. Many bed manufacturers provide a spreader constant table with their models of beds. This usually is the best source for finding the spreader constant number. In most cases, contact with the bed manufacturer will be the best way to find the spreader constant. In cases that the manufacturer is unavailable or the information is not available the following formulas may be used. Please use the best formula to suit your needs.
If calculating it manually, the following information will be needed:
* This number will be on the encoder. If the count is unknown, use the steps below:
The manufacturer spreader constant for 1.5 inch gate height is 1000, but you want your gate height to be 1 inch.
The US spreader constant is 909.
The Metric spreader constant is 3204.
This procedure is used to correct a spreader constant when doing a catch test. It can also be done in the field after applying a known amount of product.
The new spreader constant is 735.
If the 1 inch gate height is known, the spreader constants for other gate heights can be found using the following formula:
How to Convert Spreader Constant between US and Metric
US to Metric
Metric to US
Using a Known Spreader Constant on a Non-Granular Console
Enter the meter cal of 265 into the console.
Enter the meter cal of 584 into the console.
Catch Test Method Using a Spreader Constant on a Non-Granular Console
The new meter cal is 243.
Decimal Shift Method