The PWM Health test is a useful tool for seasonal maintenance and for tuning an aftermarket or retrofit nozzle control system installation on a machine with a PWM pump.
The uses for this test include:
- checking if the existing pump is sufficient to control the system, (very important for an aftermarket or retrofit installation),
- tuning the pump duty cycle range to reduce lag or wind-up in control effort,
- and diagnosing flow restrictions like pinched plumbing, plugged strainers, and sticky cartridge valves.
The test will control the pump duty cycle from 0 percent, up to 100 percent, then back down to 0. Then it will measure the pressure response. It will identify any deadbands at the top and bottom of the pump operation. Then it will recommend minimum and maximum PWM values.
Before you run this test, make sure to set the maximum pressure so it does not exceed the safe pressure for the machine and nozzle control valves. 120 PSI is the recommended maximum pressure for the NCV2.
Refer to the calibration and operation manual for other safety information and how to run the test.
When the test is complete, you should see a smooth curve for the pump control for the increase and decrease in duty cycle. Any visible “steps” in the curve could indicate something like a sticky cartridge or other blockage in the pump. Inspect the pump and its components and clean and or replace things as necessary. If you see a narrow range in control, there could be a limitation with the pump, the chemical, or the engine RPMs may be too high during the test.
