SharpShooter
®
with Rate Sync
®
- Turf Sprayer Edition
©2003, 2011, 2015 Capstan Ag Systems, Inc., All Rights Reserved | Version:
P-3.0
| 6/9/2016
9.0 - Troubleshooting
60
For Advanced Rate Controllers with 3 PWM values:
1.
The 3 PWM values are: Maximum (253), Minimum (~60) and PreSet which is a value you may want to change
depending on a green/tee or fairway application. In general this is the value the PWM goes to when the booms
stops spraying. The smaller the difference between the operating PWM value and the Preset Value is, the more
optimum is the sprayer response and performance. However the Preset PWM value by the pump “boom off”
pressure that results from the PWM value.
To determine the Preset PWM value:
1.
Find the location in the rate controller where you can monitor the PWM value while spraying.
For an engine driven centrifugal pump with an inline flow control valve:
1.
Tune the valve calibration from 2123.
2.
Try varying the second digit from the right “2” (deceleration timing). The larger lengthens time and is more stable.
Try 2133, or 2143.
3.
Then increase the third digit from the right “1” (velocity of change) one number at a time. Increasing the number
makes the valve respond faster. For example: Change to 2143 to 2243, or 2343.
4.
Test each setting the balance of speed and stability. Typically when you increase the speed, you also need to
increase the deceleration time.
b.
PWM Close Valve: In this case when the boom is shut off, the pump stops. This creates a large issue for consistent
spraying and from spraying from a dead stop. It is done to prevent a diaphragm pump from continually building
pressure that could ultimately burst hoses, etc. This is overcome by continually using an agitation circuit as a pressure
relief circuit. Therefore the rate controller will have a Preset Agitation PWM setting to maintain a 60-70 pis agitation
pressure when the booms are off. Often users think the Preset Agitation is a pressure and set it too low. That PWM
value is typically around 100 to achieve a 60-70 agitation pressure.
a.
On fairways, using the maximum speed (typically 8-9 MPH) and your rate determine the operating PWM
value that will determine the Preset Value you want to use. With any Preset Value you use, check the
“boom-off” pressure. It should not exceed 100 PSI. If the pressure is too high, the Preset PWM will have to
be lowered.
b.
Do the same with the greens and tees. Given that the rates are higher and speeds are lower for greens, it
would not be unusual for the two PWM values to be close.
c.
If these two values are different, you consider editing the Preset Value for the two applications.
The object is to keep the minimize the recovery time of the pump to resupply the boom when changes to
speed, boom section or rate occurs.
In both cases above, it is then possible to adjust the rate controller valve calibration for a faster response,
but yet stable response.
