Since the early days of the introduction of Pulse Width Modulation, BfS have been marketing PulZar nozzles throughout north America and Canada, and now the PWM nozzle systems are being offered on machines coming onto the UK market.
How they work
PWM systems control each nozzle separately, and the flow rate from each nozzle is managed by rapidly switching the nozzle control solenoid on/off. The duration that the nozzle is “on” is called the Duty Cycle and varying this duty cycle provides the operator with the ability to control the volume output from each nozzle.
- The system pressure, spray quality and fan pattern remain consistent.
- The system can cope with a five-fold change in forward speed without affecting output.
PWM bodies will enable the correct application from each nozzle even when going around a corner where the outer edge of the boom is travelling much faster than the inner edge, so giving a lower rate of application. PWM corrects this by changing the duty cycle at each nozzle to compensate accordingly.
Flat fan nozzles have been the main jet used but these are prone to create small, driftable droplets. The PulZar is a low drift jet perfectly suited to PWM systems, with most jets giving over 75% lower drift than conventional flat fans and some giving up to 91% lower drift.
Table 1. Calculated drift reduction and star rating for each nozzle/pressure tested
(CRD Ref. 190001-6, February 27, 2019)
|
Nozzle – Size
|
Pressure (Bar)
|
Drift reduction at
5 m, %
|
LERAP Star rating
|
| BfS PulZar 015 |
2.0
|
80.18
|
3
|
| BfS PulZar – 015 |
2.5
|
66.13
|
2
|
| BfS PulZar 025 |
2.0
|
81.15
|
3
|
| BfS PulZar 025 |
2.5
|
75.33
|
3
|
| BfS PulZar – 03 |
2.0
|
79.00
|
3
|
| BfS PulZar – 03 |
2.5
|
75.29
|
3
|
| BfS PulZar – 04 |
2.0
|
79.57
|
3
|
| BfS PulZar – 04 |
2.5
|
80.79
|
3
|
| BfS PulZar – 05 |
2.0
|
88.80
|
3
|
| BfS PulZar – 05 |
2.5
|
87.39
|
3
|
| BfS PulZar – 06 |
2.0
|
91.29
|
4
|
| BfS PulZar – 06 |
2.5
|
88.36
|
3
|
Note: Other spray nozzles may not work effectively on PWM systems, especially air inclusion nozzles.
BfS can provide the necessary advice if required.
