Air actuated versus electric nozzles
What are the differences between these two systems that control the on/off cycles of spray nozzles?
Actuation response time
The electronic nozzles, (either the EHPI industrial model or the EHP advanced model), have much faster response times than the air actuation (PHP) nozzles.
These have response times of between 50 cycles per second on the EHPI, or up to 150 cycles per second on the EHP system.
In contrast, the air actuated nozzle (PHP) can be cycled off, under normal circumstances, three times per second when using spring actuation overcome by air. Air resistance is air shutting them both on and off, and this can be increased up to ten times per second.
That’s still fast and impressive for most spray systems, but nowhere near as fast as the EHP and the EHPI nozzle which are nearly an order of magnitude or over an order of magnitude faster with those electronic nozzles. That poses many different possibilities with those types of electric nozzle.
Cost
The air actuated nozzles (PHP), have a distinct advantage in that they’re an awful lot cheaper than the solenoid control valves.
However, they still need to have a solenoid valve added to the cost of the nozzle to give that control. But a single solenoid valve on air actuated nozzles could be used to control multiple nozzles, so the cost of those solenoids can be spread out over all the nozzles on a spray bar. One actuating air supply can be controlled by a single solenoid, and this lowers the cost considerably.
The EHP nozzles in contrast, have their own integrated solenoid in each of the nozzle bodies.
Essentially, with one rapid response valve for each of the nozzles, the cost of those nozzle bodies will increase.
Overall, there’s a distinct cost advantage of the air actuated nozzles. But they are more expensive to run compared to the electronically controlled ones; compressed air is used to run them, rather than a small electrical signal that turns them on and off directly.
Pressure range
What pressure ranges can these two types of nozzle cope with?
The electronic nozzles (advanced EHP models) can cope with up to 17 bar of fluid pressure. It has a very rapidly responding solenoid valve in there, and that means it can’t be very tightly wound. It can't hold back pressures much above 17 bar.
The industrial EPHI model, which is still electronically actuated, is slightly tighter wound on the solenoid which gives it a less rapid response time. But that means it can handle up to 20 bar of fluid pressure. Overall, it has slightly higher pressure than the more advanced EHP model.
When compared to the pneumatically air actuated nozzle (PHP), which can handle up to 40/41 bar, it’s clear that there’s a much bigger pressure range in there. And that gives some advantages when spraying certain types of fluids.
If highly viscous fluids are being sprayed for example, higher pressures are likely required to spray them, and that might be out of the range of the electronically controlled nozzles.
In which case, an air actuated nozzle is needed to form the spray system.
Compressed air
The electronic nozzles don’t need a compressed air supply and the pneumatically controlled nozzles obviously do. This can be a critical deciding factor in which to go for.
If there’s a good air supply present, that opens the possibility of having a pneumatically controlled nozzle. If the air isn't there, then there’s no choice.