Hi Robert.
The Backpack system I use is not a converted sprayer, though I did experiment with some ideas like that for a while.
The problem with a sprayer is that, although it is possible to get the pressure needed, you would need to pump it continually to maintain a good enough flow rate. This is a problem because WFP needs two hands most of the time.
For this reason I abandoned the idea and built an electrically powered backpack system from scratch with the help of another forum member called Jeff.
Building the backpack was not as simple as you might imagine. It took many months to get right, and there are still aspects of it that could do with imrovement. I was told at the time that it would be an ongoing project, and that is exactly right.
Backpacks are great for the odd difficult task, especially where the site has restricted access. But their problem is that the capacity is limited, only 10 Litres. (Your sprayer holds 25 litres, the problem with having a tank that size is that when its electrically powered, there is also the weight of the pump and battery. The battery especially is quite heavy)
I doubt that I'd be able to manage with 25 litres on my back all day. Even after just a few hours use you feel the strain on your neck and shoulders.
If I'm honest, I like to have the pack in the van because it comes in handy, but I don't use it that much these days. I have a trolley system now, and also whenever I can I pump the water directly from the van, as this is much easer.
Using a WFP can be hard work, especially if over 30ft. Doing that also with a heavy backpack on takes weeks of practice. Personally I would wait until you have a proper system, and have got used to using wfp before thinking about a backpack, rather than starting off with one.
-Philip
