Time for an update- It took until today for me to get the time to put it all together. With a couple of fittings from the House of Hose, I got the Valley Ind. gun attached to my electric (1200psi) pressure washer.
The gun works great- the front handle pivots to change from a stream to a very fine mist. Looks like it works very well for spraying trees. In the stream position I could just barely hit the peaks of my roof from the ground, which is at least 30' up.
I did notice that with the pressure washer turned off (but the house water still on) the sprayer could also reach the peak, but with less flow. So in full-stream mode putting the pressure washer in the middle does nothing but add to the GPH put out.
The problem came in the area that was the sketchiest- when I try to feed the pressure washer from a bucket (simulating a water/pesticide mixture) then the washer wants to stall. I'll still need to hook up some kind of booster pump between my spray tank and the pressure washer to get this all working.
So what does the Valley gun buy me that the washer won't do by itself? Just the ability to change the spray pattern- from dense fog to a stream. Well, that and the way-cool motorcycle gripped gun with the bright red end....
Since the control on the gun can be used to turn off the spray completely (stalling the pressure washer) it looks like it work would for most any GPM pump, not just something that throws 30gpm at 1000psi, as my washer is far less than that. I've not yet measured it, but I doubt I was doing more than 2gpm max.
Next up- rig it up with my 25g spray tank as the source. I might yet buy the PTO pump, as that solves the issue, but to save cash maybe I'll try a pump or two I have laying around here first. I really only need to use this twice a year, so don't want to sink too much in to it.
But I like the gun.