[RonMar]

Most of the 25 gallon spot sprayers have a pump large enough to handle a small boom. Most of the pumps are rated in GPM at a given pressure. Most nozzels are also rated in GPM at a particular PSI so you know how fast to spray for a given coverage. If you can get pump and nozzel specs, you can put together the right combination. I think mine is 2.1 GPM at 40 PSI. I started out with a 80" coverage 2 nozzel boom and had no problem maintaining 40 PSI at the boom and was still dumping liquid back to the tank. I calculated that I could add another nozzel for 120" coverage, and still maintain 40 PSI with no excess being returned to the tank. This works great for me.

I was going to build my own originally, but after looking up all the parts, I found it pretty hard to beat the cost for a 25 gallon spot sprayer and a basic 2 nozzel boom kit($47?) from Agri-supply. The original manufacturer was Fimco, and I was able to order a matching additional nozzel and "T" from them directly when I upgraded to a three nozzel boom. I built a tow behind cart for it out of 1" box tube and two wheelbarrow wheels.