Hello Guys,
We have been using modified stainless soda kegs for about five years. We install a stainless ball valve, a 6' hose and a trigger gun. This is the only way we apply any chems. It works great for house washing. Each wash rig has a 40 gallon tank (used propane tank) that we charge with a commercial compressor at the shop.
It's quick, and easy. No motors, no pumps, no batteries, no noise. We even use these to apply Ready Seal. On very large jobs that will deplete the 40 gallon tanks, we use CO2 to charge them.
See ya,
Rick