PA VB280-VB350 Pressure Regulating Unloader Valves. Pressure regulating unloader valve. At gun shut off, the water flow is bypassed at reduced pressure. Assembly equipped with a high pressure proof compensation. Compact dimensions. Sturdy steel and brass construction. Adjustable locknut to control max pressure. Possibility to fit a venturi injector, on delivery, for chemicals. Nylon knob. By-pass G1/2 F. Easy maintenance.