The Pump Pressure Control Valve allows the operator to adjust the solution flow and pressure that discharges from the nozzles. The Pressure Gauge indicates the amount of pressure. Reducing the pressure decreases the volume of flow. The Valve will not slip, so pressure remains exactly as adjusted. When the Control Valve is fully closed, a by-pass allows the minimum solution flow necessary to prevent damage to the Pump system. A coupling welded into the piping, between the pump and the PBM, provides a large diameter, easy cleanout pressure tap point for a glycerin-filled Pressure Gauge. The Pressure Gauge assembly includes a Diaphragm Seal that prevents solution from entering the Gauge.