This Pressure Regulator is designed for single or multiple pump, weep or multi-nozzle systems. This is a flow-thru design easily plumbed into the discharge line or directly onto the discharge head. This regulator maintains set system pressure even when only one of several guns or nozzles is performing or a solenoid valve is open, by-passing the unused flow. The pressure is held in the line during full by-pass and instantly has full pressure, when all guns and nozzle resume operation. 5-10% by-pass is necessary for optimum performance.