ZH288 Blue Spring Pressure Washer Unloader Valve – 1/2" NPT, 4500 PSI Upgrade your pressure washer system with the ZH288 Blue Spring Unloader Valve, engineered for high-performance, reliable pressure control. Designed for professional and industrial use, this valve reduces pressure loss, protects your pump, and ensures smooth operation. Easy to install and maintain, it’s ideal for hot or cold water systems up to 4500 PSI. Key Features: Trapped-pressure unloader design for fast, stable pressure regulation Reduced pressure loss for maximum system efficiency Extremely reliable for continuous-duty applications Easy maintenance and adjustment Protects pumps by diverting flow when the spray gun is closed How It Works: The ZH288 regulates system pressure by controlling bypass flow. Gun open: Valve maintains working pressure. Gun closed: Water is diverted through the bypass at low pressure, reducing pump stress. Zero-pressure mechanism: Keeps delivery and bypass lines connected during shutdown, lowering system pressure evenly. Installation Guidelines: Install upstream of any heat source in hot water systems Always use a safety relief valve Choose a nozzle that allows at least 5% bypass flow for stable operation Bypass water can be returned to the pump intake or to a tank with baffles to reduce turbulence and air bubbles Pressure Adjustment Tips: Adjust with system running and trigger gun open Turn adjustment knob to increase/decrease pressure If pressure does not rise, check nozzle size vs flow rate Replace worn nozzles to restore proper operating pressure 🚫 Do not remove the mechanical safety nut—it limits maximum pressure and protects the system Specifications Feature Details Maximum Flow 21 GPM Maximum Pressure 4500 PSI Maximum Temperature 195°F (continuous use recommended up to 140°F) Inlet Connections Dual 1/2" FPT Discharge Connection 1/2" FPT Bypass Connection 1/2" FPT Connection Type 1/2" NPT Media Clean, fresh water Application Hot or cold water pressure washer systems Pressure Adjustment Screw-type adjustment knob, adjustable while system running Ideal For: Commercial and industrial pressure washers High-flow pump systems up to 21 GPM Hot or cold water cleaning equipment Professional cleaning and maintenance operations
