K3.0 Pressure Washer Unloader Valve 2.1–3.0 GPM 400–1450 PSI – OEM Replacement Part
Part Number: 1593
Category: Pressure Washer Parts → Unloader Valves → Flow Actuated Unloader Valves
Type: General Pump K3.0 Pressure Washer Unloader Valve
The General Pump K3.0 Pressure Washer Unloader Valve (Part #1593) is a genuine OEM replacement flow-actuated unloader valve designed for commercial, residential, and light industrial pressure washer systems operating between 2.1 and 3.0 GPM with adjustable pressures from 400 to 1,450 PSI. Manufactured by General Pump, the K3.0 features a balanced piston design that delivers smooth pressure regulation, reliable bypass operation, and superior protection for pumps and high-pressure components.
Key Features & Benefits
- Genuine General Pump OEM replacement unloader valve
- Flow-actuated balanced piston design
- Designed for 2.1–3.0 GPM pressure washer systems
- Adjustable pressure range from 400–1,450 PSI
- Maximum operating pressure of 1,450 PSI
- Balanced nozzle technology minimizes pressure spikes
- Stainless steel and brass internal components
- Dual gauge ports for pressure monitoring
- Smooth transition between spraying and bypass operation
- Helps extend pump and hose life
- Commercial-grade durability
- OEM-quality fit and performance
Technical Specifications
Part Number: 1593
Manufacturer: General Pump
Model: K3.0
Product Type: Flow Actuated Unloader Valve
Flow Range: 2.1–3.0 GPM
Maximum Flow Capacity: 3.0 GPM
Pressure Adjustment Range: 400–1,450 PSI
Maximum Pressure: 1,450 PSI
Maximum Temperature: 195°F
Inlet Connection: 3/8" BSP-F
Outlet Connection: 3/8" BSP-M
Bypass Connection: 3/4" BSP-M
Gauge Ports: Dual
Operation Type: Flow Actuated
OEM Replacement: Yes
How the K3.0 Works
The K3.0 regulates pressure using a balanced piston and flow-actuated design.
When the spray gun is open:
- Water flows normally through the unloader.
- The balanced piston remains in the operating position.
- Full operating pressure is delivered to the spray nozzle.
When the spray gun is closed:
- Water flow stops.
- Pressure rises downstream of the internal orifice.
- The balanced piston shifts automatically.
- Water is diverted through the bypass circuit.
- Pressure spikes are minimized, protecting the pump and pressure washer components.
This balanced design provides smoother operation than conventional unloaders while reducing stress throughout the pressure washer system.
Common Applications
Residential & Commercial Pressure Washers
Ideal for:
- Residential pressure washers
- Portable pressure washer systems
- Vehicle washing
- Property maintenance
- Light commercial cleaning
Industrial Cleaning Equipment
Suitable for:
- Equipment wash stations
- Agricultural cleaning
- Maintenance departments
- Small industrial cleaning systems
- Custom pressure washer builds
Performance Benefits
- Precise pressure regulation
- Smooth bypass operation
- Reduced pressure spikes
- Improved pump protection
- Consistent cleaning performance
- Extended equipment lifespan
- Lower maintenance costs
- Reliable OEM durability
Signs an Unloader Valve Needs Replacement
Inspect or replace the unloader if you notice:
- Pressure fluctuations
- Reduced cleaning pressure
- Water leakage around the valve
- Difficulty adjusting pressure
- Inconsistent bypass operation
- Delayed trigger response
- Excessive internal wear
Installation Notes
- Verify compatibility with your system's flow and pressure requirements.
- Install using the appropriate BSP fittings and thread sealant.
- Connect the inlet, outlet, and bypass ports according to the pressure washer plumbing layout.
- Install a pressure gauge using one of the dual gauge ports for accurate adjustment.
- Set the operating pressure using a calibrated pressure gauge.
- Maintain a minimum 5% bypass flow for proper operation.
Important: Ensure all pressure washer components—including pumps, hoses, spray guns, fittings, and nozzles—are rated for the intended operating pressure before placing the system into service.
Maintenance Recommendations
- Inspect the unloader regularly for leaks and wear.
- Verify pressure settings during routine maintenance.
- Keep inlet water filtration clean.
- Maintain the recommended minimum bypass flow.
- Replace worn seals and internal components using genuine OEM repair kits.
- Follow General Pump recommended maintenance intervals.
