AR21038 | Mini-Matic 4/B Unloader Valve 2.1mm Fixed 2600 PSI

AR21038 | Mini-Matic 4/B Unloader Valve 2.1mm Fixed 2600 PSI

The Annovi Reverberi AR21038 Mini-Matic 4/B Unloader Valve is a compact,
purpose-built component engineered for systems that need stable, pre-set pressure regulation
without on-site adjustment. Using a fixed 2.1 mm orifice, this valve delivers
consistent performance at up to 2,600 PSI and 4.0 GPM, making it
an excellent choice for professional and light-industrial pressure washer applications where
repeatability, simplicity, and pump protection are priorities.

By diverting water into bypass mode whenever the spray trigger is released, the AR21038 prevents
pump overload, pressure spikes, and premature wear. Because it is factory calibrated rather than
field adjustable, it eliminates user error and is ideal for fixed-flow systems where consistent,
repeatable operating conditions are more important than on-the-fly tuning.

Key Features

• Pressure rating: Up to 2,600 PSI (Mini-Matic class).
• Flow range: Supports up to 4.0 GPM.
• Valve type: Mini-Matic 4/B unloader with fixed 2.1 mm orifice.
• Function: Automatic bypass pressure regulation and pump protection.
• Connections: ½” FNPT inlet and 3/8″ MNPT outlet.
• Construction: Heavy-duty brass body with corrosion-resistant internal components.
• Bypass operation: Automatically diverts water into bypass during idle cycles.
• Pump compatibility: Designed to work with XT, XM, and RC series pumps.

System Fit & Compatibility

• Part of AR’s Mini-Matic 4/B line, engineered for professional-grade compact systems.
• Integrates seamlessly with XT and XM pump series commonly used in commercial rigs.
• Optimized for RC series pumps for correct fit and flow without modification.
• Factory-set 2.1 mm orifice delivers consistent performance across the supported flow range.
• Ideal where operators want pre-set, factory-calibrated performance rather than field adjustment.

Installation Guidelines

1. Completely depressurize the system before installing the AR21038.
2. Mount in-line using the ½” FNPT inlet and 3/8″ MNPT outlet; verify all fittings are leak-free.
3. Route the bypass line directly back to the pump inlet or a supply tank—never restrict or cap the bypass.
4. No pressure adjustment is required; the fixed orifice maintains regulation automatically.
5. Test the system under normal operating load to confirm stable pressure and smooth bypass operation.

Benefits of Fixed-Orifice Design

• Consistency: Eliminates user adjustment errors and provides repeatable system behavior.
• Durability: Fewer moving parts reduce wear and extend service life.
• Efficiency: Maintains balanced output across repeated cleaning cycles.
• Simplicity: Fast to install and easy to standardize across multiple machines.

Typical Applications

• Fleet maintenance: Truck and bus wash systems requiring stable, consistent pressure.
• Contractor rigs: Portable cleaning units that see repeated daily use.
• Equipment wash stations: Industrial and agricultural machinery cleaning.
• Commercial facilities: Warehouses, garages, and building maintenance systems.
• Light industrial operations: Medium-duty applications needing fixed, repeatable output.

Repair & Maintenance

• Flush the system after use to help prevent debris buildup inside the valve.
• Inspect seals and O-rings regularly; rebuild kits are available from AR North America.
• Monitor bypass line temperature during long idle cycles to avoid overheating.
• Minimal maintenance is required thanks to the simple fixed-orifice design and reduced adjustment points.

Shipping & Support

• Ships via UPS Ground, typically within 24 hours (allow 2–3 business days during peak season).
• Supported by AR North America with technical resources, compatibility charts, and service parts.

Specifications

• Model: AR21038 Mini-Matic 4/B (fixed 2.1 mm orifice)
• Maximum pressure: 2,600 PSI
• Maximum flow: 4.0 GPM
• Inlet: ½” FNPT
• Outlet: 3/8″ MNPT
• Bypass: Integrated automatic bypass
• Materials: Brass body with corrosion-resistant internal parts
• Pump compatibility: XT, XM, and RC series pumps

AR21038 | Mini-Matic 4/B Unloader Valve 2.1mm Fixed 2600 PSI:

The AR21038 Mini-Matic 4/B Unloader Valve is a fixed-flow,
factory-calibrated solution for contractors, facility operators, and light industrial users who
need reliability, simplicity, and consistent performance. With its 2.1 mm fixed orifice, robust
brass construction, and automatic bypass operation, it offers a low-maintenance, professional-grade
safeguard for pumps and pressure wa