Mastercool 90411 — Flex Adapter with Ball Valve 1/4" to 5/16" SAE (1/2-20 UNF) for R410A

Essential R410A Adapter: Convert Standard Hoses for High-Pressure Systems

The Mastercool 90411 flex adapter with ball valve is the essential tool for servicing R410A air conditioning systems with your existing 1/4" SAE charging hoses. This adapter converts standard 1/4" SAE connections to the 5/16" SAE (1/2-20 UNF) connections required for R410A's higher operating pressures, whilst the integrated ball valve provides precise flow control and safety.

Why R410A Requires 5/16" Connections

R410A refrigerant operates at significantly higher pressures than R22 and other older refrigerants — up to 70% higher on the high side. To handle these increased pressures safely, R410A systems use larger 5/16" service ports instead of the standard 1/4" ports. This larger connection provides:

• Higher Pressure Rating — Safely handles R410A's elevated operating pressures
• Increased Flow Capacity — Larger bore allows faster refrigerant transfer
• Reduced Restriction — Less pressure drop during charging and recovery
• Industry Standard — All R410A equipment uses 5/16" service ports

Integrated Ball Valve for Control and Safety

The integrated ball valve provides instant, positive shut-off with a simple quarter-turn. This gives you precise control over refrigerant flow and adds an essential safety feature:

• Flow Control — Start and stop refrigerant flow instantly
• Safety Shut-Off — Close valve before disconnecting to contain refrigerant
• Quarter-Turn Operation — Simple, reliable on/off control
• Leak Prevention — Positive shut-off prevents refrigerant loss
• One-Hand Operation — Easy to use whilst managing hoses

Flexible Design with Swivel Connection

The flexible adapter design with swivel connection makes installation and positioning easy, even in tight spaces. The swivel allows the hose to rotate freely, reducing stress on connections and making it easier to work around obstacles in cramped engine bays or equipment compartments.

Key Features

• Converts 1/4" SAE to 5/16" SAE — Use standard hoses with R410A equipment
• Integrated Ball Valve — Quarter-turn flow control and safety shut-off
• 1/2-20 UNF Thread — Standard R410A service port connection
• Swivel Connection — Reduces stress, easy positioning
• Flexible Design — Works in tight spaces
• Brass Construction — Durable, corrosion-resistant
• High-Pressure Rated — Designed for R410A operating pressures

Technical Specifications

• Model: 90411
• Input Connection: 1/4" Male Flare (SAE)
• Output Connection: 5/16" SAE (1/2-20 UNF swivel)
• Valve Type: Ball valve, quarter-turn
• Design: Flexible adapter with swivel
• Material: Brass
• Application: R410A refrigerant systems
• Pressure Rating: Suitable for R410A operating pressures

Perfect For

• HVAC technicians servicing R410A air conditioning systems
• Converting existing 1/4" hose sets for R410A use
• Mobile service operations working with multiple refrigerant types
• Residential and commercial R410A installations
• Heat pump service and maintenance
• Any application requiring 1/4" to 5/16" SAE conversion

Why You Need This Adapter

• R410A Compatibility — Essential for servicing modern A/C systems
• Use Existing Equipment — No need to buy complete new hose sets
• Ball Valve Safety — Integrated shut-off prevents refrigerant loss
• Professional Solution — Industry-standard adapter design
• Cost-Effective — Convert existing hoses instead of replacing them
• Versatility — Work on both R410A and traditional systems

Understanding R410A Service Requirements

R410A is a high-pressure refrigerant blend that has largely replaced R22 in residential and light commercial air conditioning. Key differences include:

• Higher Operating Pressures — Up to 70% higher than R22
• 5/16" Service Ports — Larger connections for safety and flow
• POE Oil — Requires polyolester lubricant (not mineral oil)
• No Mixing — Cannot be mixed with R22 or other refrigerants
• Dedicated Equipment — Requires R410A-rated tools and hoses

How to Use

1. Connect to Hose — Screw adapter onto your 1/4" SAE charging hose
2. Close Ball Valve — Ensure valve is closed before connecting to system
3. Connect to R410A Port — Thread swivel connection onto 5/16" service port (1/2-20 UNF)
4. Open Valve — Quarter-turn to open and allow refrigerant flow
5. Service System — Charge, recover, or evacuate as needed
6. Close Valve — Quarter-turn to close before disconnecting
7. Disconnect Safely — Remove adapter with refrigerant contained

Part of the Mastercool Flex Adapter Range

The 90411 is part of Mastercool's comprehensive flex adapter range:

• 90355: 1/4" MFL x 3/16" FFL (High-Side) GM 1976+, Ford 1981+
• 90356: 1/4" MFL x 1/4" FFL
• 90410: 1/4" MFL x 1/2-20 UNF-FFL (converts to 5/16" SAE, no valve)
• 90411: Flex Adapter with Ball Valve (this model - with flow control)

The Smart Solution for R410A Service

The 90411 flex adapter with ball valve is the professional solution for R410A service. Instead of investing in complete new hose sets, simply add this adapter to your existing 1/4" hoses and you're ready for R410A work. The integrated ball valve adds safety and control, whilst the flexible swivel design makes installation easy even in tight spaces. This is the adapter that belongs in every HVAC technician's toolbox.

Convert standard hoses for R410A. Integrated ball valve for safety. Professional flex adapter design.