1/2″ – 20  ,  5/8″ – 20  Fuel Inlet Fitting. SAE J512 Inverted Flare.

The 1/2″-20 and 5/8″-20 fuel inlet fittings refer to specific sizes of threads used in fuel line connections, particularly in automotive and machinery applications. These fittings play a crucial role in creating a secure and leak-proof connection for the flow of fuel, which is why their specification and compatibility with SAE standards are important.

Thread Size and Description:

• 1/2″-20 and 5/8″-20 refer to the size and pitch of the threads on the fitting.
  • 1/2″-20: This means the fitting has a nominal thread diameter of 1/2 inch, and a thread pitch of 20 threads per inch.
  • 5/8″-20: This means the fitting has a nominal thread diameter of 5/8 inch, and a thread pitch of 20 threads per inch.

SAE J512 Standard:

• The SAE J512 standard is a specification set by the Society of Automotive Engineers (SAE) for fittings used primarily in automotive and industrial systems, particularly for fuel lines, hydraulic lines, and refrigeration. It is a common standard for the design and performance of fittings that ensure a reliable and secure seal.
• The SAE J512 Inverted Flare fitting type is typically used in fuel, brake, and hydraulic systems.
• Inverted flare fittings use a conical seat and matching male and female parts to create a seal. The male fitting has an external inverted flare, and the female part has an internal mating flare that provides a metal-to-metal seal, reducing the risk of leaks, even under high pressure.

Application and Use:

1. Fuel Systems: These fittings are commonly used in fuel systems to connect hard fuel lines or connect flexible hoses to hard lines or components. They provide a tight and reliable seal that is ideal for handling gasoline or diesel fuel.
2. Brake Systems: Similar fittings are also used in brake systems, though the materials and specific applications may vary.
3. Hydraulic Systems: These fittings can be used to connect hydraulic lines in various machinery, as long as the application involves relatively lower pressure compared to dedicated high-pressure fittings.

Materials:

• Typically, these fittings are made from steel or brass. Brass is more corrosion-resistant and often used in fuel and refrigeration systems, while steel offers more durability and strength.
• For fuel line connections, it is important that the fitting material is compatible with fuel types (e.g., gasoline, diesel) and should resist corrosion over time.

Design and Functionality:

• Inverted Flare: The inverted flare connection uses a mating cone design to create a robust seal.
  • The male fitting has a 45-degree inverted flare that matches with the female fitting.
  • This style of fitting is preferred for its reliability and its ability to withstand vibration and movement without loosening or leaking.
• Installation:
  • Proper torque must be used when installing these fittings to prevent overtightening, which can damage the threads or distort the flare, leading to leaks.
  • Conversely, under-tightening can result in a weak seal.

Common Applications:

• These fittings are used in a variety of vehicles and equipment, including automobiles, trucks, tractors, and small engines.
• In automotive carburetors or fuel injection systems, the correct size of the fuel inlet fitting ensures the proper connection between the fuel line and the carburetor/fuel rail.
• The use of SAE J512 inverted flare fittings in fuel systems helps ensure leak-free operation, which is critical in preventing fuel vapor buildup or leaks that could create safety hazards.

Compatibility:

• These fittings are designed to be compatible with steel or copper tubing. Inverted flare fittings are not typically used with flexible rubber hose without the appropriate adapter.
• Ensuring that the fittings match the correct tubing size and material is essential for a proper fit and long-term reliability.

Summary:

• 1/2″-20 and 5/8″-20 fuel inlet fittings are commonly used in fuel, brake, and hydraulic systems.
• They follow the SAE J512 standard for inverted flare fittings, providing a reliable metal-to-metal seal suitable for handling fuel.
• These fittings can be made of steel or brass and are often found in applications where a secure, leak-proof connection is critical.

These types of fittings are often sourced through automotive parts suppliers, hardware stores specializing in fuel line components, or industrial supply shops. Proper handling, correct torque application, and ensuring material compatibility are all important to maintain safety and reliability when using these fittings.