AN Fitting Adapters: ORB to Barb and NPT to Hose Barb

By DeatschWerks | Published: 2026-10-30

Category: Buying Guides

Learn how to choose between ORB-to-barb and NPT-to-hose-barb adapters for your fuel system, with clear decision rules and trade-offs.

Quick answer

Choose an ORB-to-barb adapter when your component has an O-ring boss port and you need a leak-resistant seal; choose an NPT-to-hose-barb adapter when you're connecting to a tapered pipe thread port.

ORB vs NPT: What's the difference?

ORB (O-Ring Boss) fittings seal with an O-ring compressed against a flat face, which makes them more tolerant of vibration and repeated assembly. NPT (National Pipe Taper) threads rely on the thread taper to create a seal, so they need thread sealant and can be more prone to leaks if over-tightened.

Your choice depends on the port you're connecting to. If your fuel pump, regulator, or rail has an ORB port, an adapter with an ORB male end is the direct route. If you're working with a component that uses NPT threads, you'll need an NPT adapter.

Hose barb sizing matters

The hose barb size must match the inside diameter of your hose. A 5/16-inch barb fits common 5/16-inch fuel hose, but always verify your hose's inner diameter before ordering. Using a barb that's too large or too small can cause leaks or make the hose hard to clamp.

Also consider the barb style: multiple barbs grip the hose better than a single barb, especially under pressure or in high-vibration areas.

Decision rules for choosing an adapter

Identify the port type: Check whether the component has an ORB port (flat face with O-ring) or an NPT port (tapered threads). This determines which adapter end you need.
Match the hose size: Measure the inside diameter of your hose and choose a barb that matches. For 5/16-inch hose, look for a 5/16-inch barb. Always double-check your hose ID before ordering.
Consider the seal method: ORB adapters with an O-ring are easier to seal and can be reused without thread sealant. NPT adapters require thread sealant and careful torque to avoid leaks. If you're frequently disconnecting and reconnecting, ORB is often more convenient.
Check the finish and material: Anodized finishes, like matte black or DW Titanium, resist corrosion and wear. Choose a finish that matches your system's aesthetics and environment. Anodized fittings are generally more durable in harsh conditions.
Verify the AN size compatibility: If you're adapting from an AN size to a barb, make sure the AN size matches your existing lines or fittings. For example, an 8AN ORB adapter is for 8AN systems. Mismatched AN sizes will not seal properly.

Product facts

1/8 in NPT to 5/16 ines Hose Barb Adapter: The DeatschWerks 1/8 in NPT to 5/16 in Hose Barb Adapter features a 1/8 inch NPT male thread and a 5/16 inch hose barb with an anodized matte black finish. This adapter lets you connect a 5/16-inch hose to a small NPT port, which is common on some fuel filters and regulators.
1/8 in NPT to 5/16 ines Hose Barb Adapter
8AN ORB to 5/16 in Barb: The DeatschWerks 8AN ORB to 5/16 in Barb fitting has an 8AN ORB male end, a 5/16 inch male triple barb, and includes an O-ring. The triple barb provides a secure grip on 5/16-inch hose, and the included O-ring helps create a leak-resistant seal at the ORB port.
8AN ORB to 5/16 in Barb

Fit guidance

Best for

Fuel systems with ORB ports on pumps, regulators, or rails that need a reliable O-ring seal
Custom plumbing where you need to connect 5/16-inch hose to AN or NPT ports

Not for

Applications requiring a permanent, vibration-proof seal without thread sealant (choose ORB with O-ring instead of NPT)
Hoses larger than 5/16-inch ID unless you find a matching adapter