NPT Tapered Male x UNO O-Ring Boss Male Straight Adaptor

NPT tapered one end, SAE O-ring boss the other. Converts an American pipe-thread line into a UNO port on a pump, motor or valve without changing anything else in the run.

Brand: Ayrtec – mild steel body with a plated finish, manufactured to the standards listed below.

Watch: 90 ° Hydraulic Adaptors How They Work and the Importance of O'Rings

Thread Standards

• NPT Tapered Male – ANSI/ASME B1.20.1 tapered pipe thread. It seals on thread interference, so tape or sealant is a must.
• SAE O-Ring Boss Male (UNO/UNF) – SAE J1926 / ISO 11926 straight thread O-ring boss. It seals on an O-ring squeezed against the port spotface, not on the thread.

How to Choose

• One end seals on the thread and one seals on an O-ring. Sealant on the NPT end only.
• A UNO male will start into a BSPP port and strip. Both are straight threads with different pitches, so check the callout.
• The UNO port spotface has to be clean and unmarked. A scored face weeps past a good O-ring.

Technicians Advice

Do not use the NPT end as a handle to wind the UNO end home. Get the UNO in first with the ring oiled, seat it properly, then work on the pipe thread. Loading a tapered thread while the O-ring is still finding its seat is how both ends end up wrong.

Where You’ll Find It

• NPT Tapered Male – American-built gearboxes, pumps, compressors and older industrial pipework.
• SAE O-Ring Boss Male (UNO/UNF) – Cylinder end caps, pump and valve bosses on US-built plant. Common on Australian-assembled cylinders too, where it is usually called UNO.

Cross-Reference

• NPT Tapered Male – ANSI/ASME B1.20.1 tapered pipe thread. The dryseal variant is written NPTF.
• SAE O-Ring Boss Male (UNO/UNF) – SAE J1926 / ISO 11926 straight thread O-ring boss. Also written ORB, SAE ORB or UNO. Thread form is UN/UNF.

Parker, Gates, Aeroquip and Ryco all manufacture to these same standards under their own part numbering, so a fitting built to the standard above will mate with theirs.

Cross-references are given at series level as a guide to the standard, not as a part-for-part substitution. Always confirm the thread form, size and seal type against the port before ordering.

📐Dimensions & thread sizes – every size in this range

← Swipe the table sideways to see every measurement →

Part code	A	B	L	H1	Material	Finish
NTM-UNM-0609	9/16" UNO	3/8" NPT	34mm	20.6mm	Mild steel	Plated finish
NTM-UNM-0612	3/4" UNO	3/8" NPT	37mm	27.0mm	Mild steel	Plated finish
NTM-UNM-0614	7/8" UNO	3/8" NPT	39mm	28.6mm	Mild steel	Plated finish
NTM-UNM-0812	3/4" UNO	1/2" NPT	40mm	22.2mm	Mild steel	Plated finish
NTM-UNM-0814	7/8" UNO	1/2" NPT	43mm	25.4mm	Mild steel	Plated finish
NTM-UNM-0817	1.1/16" UNO	1/2" NPT	47mm	31.8mm	Mild steel	Plated finish
NTM-UNM-1212	3/4" UNO	3/4" NPT	45mm	28.6mm	Mild steel	Plated finish
NTM-UNM-1214	7/8" UNO	3/4" NPT	43mm	28.6mm	Mild steel	Plated finish
NTM-UNM-1217	1.1/16" UNO	3/4" NPT	47mm	31.8mm	Mild steel	Plated finish
NTM-UNM-1621	1.1/16" UNO	1" NPT	47mm	1.5/16mm	Mild steel	Plated finish

Key: L overall length, H1 centre to face 2. Measurements in millimetres unless shown otherwise. Thread columns show what each end mates with. Dimensions are nominal – check critical clearances against the part.

Downloads

📄 Thread Identification Chart (PDF)

Same Threads, Other Angles

🔗 90° Compact – same threads

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Need a hand? Call 1300 146 737 or email sales@mhfgc.com.au – real technicians, real answers.