Air Adaptor for a US Tool? BSP vs NPT, ARO Plugs and PTFE Tape

A tool bought from the US or Europe arrives and its plug won’t go into your couplings, or a freshly fitted adaptor hisses however much tape it gets. The fix is usually to match the plug to your couplings and the thread to the tool, then seal it properly.

PartsForMachines stocks 193 airline adaptors and connectors from PCL, Sealey, SIP and Draper in its adaptors and connectors range.

Tool from the US or Europe? Which Plug Do I Fit to Match My Couplings?

Fit a plug of your own workshop’s profile to the tool, rather than changing your couplings to suit it. Swap the tool’s own plug for an adaptor that locks into your existing couplings.

Each plug profile matches a list of other makers’ coupling series. If the tool’s plug matches ARO 210, it is an A Style profile, like the ACA6923 A Style adaptor. Cejn 310 or Legris 24 points to ISO B12, and Nitto Kohki 200 or Rectus 13 to KF.

Running a second set of couplings for those tools? ISO B12, KF and PF adaptors, such as the AA7502, AA7802 and AA7702, all have male R 1/4 threads. If you can’t name the plug, photograph it beside a ruler and send it to us.

BSP or NPT: Why Won’t a US Tool’s Fitting Seal in My Line?

Because the threads don’t match: BSP threads have a 55° thread angle and NPT threads 60°, so the two cannot engage properly and are not interchangeable.

The fix is an adaptor whose thread matches the tool’s inlet. The screwed adaptors in this range have BSP threads, marked R or BSPT (taper male), Rp or G (parallel), such as the AC04 screwed adaptor, male 1/4in BSPT (pack of 5). For an NPT inlet, send our team the details from the tool’s manual before ordering.

PTFE Tape or Thread Paste: How Do I Stop a Screwed Adaptor Leaking?

Check the thread type first. On a taper male thread (R or BSPT) the seal is made in the thread, so it needs PTFE tape or a thread sealant, applied properly. A parallel G thread seals on a washer or O-ring, so more tape won’t cure it.

First make sure the hiss is at the thread, then clean off the old seal and wind on two or three turns of tape, following the way the thread spirals. Don’t let the tape overhang the end of the thread.

Kitting Out a New Compressor: Which Adaptors, and How Many?

Pick one coupling profile for the whole workshop, then allow one female coupling per hose end or outlet and one male adaptor for every tool, plus a few spares. Match each thread to the tool’s inlet and each hose tailpiece to the hose’s inside diameter.

The AC04 also comes in packs of 15 and 100, and the ACA2593 Standard plug also comes as a display pack of three. For a ready-made start, the Draper 64508 air connector kit has 15.2 m of 3/8in hose and a 600 mm whip. It adds a male taper plug, a female parallel coupling and a safety coupling.

What Should I Check Before I Order an Adaptor?

• your workshop’s coupling profile, and the interchange of the tool’s plug
• the tool’s inlet thread, especially on tools made abroad: BSP taper (R/BSPT), parallel (Rp/G) or NPT
• whether the port seals on the thread (tape or sealant) or on a washer or O-ring
• the part you need at that point: male plug, female adaptor, union or swivel
• how many you need, including spares: singles, threes, fives or bulk packs

Not sure? Contact the PartsForMachines team by WhatsApp, telephone or email with a photo of the old plug, or browse the adaptors and connectors range.

Product options, delivery options and returns terms are shown on each product page. A 30-day return policy applies to eligible items.

Frequently Asked Questions

Can over-tightening a screwed adaptor make it leak?

Yes, it can. Over-tightening can distort a taper thread and open a leak path, so extra force is not the cure for a hiss. If a firm joint still hisses, check that the thread types match before reaching for the spanner again.

Can I turn an air inlet through 90°?

Yes, with an elbow adaptor. The SIP 51384 is a 1/2in BSP male-to-female elbow that turns the line through 90°, for compressors, tools, hoses or pipework with a matching BSP thread.

What does a safety adaptor do?

It makes disconnecting under pressure safer. The AC88 screwed safety adaptor, for example, has a built-in choke that vents the air slowly when it is unplugged, helping to prevent hose whip. It has a male 1/4in BSPT thread.

Why fit a swivel adaptor?

It lets the hose turn at the connection, which reduces strain on the fitting and gives more freedom of movement. The ACX90 swivel adaptor has a male 1/4in BSPT thread.

How do I join two male threads?

Use a double female union. The SA1/1414FF has a 1/4in BSP female thread at each end, so two 1/4in BSP male threads can screw into it. Check that both male threads are the same size and form first.

What is a coned tailpiece with a union nut?

It is a hose-end fitting held by a separate threaded nut. The AC45 coned tailpiece suits 5/16in bore hose and takes a 1/4in BSP union nut. Spare AC48 union nuts, also 1/4in BSP, come in packs of five.

Can I connect to Schrader-type couplings or tyre equipment?

Yes, with a Schrader-compatible adaptor. Versions come with an R 1/4 or R 1/2 male thread or a 6.35 mm hose tailpiece, for example the ACAS104, ACAS203 and ACAS101.

Are there adaptors for nylon tube or ring-main pipe?

Yes. Mini tube adaptors such as the AA11RF8/6 take 8 mm o/d, 6 mm i/d tube, and ring-main adaptors such as the CAS15BSA convert 15 mm pipe to a 1/2in BSPT male thread.