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Air quick-coupler plug profiles: industrial M / H / G, Tru-Flate T, ARO A, European 7.2, Japanese, Lincoln, Schrader (tip diameter and length)
Which air coupler plug is which: how big are the tips of industrial (Milton M-style), Tru-Flate (T-style), ARO (A-style) and European plugs, and do they interchange? · Standard part · basis: Park Tool's published tip diameter (A) and tip length (B) table for each plug profile, with naming and standards from Wikipedia, Milton distributor listings, Guardair and Prevost; numbers only
Also called: air coupler sizes, milton m style plug dimensions, t style vs m style air coupler, a style air coupler aro 210, tru flate coupler dimensions, industrial vs automotive air coupler, air plug tip diameter, iso 6150 b plug, european 7.2 air coupler, 1/4 industrial air coupler dimensions, milton h style 3/8 plug, air coupler profile chart, aro 210 plug size, air chuck plug profiles, g style air coupler
Exact dimensions. True size, with no tolerance added.
- sizes
- 17 in table
Notes
- Plug profiles are distinguished by the tip (the nose that enters the coupler): tip diameter A and tip length B, as Park Tool names them. Two plugs with the same tip diameter are NOT interchangeable if the tip length differs: 1/4 in industrial (M) is 5/16 in × 3/16 in (7.94 × 4.76 mm); 1/4 in ARO (A) is also 5/16 in diameter but 5/16 in (NPT) or 3/8 in (BSPT) long; 1/4 in Tru-Flate (T) is 3/8 in × 1/16 in; 1/4 in European is 3/8 in × 3/16 in. The 'flow size' is the plug and coupler body size (1/4, 3/8 ...), not the thread on the back of the plug.
- Naming. Park Tool uses the Milton letters: M-style (1/4), H-style (3/8), G-style (1/2) for the industrial profile; A-style for ARO; V-style for European. Guardair calls the industrial profile 'Industrial Interchange, also M-style, I/M-style, Type-D' and the European one 'High Flow: V-style, Megaflow, European interchange'. A Milton A-style plug is sold as interchanging with ARO 210 and a Milton T-style plug as interchanging with the Tru-Flate / Parker series (Hi-Line listings). Park Tool and the Hi-Line listing label the Tru-Flate series differently (Park Tool 'automotive'; Hi-Line 'Tru-Flate / Parker industrial interchange series'), so the T-style name is what to match, not the word automotive or industrial.
- Standards (Wikipedia, Air-line fitting): the US industrial 1/4 in (M) profile is listed under A-A-59439, ANSI T3.20.14-1990, MIL-C-4109F and ISO 6150 B, and ISO 6150 B is cited for the US industrial 1/4, 3/8 and 1/2 in profiles; ARO 210 is DN 5.5 and ARO 310 DN 9; the European 7.2 is DN 7.2/7.4 and Eurostandard 10 DN 10; no standard is listed there for the T or A profiles. Prevost's ISO 6150 B safety couplings (ISI 06) have a 6 mm passage and G1/4, G3/8, G1/2 male thread bodies (A 76.3 / 78.3 / 82.3 mm, B 30 mm, C 20 / 23 / 26 mm on the datasheet; the letters are not defined in the text read). The ISO 6150 B plug drawing and the size designations such as B-12 are not in a document we could read, so no ISO plug dimensions are listed.
- Single source for the numbers: Park Tool's table is the only document read that prints tip diameter and length (inch, with the mm it prints); no second maker table was found, so treat the figures as a guide to telling profiles apart, and measure a plug with calipers before ordering the other half. The mm values here are the inch value × 25.4 rounded to 2 decimals; Park Tool's own mm figures are within 0.03 mm of them.
- Not published as numbers in anything read: the groove, shoulder and sleeve geometry, the thread on the back (typically 1/4 or 3/8 NPT, but varies by part) and plug body diameter. No file is drawn. McMaster-Carr sells quick-disconnect plugs and sockets, including ARO style, with per-part STEP; its air-coupling pages are linked, not copied.
- Related: camlock (cam and groove) couplings for liquids and bulk hose: camlock-couplings. Push-to-connect tube fittings for pneumatics: push-to-connect-fitting-sizes.
Air quick-coupler plug profiles: industrial M / H / G, Tru-Flate T… size chart
| profile (Milton letter) | flow size | tip diameter A | tip length B |
|---|---|---|---|
| Industrial | 1/8 in | 1/4 in (6.35 mm) | 1/8 in (3.17 mm) |
| Industrial (Milton M-style) | 1/4 in | 5/16 in (7.94 mm) | 3/16 in (4.76 mm) |
| Industrial (Milton H-style) | 3/8 in | 7/16 in (11.11 mm) | 5/16 in (7.94 mm) |
| Industrial (Milton G-style) | 1/2 in | 9/16 in (14.29 mm) | 3/8 in (9.52 mm) |
| Industrial | 3/4 in | 13/16 in (20.64 mm) | 5/16 in (7.94 mm) |
| Tru-Flate (Milton T-style, automotive) | 1/4 in | 3/8 in (9.52 mm) | 1/16 in (1.59 mm) |
| Tru-Flate (automotive) | 3/8 in | 7/16 in (11.11 mm) | 1/8 in (3.17 mm) |
| Tru-Flate (automotive) | 1/2 in | 9/16 in (14.29 mm) | 1/8 in (3.17 mm) |
| ARO (Milton A-style), NPT | 1/4 in | 5/16 in (7.94 mm) | 5/16 in (7.94 mm) |
| ARO (Milton A-style), BSPT | 1/4 in | 5/16 in (7.94 mm) | 3/8 in (9.52 mm) |
| ARO (Milton A-style), NPT | 3/8 in | 7/16 in (11.11 mm) | 9/16 in (14.29 mm) |
| European (Milton V-style, Megaflow, NT 7.2 / DIN 7.2) | 1/4 in | 3/8 in (9.52 mm) | 3/16 in (4.76 mm) |
| Japanese | 1/4 in | 7/16 in (11.11 mm) | 7/32 in (5.56 mm) |
| Silverline bayonet (UK) | 3/16 in | 5/16 in (7.94 mm) | 11/32 in (8.73 mm) |
| Lincoln | 1/4 in | 9/32 in (7.14 mm) | 3/4 in (19.05 mm) |
| Schrader quick-connect (twist lock) | 1/4 in | 5/16 in (7.94 mm) | 3/4 in (19.05 mm) |
| Schrader quick-connect (twist lock) | 1/2 in | 1/2 in (12.7 mm) | 7/8 in (22.22 mm) |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
Xem scan
File coming
No downloadable true-size file yet: the published figures do not fix the whole shape, and Xem never guesses a number. A measured scan is planned; request it and it moves up.
https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.Plain text: sheet.txt · JSON: /api/geometry?object=air-quick-coupler-plug-profiles
Fits with
Questions
What is the difference between M-style and T-style air couplers?
Same 1/4 in flow size but different tips: M (industrial) is 5/16 in diameter and 3/16 in long; T (Tru-Flate) is 3/8 in diameter and 1/16 in long (Park Tool). They do not interchange.
Do M-style and A-style plugs interchange?
No. Both have a 5/16 in tip diameter, but the A (ARO) tip is longer: 5/16 in (NPT) or 3/8 in (BSPT) against 3/16 in for the industrial M tip.
What is a 3/8 in H-style plug?
Milton's name for the 3/8 in industrial (Industrial Interchange) profile: 7/16 in tip diameter, 5/16 in tip length (Park Tool).
Which profile is ISO 6150 B?
Wikipedia lists ISO 6150 B against the US industrial 1/4, 3/8 and 1/2 in profiles (the M, H and G profiles); the standard's own drawing was not readable.