EKINSUN LTD is a custom parts manufacturer that machines push-in fitting bodies to drawing when the maker series does not fit: a male stud with an M14×1.5, M22×1.5 or 3/8 NPT thread on a 6 mm port, a 316L body for a washdown line, an elbow with a longer stud or a hex the series lacks, a bulkhead for a thick panel — with the collet, release ring and O-ring fitted from the series so the tube end behaves as it always did. Standard push-in fittings inside the grid are catalogue parts; what falls outside it is machined, from 1 piece.
A typical request: 14 mm tube into a G1/2 male, 800 pieces, the same in 10 mm to G3/8, and one odd one — 6 mm tube into an M12 x 1.5 sensor port.
The first two are series parts from the catalogue; the third is a machined body with a series collet.
Push-in fitting forms
| Form | Ports | Typical market code | Where it is used |
|---|---|---|---|
| Male straight | tube × male thread | PC | the stud fitting into a valve, cylinder or manifold port |
| Female straight | tube × female thread | PCF | tube onto a male port or nipple |
| Male elbow, swivel | tube × male thread, 90° | PL | turning the tube out of a port; body swivels before tightening |
| Female elbow | tube × female thread, 90° | PLF | tube onto a male port at a corner |
| Extended male elbow | tube × male thread, long | PLL | clearing a housing |
| Union straight | tube × tube | PU | joining two tubes inline |
| Reducing union | tube × smaller tube | PG | 10 to 8 mm, 12 to 10 mm and so on |
| Union tee | tube × tube × tube | PE | splitting a line |
| Male branch tee | male thread × tube × tube (branch threaded) | PB | a port with the line running through |
| Male run tee | tube × male thread × tube (run threaded) | PD | a port at the end of a run |
| Y fitting | tube × tube × tube in a Y | PY | gentle split, vacuum and beverage lines |
| Cross | four tubes | PZA | two lines crossing |
| Bulkhead union | tube × tube through a panel | PM | panel and tank walls — see bulkhead fittings |
| Bulkhead female | tube × female thread through a panel | PMF | panel with a threaded connection behind |
| Plug-in reducer | plug-in stem × smaller tube | PGJ | reducing at a fitting instead of inline |
| Speed controller | tube × male thread with a needle valve | SC / SL | meter-in or meter-out flow control on a cylinder port |
| Push-in check valve | tube × tube or tube × thread, one-way | — | see pneumatic check valves |
Codes such as PC, PL and PE are market aliases used by several makers and are not standards; the letters and suffixes vary by maker. Order by tube outside diameter and thread.
Need a push-in connection on a thread no catalogue lists? EKINSUN is a custom parts manufacturer: we make the threaded body or adapter for the push-in fitting to your drawing, sketch or sample — nickel-plated brass or 304 stainless steel — from 1 piece, quoted in 12 hours and shipped duties paid. Already a catalogue size? Ask us too — we may have it in stock, and larger quantities cost less per piece. All custom adapters and fittings →
Tube sizes: metric and inch are two series
| Tube OD | Series | Nearest in the other series | Note |
|---|---|---|---|
| 4 mm | metric | 5/32 in (3.97 mm) | close enough to confuse; a 4 mm fitting does not seal reliably on 5/32 tube |
| 6 mm | metric | 1/4 in (6.35 mm) | the commonest mix-up; 0.35 mm is more than the collet tolerates |
| 8 mm | metric | 5/16 in (7.94 mm) | — |
| 10 mm | metric | 3/8 in (9.525 mm) | — |
| 12 mm | metric | 1/2 in (12.7 mm) | — |
| 14 mm, 16 mm | metric | — | large pneumatic and beverage lines |
| 1/8 in (3.175 mm) | inch | 3 mm | — |
| 1/4, 5/16, 3/8, 1/2 in | inch | 6, 8, 10, 12 mm | US equipment; order the inch fitting, not the metric one |
Push-in fittings grip the tube outside diameter; the inside diameter and wall do not matter to the fitting, only to the flow.
| Thread | Which series carry it | Note |
|---|---|---|
| M3, M5×0.8, M6×1 | mini fittings for 3, 4 and 6 mm tube | M5 is the standard mini pneumatic thread (ISO 16030) |
| G1/8, G1/4, G3/8, G1/2 (parallel, with O-ring or gasket) | most European series | the thread on a cylinder or valve port |
| R1/8, R1/4, R3/8, R1/2 (taper, with sealant) | many Asian series | sold as PT in some catalogues |
| NPT 1/8, 1/4, 3/8, 1/2 | US series | not interchangeable with R |
| 10-32 UNF | US mini fittings | — |
| Metric fine M10×1, M12×1.5, M14×1.5, M22×1.5 | not in the series | sensor, hydraulic and coolant ports; the body is machined |
Push-in, compression or threaded
| Situation | Use | Why |
|---|---|---|
| Air, vacuum or water at moderate pressure, PU / PA / PE tube, fast assembly | push-in | no tools, reusable, the standard pneumatic connection |
| Vibration, oil, or a tube that must not be pulled out by hand | compression fitting | the nut locks the tube mechanically |
| Metal tube, hydraulic pressure | 24° cone or twin-ferrule fitting | push-in does not hold metal tube or high pressure |
| A hose rather than a tube | hose barb | barb and clamp on the hose ID |
| A port thread the push-in series skips | machined push-in body | series collet in a body cut to the thread |
| A wet or washdown line where nickel-plated brass corrodes | stainless push-in body | 304 series where the maker lists it; 316L machined |
What to send for a push-in fitting that is not in the series
- Tube outside diameter and the tube material (PU, PA, PE, PTFE); say whether it is metric or inch.
- Port thread: standard, size and pitch, and whether the port seals on the face (G, metric) or on the thread (R, NPT).
- Form: straight, elbow, tee, union, bulkhead, and any leg length or hex the space needs.
- Body material: nickel-plated brass, 304, 316L; and the medium and pressure if the series limits matter.
- Quantity: from 1 piece.
Identify the thread before you order the push-in fitting. Measure the outside diameter of a male thread, or the inside diameter at the mouth of a female one, with a caliper, and count the threads in 25 mm or in one inch. A G1/4 male measures about 13.2 mm across and has 19 threads per inch; a 1/4 NPT male measures about 13.7 mm and has 18; an M14×1.5 measures 14.0 mm with 1.5 mm between crests. Those three are the ones most often confused on a fitting, and only the metric one is not tapered. Then check whether the thread is parallel or tapered by measuring the diameter at the first and the fifth turn. The fitting thread identification chart lists every common pipe, port and tube thread with its diameter, pitch and seal, and the BSPP vs BSPT note explains the parallel and taper forms of the same BSP size.
Where the push-in series stops
| What you need | In the catalogue? | What we make |
|---|---|---|
| Male straight, elbow, tee or union in a series tube size and a series thread (M5, G, R, NPT 1/8–1/2) | Yes | Buy it from stock, or have the body made to order from 1 piece. No one-off competes on price with a series fitting. Standard parts: ask us too — we may have them in stock. |
| Reducing union, Y, cross, bulkhead, speed controller in series sizes | Yes | Standard sizes: buy it off the shelf, or have it made to order from 1 piece. Standard parts: ask us too — we may have them in stock. |
| A push-in body with a thread the series skips — M12×1.5, M14×1.5, M22×1.5, 3/8 NPT on a 4 mm port, 7/16-20 UNF | No | Body machined in brass or stainless with the series collet, ring and O-ring fitted; from 1 piece. |
| A stud longer than the series, a hex the series lacks, or an elbow leg that clears a housing | No | Machined to the drawing; tube end unchanged. |
| A body in 316L, PEEK or aluminium 6061 / 7075 for a wet, chemical or weight-critical line | No | Machined; the collet and seal chosen for the medium. |
| A tube size between the series — 5 mm, 7 mm, 9 mm, 15 mm | Partly | A collet for that size exists only in some series; otherwise a compression or barb connection is quoted instead, and we say so. |
| A push-in fitting rated for a pressure, temperature or medium the series does not publish | No | Not offered: ratings come from the series maker's data and are not invented for a machined body; we quote a compression or threaded fitting where the data does not exist. |
| A whole manifold with push-in ports | No | Machined from block with series inserts — see fittings and manifolds. |
Materials
| Material | Designation | Where it fits here |
|---|---|---|
| Nickel-plated brass | CW614N / C36000 body, nickel plated | the series push-in body; machined bodies in the same brass |
| Engineering plastic | PBT, POM, PA | series bodies and release rings |
| Stainless 304 | 1.4301 | series stainless push-in fittings in the common sizes |
| Stainless 316L | 1.4404 | machined bodies for washdown and chemical lines |
| Free-machining stainless | 303 / 1.4305 | custom turned bodies where corrosion duty allows |
| Aluminium 6061 | AlMg1SiCu | light machined bodies and manifolds for air and vacuum |
| Aluminium 7075 | AlZn5.5MgCu | machined manifold blocks with push-in ports |
| PEEK | PEEK | bodies for chemical and high-temperature lines |
| Seals | NBR standard; FKM, EPDM on request | O-rings on tube and port |
Related pages
- fitting types chart — every fitting form by ports and standard
- nut-and-ferrule tube fittings — the locked alternative for tube
- through-panel unions — push-in and threaded bulkheads
- non-return valves — one-way push-in and threaded fittings
- male-to-female elbows — elbows without a tube port
- three-port fittings and crosses — tees without a tube port
- Sensor thread adapters — the metric-fine ports push-in bodies are machined for
- Liquid cooling fittings — manifolds with tube ports
Frequently asked questions
None; push-in, push-to-connect and one-touch are three names for the same collet-and-release-ring fitting. Compression or quick-screw fittings are a different family that locks the tube with a nut, and the two are not interchangeable.
Not reliably. 1/4 in tube is 6.35 mm and the collet and O-ring of a 6 mm fitting are sized for 6.0 mm; the joint may hold air at low pressure and let go under load. Metric and inch tube each have their own fitting series, and the tube decides which.
Market aliases used by several makers for male straight (PC), male elbow (PL) and union tee (PE) push-in fittings, with suffixes for tube size and thread. They are not standards and the letters vary by maker, so order by tube outside diameter and thread and treat the code as a description.
Yes. The body is machined in brass, 304, 316L, aluminium or PEEK to the thread and length you specify, and the series collet, release ring and O-ring are fitted, so the tube end is standard. From 1 piece.
EKINSUN LTD is a custom parts manufacturer that machines push-in fitting bodies with any port thread from M5 to G1/2, NPT or metric fine, in brass, 304 / 316L stainless, aluminium 6061 and PEEK, with the series collet fitted, from 1 piece, with a quote within 12 hours.
No list price. Series fittings cost cents in the catalogue; a machined body is priced by material, the thread, any milling, and quantity, plus the series collet. A brass stud body in a metric fine thread is a short lathe job; a 316L elbow body is priced as the machined part it is. The quote separates the series parts from the machined ones.
Send the tube OD and the port thread
Tube outside diameter (metric or inch) and material, port thread standard, size and pitch, form, body material, medium, quantity. From 1 piece, quote within 12 hours.
Not sure of the thread? Tell us four things: what the fitting connects to (pump, valve, gauge, cylinder, tube or hose); whether the port is the inlet or the outlet; which way the flow must go; and the tube outside diameter, not the hose bore, unless it is a barb. A photo with a caliper across the thread answers most of it.