Pneumatic fittings are the connectors that join tubing to valves, cylinders, regulators and other components in a compressed air system. Choosing the wrong fitting type leads to leaks, pressure drops and costly downtime. This guide covers the most common pneumatic fitting types and how to select the right one for your application.
Push-In Fittings (Push-to-Connect)
Push-in fittings are the most popular choice in modern pneumatic systems. You insert the tube into the fitting body and a collet with stainless steel teeth grips it instantly — no tools required. To release the tube you simply press the collet release ring and pull.
Push-in fittings are available in straight, elbow (90°), T-piece, Y-piece, bulkhead and many other configurations. They accept round polyurethane (PU), nylon (PA) or polyethylene (PE) tubing in standard metric sizes from 4mm to 16mm OD.
Key advantages: quick assembly, easy tube changes during commissioning, and a clean professional appearance. The main limitation is that they are not suitable for metal tube or irregular tube profiles.
Compression Fittings
Compression fittings use a ferrule and nut that compress around the tube to form a seal. They require a spanner to tighten and are therefore slower to assemble but form an extremely robust connection resistant to vibration and pressure fluctuation.
Stainless steel and brass compression fittings are widely used in hydraulic, high-pressure pneumatic and instrumentation applications. They are compatible with both plastic and metal tube. If your system runs above 10 bar or in environments with high vibration, compression fittings are usually the safer choice.
Threaded Fittings: BSP and NPT
Many pneumatic components — valves, cylinders, pressure gauges — have threaded ports. The two thread standards you will encounter most are:
- BSP (British Standard Pipe) — dominant in the UK and Europe. BSPP (parallel) and BSPT (tapered) variants exist. BSPP relies on a face seal or bonded washer; BSPT seals on the thread itself with PTFE tape.
- NPT (National Pipe Thread) — the US standard, tapered thread. Not interchangeable with BSP despite similar sizes.
Always confirm the thread standard before ordering adapters. A common mistake is purchasing an NPT fitting for a BSP port — they appear similar but leak.
Banjo Fittings
Banjo fittings allow fluid or air to pass through a bolt and into a component at a right angle. They are common in compact assemblies where a conventional elbow fitting would not fit. The bolt passes through the component body and a ring-shaped fitting (“banjo”) with sealing washers on each side.
How to Choose the Right Pneumatic Fitting
Work through these questions:
- What tube type and OD are you using? Metric OD push-in fittings will not work on imperial tubing.
- What is the working pressure? Push-in fittings are typically rated to 10–16 bar. Above this, use compression or bite-type fittings.
- What is the operating temperature? Standard PU push-in fittings handle -20°C to +60°C. Higher temperatures require nylon tube and appropriate fittings.
- What is the thread standard on the component port? Measure carefully or consult the component datasheet.
- How often will you disconnect this joint? Push-in fittings are designed for many connect/disconnect cycles; compression fittings less so.
Browse our full range of pneumatic fittings and accessories including push-in, compression and BSP threaded connectors from leading brands.
Frequently Asked Questions
What is the difference between push-in and compression pneumatic fittings?
Push-in fittings use a collet to grip the tube instantly without tools u2014 ideal for quick assembly and frequent disconnection. Compression fittings use a ferrule tightened by a nut to form a robust seal suited to high pressure, vibration and permanent connections.
Are BSP and NPT threads interchangeable?
No. BSP and NPT threads are not interchangeable despite appearing similar. They have different thread angles (55u00b0 for BSP, 60u00b0 for NPT) and will not seal properly if mixed. Always check the thread standard on your component before ordering fittings.
What tube size do I need for push-in pneumatic fittings?
Push-in fittings are sized by the outside diameter (OD) of the tube. Common metric sizes are 4mm, 6mm, 8mm, 10mm and 12mm OD. Make sure you measure the outside diameter of your tube, not the inside diameter, when selecting fittings.
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