Two of the most common ways to join pneumatic tube are push-in fittings and compression fittings. Both do the same basic job of connecting tube to a port or to another length of tube, but they suit different situations, and choosing the wrong one usually shows up later as a leak or a joint that is a pain to service. This guide walks through how each type works and when to reach for one over the other.
How Push-In Fittings Work
A push-in fitting, sometimes called push to connect, grips the tube with a stainless steel collet and seals it with an O ring. You cut the tube square, push it in until it stops, and the collet bites to hold it against the pressure. To release it you press the collet ring in and pull the tube out. There is no tightening and no tools, and you can reuse the fitting many times, which is why they dominate control panels and any job with a lot of connections. We carry a large push-in fittings range in metric and imperial sizes.
How Compression Fittings Work
A compression fitting seals differently. The tube passes through a nut and a ferrule or olive, and as you tighten the nut the ferrule is squeezed onto the tube to form the seal. It takes a spanner and a little more time, but the result is a solid, permanent joint that handles higher pressure and stands up to vibration and temperature better than a push fit. These are the fittings you want on hard nylon tube, on longer runs, and anywhere the connection needs to stay put for years. Our adaptors and compression fittings section covers brass and other options across the common sizes.
Speed Versus Permanence
The honest way to choose is to think about how often the joint will be touched. If you are wiring up a machine with dozens of connections that might be reworked during commissioning, push-in wins every time because you can make and break joints in seconds. If you are running a fixed line that will be pressurised and then forgotten, a compression fitting gives you a joint you can trust and rarely need to revisit. Plenty of systems use both, push-in at the actuators and valves where things change, and compression on the main runs where they do not.
Pressure, Tube and Temperature
Push-in fittings are happiest on soft tube such as polyurethane and nylon within their rated pressure, typically up to around 10 to 16 bar depending on the range. Compression fittings cope with higher pressures and firmer tube, and they tolerate heat and vibration that can eventually work a push fit loose. Whichever you use, the tube has to match the fitting. Match the outside diameter, keep metric and imperial apart because 6mm and 1/4 inch are close but not the same, and always cut the tube square so the seal grips cleanly.
A Quick Rule of Thumb
For fast, reworkable, lower pressure work, fit push-in. For permanent, higher pressure or high vibration work, fit compression. If a job sits in the middle, think about who will maintain it and how often. If you are still weighing it up, our engineers size fittings all day and can talk it through, and because we hold both types in UK stock you are not stuck waiting on a manufacturer to make a decision. Browse the push-in fittings and compression fittings ranges, or call 01474 334537.
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