Airline, hose, pipe or tube, its all the same thing – air suspension airline. It’s purpose is to transfer the air from where its generated to the bags, and then back to the atmosphere.
Whilst metal lines do exist these tend to be limited to hot lines where the air is compressed, struts which turn and for cosmetic reasons on show builds. In this case metal lines and braided lines are limited to just near the compressor, where it can be seen in the boot, or Air Lift still use braided lines on their front struts. Metal lines are not used as a matter of course for the entire air suspension build on a modified car, van or motorhome, and not for OEM air suspensions either, because they serve no purpose. Metal lines are more expensive to buy, more work to install, offer no benefits in terms of durability or reliability (they often actually seal less well due to lack of flexibility and a mixture of unsuitable materials).
Air suspension systems tend to use plastic lines. They are either Nylon or Polyurethane. At AirRide we prefer nylon and that’s all we use on our own systems. Polyurethane is a little softer and more prone to damage. Nylon is easily kinked during installation if you are not careful, but more durable for the rest of its life. Just in case you think nylon isn’t strong enough – the end caps on most modern bags are made of nylon, so the whole weight of your car or van can rest on this material!!
So what about sizes?
Well there are a number of sizes in use, but in general OEM systems tend to run 4mm, 5mm, and 6mm. Sometimes a combination using for example 4mm in places and 6mm in others. On OEM’s the size is usually not written on the line, but it can be sometimes, so its still worth looking if you need to replace a line.
For aftermarket systems, some of the smaller European suppliers do use metric (6mm and 8mm) but in general the world supply of aftermarket air suspension systems tends to use 1/4 and, 3/8 as the most common sizes with 1/8 and 1/2 can also be used in places. This is because the market for management, tanks, compressors, and controllers is dominated by the US where the industry started, and they use imperial measurements. Sizes larger than this would be very rare due to the dangers of injury due to the high speed of vehicle adjustment (danger to people and vehicle integrity). Most line will have the size written on it which makes life easier although some will not. All the line we use is rated for over 200psi, because that's what our common high spec systems are rated to.
Because of the fact that metric and imperial sizes can be close you are not going to be able to measure with a ruler, or guess by just looking, although a tip is to look at the push connector fittings, as many will have the size written (very small on the collar). Failing that you will need a vernier calliper, either digital or analogue to measure.
If in doubt and you need help identifying your requirements please call us on 0800 772 0315 or send an email to ENQUIRIES@AIRRIDE.UK