In most workshops, a good share of the air produced by the compressor escapes through leaks. Finding and fixing them is worthwhile: we explain how in Compressed air leaks: how to detect and repair them. But the most effective approach is not to create them in the first place. A well-designed, well-installed network stays airtight for years. Here is the method, from design to the final test.
1. Fewer fittings, fewer leaks
Every fitting, every valve, every coupling is a potential leak. The first design rule is therefore simple: make the network as short and simple as possible.
- Place the compressor as close as possible to the stations that use the most air.
- Prefer long straight runs of pipe to a succession of short pieces.
- Remove dead legs: a pipe that no longer serves anything is a leak waiting to happen.
- Keep the number of quick couplers to what is strictly necessary, and group them by workstation.
2. Choosing the right pipe
The network material largely determines how airtight it stays over time.
| Material | Strengths | Points to watch |
|---|---|---|
| Aluminium (push-fit systems) | Light, does not rust, quick to install, airtight fittings designed for compressed air, easy to modify | Higher purchase price, use fittings from the same system |
| Stainless steel | Does not rust, very durable | Expensive, installed by a professional |
| Engineering plastic rated for compressed air | Economical, does not rust | Only a product certified for compressed air, respect maximum pressure and temperature, protect from impacts |
| Threaded galvanised steel | Robust, familiar | Rusts from the inside with condensate water, many threads and therefore many potential leaks |
| Copper | Durable, does not rust | Careful brazing essential, cost |
For a new workshop or a refurbishment, aluminium push-fit systems are now the most common choice: they are designed for compressed air, and their fittings stay airtight without threading or brazing. Never use PVC pipe intended for water: it is not designed for pressurised air and can burst.
3. Sizing so the system doesn't strain
A pipe that is too small causes a pressure drop. To compensate, the compressor pressure gets turned up, which increases the flow lost through every leak. A properly sized network lets you work at a lower pressure, and therefore leak less.
- Size the diameter according to the compressor's flow rate and the total length of the network, allowing a margin for future needs.
- Aim for a low pressure drop between the compressor and the furthest workstation.
To work out the pressure you actually need, read Bar and pressure: how to calculate the pressure you need.
4. The layout: ring main, slope and branch connections
- A closed ring main around the workshop rather than a dead-end line: air reaches the workstations from both sides, and pressure stays more stable.
- A slight slope in the direction of air flow (around 1 to 2%), with a drain point at the low point. Condensate water does not sit in the pipes, and seals age more slowly.
- Branch connections taken from the top of the main pipe, in a swan-neck shape. Water stays in the main pipe instead of running down to the tools.
- Isolation valves for each zone: you can work on part of the network without shutting everything down, and isolate a zone overnight.
The order of components at the compressor outlet (receiver, dryer, filters) is covered in our guide Connecting your compressor to the workshop air network.
5. Fittings and sealing: the right techniques
Most leaks are decided at installation.
- Cut square and deburr every pipe: a crooked cut or a burr damages the fitting's seal.
- Use a single fitting system throughout the network, and do not mix brands.
- On threads, use a sealant suitable for compressed air (paste or resin intended for this use) or PTFE tape wound in the right direction, without excess. Loose bits of tape end up in valves and tools.
- Tighten to the correct torque, without forcing: an overtightened fitting cracks or crushes its seal.
- Support the pipes with evenly spaced clamps: a pipe that sags or vibrates puts strain on its fittings.
- Connect the compressor to the network with a flexible hose, so that machine vibrations are not passed into the rigid pipework.
6. The weak points at the end of the line
Leaks rarely occur on the pipes themselves. They are mostly at the ends:
- Couplings and quick couplers: choose good quality and replace them as soon as they hiss.
- Hoses: avoid excessive lengths that drag on the floor and get crushed; reels and holders extend their life.
- Filters, regulators and lubricators: check the bowls and seals.
- Drains: a drain stuck open blows air continuously.
7. Testing before commissioning
A new network is tested before the tools are connected.
- Bring the network up to pressure with all outlets closed.
- Stop the compressor and isolate it from the network.
- Note the pressure on a gauge, then wait without using anything.
- If the pressure drops, look for the leak fitting by fitting with a leak detection spray or soapy water.
Keep a record of the starting pressure and the test duration: repeating the same test every year shows straight away whether the network is deteriorating.
8. Keeping a network airtight over time
- A regular inspection round, with the workshop shut down, when it is quiet enough to hear hissing.
- A tag on every leak found, and a prompt repair.
- The compressor switched off or the network isolated overnight and at weekends.
- A dryer and drains in good working order: dry air is much kinder to seals. To choose one, read Which air dryer should you choose?.
Your AIRSTAHL installation
An airtight network lets a properly sized compressor work less and last longer. If you are planning an installation or a network extension, send us the workshop layout, the tools used and the distances: we will help you choose the right compressor, dryer and connection components.