Which pipe should I use for compressed air?
Which pipe should I use for compressed air?
Copper, steel, stainless or a purpose-rated aluminium or HDPE air system — never PVC, which fails explosively.
This is one of the few entries where a common practice is outright dangerous. PVC pipe is rated for liquids, not gases, and the distinction matters because a liquid is nearly incompressible: a burst water pipe releases its pressure almost instantly, while a burst air line releases the stored energy of the whole compressed volume at once. PVC also fails in a brittle mode rather than by tearing, so it shatters into fragments, and it is progressively embrittled by the oil mist carried over from a piston compressor. Pipe manufacturers state explicitly that their PVC is not for compressed air, and workplace safety bodies have issued specific warnings after injuries. Metal or a system certified for air is the only reasonable choice.
The options, ranked
| Option | Good at | Bad at |
|---|---|---|
| Purpose-made aluminium air pipe | Push-fit modular systems, smooth bore, no corrosion, and rated and certified for compressed air. | Expensive compared with improvised alternatives. |
| Copper | Readily available, easy to work, corrosion-free and entirely suitable for shop air pressures. | Cost, and soldered joints need to be done properly. |
| Black iron or steel | Strong, cheap and traditional for workshop ring mains. | Rusts inside, and the scale ends up in tools and paint work unless there is good filtration. |
| PVC pipe | Nothing. It is cheap and it looks tidy, which is why people use it. | It fails by shattering rather than splitting, throwing sharp fragments, and it embrittles further with age and compressor oil. |
Technique that changes the outcome
- Use metal or a certified compressed-air system, and check the pressure rating at temperature
- Slope the ring main slightly and take drops off the top of the pipe so condensate does not run into tools
- Fit drain legs at low points and a filter or dryer before any tool or spray equipment
- Fit a shut-off valve and a regulator at each drop
What goes wrong
- PVC or CPVC pipe for compressed air, in any circumstances
- Reusing gas or water hose not rated for the pressure
- Taking a drop off the bottom of a horizontal run, which feeds water straight into the tool
Compiled practical guidance rather than a published standard. Product formulations vary by brand and market, so read the label — and where the work is structural, electrical or gas, the regulations that apply where you are govern rather than anything here.
Other pipe questions
| For | Use |
|---|---|
| Hot and cold water | Copper or PEX for most installations — PEX is faster and more freeze-tolerant, copper is more robust and takes heat without question. |
| Waste and drainage | Solvent-weld or push-fit PVC-u or polypropylene, at the right diameter and fall — and ABS and PVC cements are not interchangeable. |
| Central heating | Copper, or a barrier-grade plastic pipe — non-barrier plastic lets oxygen into the system and corrodes it from the inside. |
| Boiler condensate | Plastic, never copper, at a generous diameter with continuous fall — and insulate any external run, because frozen condensate is the classic winter breakdown. |
| Gas | Steel, copper of the right grade, or yellow MDPE underground — and in most jurisdictions only a registered installer may do the work. |
| An underground water supply | Blue MDPE for potable water, in one continuous length at the required depth, with no joints under a building. |
| Irrigation | Low-density polyethylene tubing with barbed fittings for drip lines, and PVC or MDPE for buried mains. |
Common questions
- Which pipe should I use for compressed air?
- Copper, steel, stainless or a purpose-rated aluminium or HDPE air system — never PVC, which fails explosively.
- What should I avoid?
- PVC or CPVC pipe for compressed air, in any circumstances Reusing gas or water hose not rated for the pressure Taking a drop off the bottom of a horizontal run, which feeds water straight into the tool
Related pages
- Which pipe should I use for hot and cold water? Copper or PEX for most installations — PEX is faster and more freeze-tolerant, copper is more robust and takes heat without question.
- Which pipe should I use for waste and drainage? Solvent-weld or push-fit PVC-u or polypropylene, at the right diameter and fall — and ABS and PVC cements are not interchangeable.
- Which pipe should I use for central heating? Copper, or a barrier-grade plastic pipe — non-barrier plastic lets oxygen into the system and corrodes it from the inside.
- Which pipe should I use for a boiler condensate drain? Plastic, never copper, at a generous diameter with continuous fall — and insulate any external run, because frozen condensate is the classic winter breakdown.
- Which pipe is used for gas? Steel, copper of the right grade, or yellow MDPE underground — and in most jurisdictions only a registered installer may do the work.
- Which pipe should I use for a buried water supply? Blue MDPE for potable water, in one continuous length at the required depth, with no joints under a building.
- Which pipe should I use for irrigation? Low-density polyethylene tubing with barbed fittings for drip lines, and PVC or MDPE for buried mains.
Sources
- Typical range compiled from manufacturer specifications — At One Place