In a garage, a good air system comes down to one rule: a main line running round the workshop, one drop per lift and per fixed workstation, and a hose reel at each drop. The main line must carry the total need of the garage, each drop only the hungriest tool at that station.
Choosing the compressor itself is covered on our compressor for garages page. Here we deal with everything between the compressor outlet and the impact wrench.
1. Start from the workshop plan
Draw the garage from above and mark:
- the compressor, in a ventilated room or corner, away from reception if it is a piston unit;
- each vehicle lift;
- the tyre station (tyre changer, wheel balancer, inflator);
- the workbench and parts cleaning area, which use the blow gun.
Each point of use gets its own drop. The main line links the compressor to all the drops, ideally as a ring round the workshop: air then arrives from both sides and pressure stays more even at the last lift.
2. Work out the flow of each section
Typical figures, to check against the manuals: 1/2" impact wrench about 300 l/min, tyre changer about 150 l/min at 8 bar, blow gun about 150 l/min.
The main line. It carries the need of the whole garage. For 3 lifts: three impact wrenches counted at 50% thanks to the receiver, so 3 × 150 = 450 l/min, plus a 25% margin, so about 570 l/min.
A lift drop. It only supplies one mechanic, but while the wrench is turning it really draws 300 l/min. The drop is sized on this instant flow, not on the average.
A truck bay drop. A 1" impact wrench uses around 600 l/min. If a bay takes trucks, its drop and hose reel must handle that flow, as we explain in which compressor for a 1 inch impact wrench.
The pipe diameter depends on this flow and on the length of the main line. The rules for choosing the pipe and the route are set out in our article on a leak-free compressed air network. If your manuals give flows in cfm or m³/h, the flow and pressure converter does the conversion.
3. Place the drops and hose reels
- One drop per lift, on the nearest wall or column, with the outlet at chest height. Two mechanics sharing one outlet end up dragging a hose across the next lift.
- A hose reel above each lift, mounted high enough that the hose does not get in the way of the lift arms or of vehicles driving in. It takes the hose back up after each job.
- A reel hose just long enough to reach all four wheels of the vehicle. Every extra metre and every undersized bore lowers the pressure at the wrench.
- A shut-off valve at the top of each drop, to isolate a leaking reel without shutting down the whole garage.
4. Quick couplings: one profile across the garage
Mixing quick coupling profiles is a classic trap: a tool that will not fit the next reel, or an adaptor that adds a leak and a restriction. Choose one profile, then fit all tools, reels and drops with it. Also choose a bore suited to the 300 l/min of an impact wrench: an undersized coupling starves the tool even with a large compressor. See our quick couplings.
5. Deal with water before it reaches the tools
- Take air off the top of the main line with a swan neck outlet, so water does not run down into the hose reel.
- Fit a drain at the low point of each drop. It collects the water that would otherwise end up in the impact wrench.
- Drain the compressor receiver, or fit an automatic condensate drain.
- Keep the lubricator separate. Tool oil goes as close to the tool as possible, never upstream of an outlet that also serves tyre inflation or a spray gun.
With a 4-in-1 compressor such as the K 75, air already leaves dried and filtered: the network connects straight to its G 3/4" outlet, through a flexible connection hose that absorbs vibration. On a piston compressor such as the E 75, the full sequence of receiver, dryer and filters is described in our guide to connecting a compressor to the air network.
6. Test the system in the evening
Once the system is in place, run a simple test: at the end of the day, with tools disconnected, let the compressor reach its pressure, switch it off and note the gauge reading. If it has dropped noticeably by the next morning, there is a leak. Close the drop valves one by one to find the branch at fault. Our article on compressed air leaks gives the full method.
To check the flow your network must carry, list your tools in the configurator, or send the plan of your garage with a quote request.
For your trade: Compressor for garages.