For a coach or bus depot, plan on a 15 to 22 kW screw compressor in its 10 bar version. The S 150 at 10 bar (2.0 m³/min) suits a depot with 4 pits. The S 220 PM (3.2 m³/min at 10 bar) equips a large depot with 6 pits and a tyre bay. Both are variable speed, which matters in a workshop that works in waves.
The needs of a heavy vehicle workshop are set out on our page on compressors for truck workshops. A coach and bus depot has its own features: shifted working hours, a large hall and uses you do not find in a truck garage.
What uses air in a depot
- The maintenance pits: 1 inch impact wrenches for the wheels, ratchets, grease pumps.
- Tyre inflation, around 9 bar according to the tyre manufacturer's tables.
- Blowing: filters, radiators, passenger areas and luggage holds.
- The vehicles' air system. Some workshops supply the air system of a parked coach through the connection provided for this, to check doors or suspension without running the engine. Follow the vehicle manufacturer's instructions, and include this need in the calculation.
- Washing, if the depot has its own gantry: see which compressor for a car wash gantry.
The calculation for 4 pits
We count one mechanic per pit, each with their hungriest tool: the 1 inch impact wrench, about 600 l/min at 6.3 bar as a guide. Check your tools' manuals.
- Gross consumption: 4 × 600 = 2,400 l/min.
- Wrenches work in bursts: they are counted at 50% thanks to the receiver, so 1,200 l/min.
- Safety margin of 25%: 1,200 × 1.25 = 1,500 l/min.
- Expansion margin of 20%: 1,500 × 1.2 = 1,800 l/min.
Tyre inflation requires a 10 bar version. The S 150 delivers 2.0 m³/min at 10 bar, or 2,000 l/min: it covers the 1,800 l/min, expansion margin included.
The calculation for 6 pits
- Gross consumption: 6 × 600 = 3,600 l/min.
- Counted at 50%: 1,800 l/min.
- Safety margin: 1,800 × 1.25 = 2,250 l/min.
- Expansion margin: 2,250 × 1.2 = 2,700 l/min.
The S 220 PM delivers 3.2 m³/min at 10 bar. It leaves about 500 l/min in reserve for blow guns, inflation and the vehicles' air system.
| Depot | Recommended model |
|---|---|
| 2 or 3 pits, no plant room | K 150 at 10 bar, 2.0 m³/min, 340 L receiver, built-in dryer and filtration |
| 4 pits | S 150 at 10 bar, with receiver and refrigerated dryer for 15 kW |
| 6 pits, tyres and blowing | S 220 PM, with receiver and 22 kW dryer |
| Larger depot | Several machines or an industrial project on quotation |
A workshop that works in waves
In a depot, activity follows the service timetable. Coaches come back in the evening, the workshop runs flat out in the evening and at night, then almost nothing while the fleet is on the road. A fixed-speed compressor would spend long hours switching between load and idling. The variable speed of the S and K series matches flow to demand: see variable speed or fixed speed.
During quiet hours, close the main valve or isolate the unused areas. Otherwise the compressor runs just to feed the leaks in the network.
A large hall, a long network
The pits in a depot are often spread along the full length of a hall. Pressure falls with distance, and the last pit gets less than the first. A few rules:
- A ring main balances pressure better than a single dead-end line.
- One drop per pit, taken off the top of the pipe, with a drain at the low point.
- Hose reels and couplings of the right size for 1 inch wrenches.
Our article on a leak-free compressed air network covers the design, and the guide to connecting a compressor to the network covers the connections at the compressor.
The plant room and maintenance
A depot is often in a residential area and works at night. The S 150 and S 220 PM screw compressors are rated at 68 to 72 ± 2 dB(A): install them in a ventilated room, away from neighbours. See the compressor room. They run on 380 V three-phase.
The first service is at 500 hours, then every 1,500 hours. Keep the service kit for your model at the depot: spare parts remain available for 15 years.
Describe your depot (pits, tools, hours) in the configurator, or send us your needs with a quote request.
For your trade: Compressor for truck workshops.