Compressor for car washes

At a car wash, water and chemicals do the visible work, but compressed air runs much of the machinery behind it. On a rollover gantry it drives the cylinders that press and lift the brushes, switches the pneumatic valves and often powers the dosing pumps and the foam generator. On self-service jet wash bays it opens and closes the programme valves and feeds the foam brush or foam lance. At the vacuum stations, the blow gun and the tyre inflator run off the same network. When the compressor stops, the whole site stops with it.

How much air does a car wash need?

Work it out station by station. The figures below are indicative only: the gantry or bay manufacturer's manual gives the exact flow and pressure for its equipment.

• Rollover gantry: around 200 to 300 l/min during a wash cycle (cylinders, valves, foam).
• Jet wash bay: around 30 to 60 l/min per bay for valves and foam.
• Blow gun: about 150 l/min, tyre inflator: about 100 l/min, according to our configurator. Both are used in short bursts, so count them at 50%: the air receiver absorbs the peaks.

Then add a margin of at least 25% for seal wear, the small leaks that are unavoidable in a wet environment, and a future bay.

Example of a typical wash centre: 1 gantry, 4 jet wash bays and 2 vacuum stations with blow gun and inflator.

• Gantry: 250 l/min
• Bays: 4 × 50 = 200 l/min
• Stations: 2 × (150 + 100) × 50% = 250 l/min
• Total: 700 l/min, or about 875 l/min with the 25% margin.

If your gantry manual gives the air demand in another unit, our flow and pressure converter converts l/min to m³/min.

Which compressor for a car wash?

Small site: 2 bays and one vacuum station

With a demand of around 300 l/min including margin, the E 75 piston compressor 7.5 kW is enough: 0.9 m³/min, 180 L receiver, 8 or 12.5 bar. A piston compressor suits intermittent use, which is what a small site with bays that rarely run at the same time looks like. It is also simple to maintain.

A gantry and a few bays: the S 55

Once a gantry runs cycle after cycle all day, demand becomes continuous. The S 55 screw compressor 5.5 kW delivers 0.6 m³/min at 8 bar, or 600 l/min. That is the right size for 1 gantry and 2 bays. It runs at variable speed, matching output to what the site uses, and restarts by itself as soon as pressure drops below the set point. Its noise level of 65 to 68 ± 2 dB(A) helps when the site has neighbours.

Full wash centre: the S 75

For the example above (875 l/min), the S 75 screw compressor 7.5 kW delivers 1.1 m³/min at 8 bar. It is supplied without receiver or dryer: pair it with a receiver sized using our air receiver size calculator and with a dryer. Several gantries or a tunnel wash need more: the S 110 or a project quoted to your needs.

What air quality does a car wash need?

• Water comes first. Every compressor produces condensate. At a car wash, it sticks pneumatic valves, washes the grease out of cylinders and, in winter, can freeze in lines that run outdoors or under the gantry. An air dryer after the receiver is essential. A refrigerated dryer is fine if the whole network stays in a heated room; if some lines are exposed to frost, a desiccant dryer reaches a much lower dew point. Our article which air dryer to choose compares the two.
• Oil. Our compressors are oil-lubricated. For the blow gun used on paintwork and glass, add fine filters, including a coalescing filter that captures oil aerosols.
• Air class. Our technicians help you define the right air class under ISO 8573-1, explained in our compressed air quality guide.

Installation and maintenance

• The room. Install the compressor in a closed plant room, frost-free, ventilated and protected from water spray and chemical fumes. Our article on compressor room installation sets out the basics.
• Draining. Car washes often run unattended, so an automatic condensate drain avoids missed drains. Condensate contains oil: route it through an oil/water separator before discharge, in line with local regulations. Our article on water in compressed air covers every drain point.
• Servicing. On the S 55 and S 75, the first service is at 500 hours, then every 1,500 hours, with a reminder on the controller. Our service kits bundle the filters and wear parts for each model. On a piston compressor, the usual rule of thumb is an oil change about every 500 hours and at least once a year. Our technicians and partner dealers can also take care of maintenance and inspections.

AIRSTAHL compressors carry a 2-year warranty, with spare parts available for 15 years.

To size your site, use the configurator or the air receiver size calculator, then send us your list of gantries and bays in a quote request.

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