A wide-nozzle drying blow gun uses around 250 to 400 l/min. To finish a vehicle after washing, drying the seals, mirrors, grille, wheels and badges, allow around 3 to 8 minutes of blowing, or about 1,000 to 2,500 litres of free air per car. For a hand car wash drying ten to twenty vehicles a day with one or two blow guns, an S 55 screw compressor (600 l/min at 8 bar) or a K 75 (1.1 m³/min) is enough, provided you do not dry the whole bodywork with compressed air.
The page compressor for car detailing presents all the tools of the trade. Here, we put figures on drying.
Why dry with compressed air?
After rinsing, water hides in everything that is not smooth: door and boot seals, mirror housings, grille slats, wheel nuts and spokes, badges, chrome trims. A microfibre towel cannot reach it. If you leave it, it runs down the dry bodywork a few minutes later and leaves streaks, or limescale marks on dark paint. A jet of air drives this water out in a few seconds, without contact, so with no risk of scratching.
On large flat panels, on the other hand, compressed air is a poor choice: it takes a lot of air to move a film of water, and the narrow nozzle forces slow passes. A microfibre drying towel or an electric turbine blower, which moves a large volume of air at low pressure, is faster and more economical there.
How much air does it take to dry a car?
Indicative figures, to adjust to your blow gun (see its manual) and your way of working:
| Area | Indicative blowing time |
|---|---|
| Door, boot and bonnet seals | 1 to 2 min |
| Mirrors, handles, badges | 30 s to 1 min |
| Grille and air intakes | 30 s to 1 min |
| Four wheels | 1 to 3 min |
| Trims, wipers, fuel flap | 30 s to 1 min |
| Total | around 3 to 8 min |
Calculation for one vehicle, with a drying blow gun at 300 l/min and 6 minutes of blowing: 300 × 6 = 1,800 litres of free air, or 1.8 m³.
Calculation for one day at a site that dries 15 vehicles: 15 × 1.8 = 27 m³ of air. An S 55 producing 0.6 m³/min supplies this volume in 27 ÷ 0.6 = 45 minutes of combined running over the day. So drying does not size the compressor through the total volume, but through the instantaneous flow when several blow guns run at the same time.
To estimate the matching electricity use, our compressor electricity cost tool starts from the power and the operating hours.
Which compressor for drying?
Size on instantaneous flow, with the margins from our configurator: 25% for safety and 20% for expansion.
One drying blow gun on its own, used for long periods and counted in full to be safe: 300 × 1.25 × 1.2 = 450 l/min. The S 55 (600 l/min) or the E 75 (900 l/min, 180 L air receiver) are suitable.
One drying blow gun and one tornado-type air cleaning gun at the same time, as in a studio where one person finishes the exterior while the other does the interior: (300 + 350) × 1.25 × 1.2 = 975 l/min. The K 75 (1,100 l/min at 8 bar) covers this need.
Two drying blow guns running continuously: 2 × 300 × 1.5 = 900 l/min, still within the K 75's range.
If your business includes high-pressure wash bays or a gantry, add their consumption: see our page compressor for car washes and the article how much air for a car wash.
How can you use less air for drying?
- Dry the bulk with a microfibre towel or an electric blower, and keep compressed air for the nooks and crannies. This is the biggest saving.
- Choose the right nozzle. A venturi or multi-hole nozzle draws in surrounding air and moves more water for the same compressed air flow than an open pipe. Our article on blow-off nozzle consumption compares the types.
- Lower the pressure at the bay. Between 4 and 6 bar is often enough to drive the water out: a regulator at the bay limits consumption.
- Get rid of leaks. Worn quick couplings, crushed hoses: a damp workshop multiplies them. See how to detect and repair leaks.
- Choose variable speed. The S and K series slow down between two cars instead of running idle.
Dry air, so you dry without marking again
A common paradox: a blow gun that spits out condensed water marks the bodywork it was meant to dry, and leaves greasy drops on the glass. Our compressors are lubricated; a refrigerated dryer at the compressor outlet, an automatic drain and fine filters at the bay solve the problem. The K 75 has a built-in dryer and filtration. If the air or the pipes are exposed to cold, read our article on the car wash air dryer in winter.
Common mistakes at the drying bay
- Blowing the whole bodywork. This is what makes consumption soar: ten minutes of blow gun at 300 l/min is 3,000 litres of air for a result a microfibre towel achieves faster.
- Using a standard blow gun. A workshop blow gun with a small nozzle, at around 150 l/min, means spending a long time on every seal. A wider drying nozzle drives the water out in one pass.
- Aiming too close. At a few centimetres, the jet can lift dust out of a seal and throw it onto clean paint. Keep about ten centimetres away.
- Forgetting the hoses. A hose that is too narrow drops the pressure at the end of the nozzle: drying takes longer and uses more air.
Where should the compressor go?
Not in the wash area. Water spray and air saturated with moisture damage the motor and overload the dryer. Install the compressor in a dry, ventilated room, and bring the air through a pipe to a hose reel at the drying bay. Our article on the compressor room sets out the installation rules. Screw compressors are serviced at 500 hours, then every 1,500 hours.
To size your installation, enter your blow guns and tools in the configurator, or send us your set-up with a quote request.
For your trade: Compressor for car detailing and valeting.