A pneumatic ironing press uses around 100 to 300 l/min while it runs cycle after cycle, at a working pressure of 5 to 6 bar. A single press can be supplied by a 5.5 kW screw compressor such as the S 55 (0.6 m³/min at 8 bar). From two presses working together, with a form finisher and spotting alongside, a 7.5 kW 4-in-1 such as the K 75 (1.1 m³/min) is the right starting point.
The air needs of the whole shop are set out on our page compressor for dry cleaners. Here, we focus on the press.
How does a pneumatic ironing press work?
On a pneumatic press, the head is not closed by hand or by a spring-loaded lever. One or two cylinders lower it onto the buck when the operator presses the controls, hold it closed while the steam passes through, then raise it again. Depending on the model, other cylinders operate:
- the locking of the head in the closed position;
- the clamps that hold the collar, the cuffs or the trouser hem;
- the rotating or sliding buck on double-buck presses;
- the steam and vacuum valves, on some presses.
The steam itself comes from the steam generator. The compressor only supplies the air for the cylinders and valves.
How much air does a press use?
The manual gives either a consumption in l/min or a volume per cycle. The figures below are orders of magnitude and are indicative only.
| Type of press | Consumption of around | Usual working pressure |
|---|---|---|
| Utility press | 150 to 250 l/min | 5 to 6 bar |
| Collar and cuff press | 100 to 200 l/min | 5 to 6 bar |
| Trouser press or topper | 50 to 100 l/min | 5 to 6 bar |
| Double-buck rotary press | 200 to 300 l/min | 6 bar |
Going from litres per cycle to l/min
If the manual gives a volume per cycle, the calculation is simple:
- Air volume per cycle, for example 20 litres of free air.
- Number of cycles per minute at busy times: a fast operator closes the press about once every 10 seconds, so 6 cycles per minute.
- Consumption: 20 × 6 = 120 l/min.
Take the rate at peak times, not the average over the day. That is when the pressure is most likely to drop.
What pressure for an ironing press?
Most presses need 5 to 6 bar at the inlet. Below that, the head closes weakly, the crease is less sharp and some presses refuse to lock.
Set the compressor at 8 bar. Between the compressor and the press, the dryer, the filters and the pipework cost some pressure, and the press regulator needs a small reserve to do its job. There is no point going higher: every extra bar increases leaks around the hoses and quick couplings, of which a pressing room has plenty. Our article how to calculate compressor pressure explains this reasoning in detail.
The calculation for a shop with several presses
Several presses do not close at exactly the same moment, but at busy times they are all running. So they are counted at 100%. Form finishers, toppers and spotting guns, used intermittently, are counted at 50%.
Example of a dry cleaner with a shirt service (indicative figures):
- Utility press: 200 l/min.
- Collar and cuff press: 150 l/min.
- Topper: 80 l/min, counted at 50%, so 40 l/min.
- Spotting gun: 120 l/min, counted at 50%, so 60 l/min.
- Valves on the dry cleaning machine: 50 l/min.
- Total: 500 l/min.
- With a 25% safety margin: 625 l/min.
- With 20% for one more machine: 750 l/min, or 0.75 m³/min.
The K 75 delivers 1.1 m³/min at 8 bar: it covers this need with reserve to spare. The S 55, at 0.6 m³/min, would be too tight here. For a central plant with three or more presses, the K 110 delivers 1.7 m³/min at 8 bar.
What size of air receiver for the presses?
Presses use air in waves: several closures in quick succession, then a pause while the operator repositions the garment. The air receiver absorbs these waves and lets the variable speed compressor slow down in between. The K 75 has a 420 L air receiver, the K 110 a 340 L air receiver. With an S 55, plan for a separate air receiver: our air receiver size calculator gives the volume for your needs.
Air quality for the press
Most presses only need dry air for their cylinders. But some blow or draw air through the buck, and the exhaust air from the cylinders can come out close to the garments. Air that is damp or carries oil will then end up marking the buck padding, and after that the clothes. A refrigerated dryer and a fine filter at the compressor outlet solve the problem. Our article stains on garments at the dry cleaner's covers the causes and the remedies.
Signs that the compressor is too small
- The head closes less firmly towards the end of the morning: the pressure is dropping at busy times.
- The press pressure gauge falls below 5 bar every time it closes.
- The compressor never stops at busy times. Our article compressor that runs constantly helps you find the cause, which may also be a leak.
- Leaks. A fitting hissing behind a press can use as much air as a topper. Our article detecting and repairing leaks gives the method.
To size your compressor, enter your presses in the configurator, then send their manuals with a quote request.
For your trade: Compressor for dry cleaners and dry cleaning shops.