For a greenhouse with a potting machine and a small seeding line, a screw compressor of 0.6 to 1.1 m³/min is often enough: the S 55 with a dryer, or the K 75 4-in-1, which has the tank, dryer and filtration built in. The real issue is not power but humidity: greenhouse air is warm and full of water, and the compressor must be installed somewhere else.
The rest of a farm's air needs are covered on our page on the compressor for agriculture. Here we look at the greenhouse and its machines.
What is compressed air used for in a greenhouse?
Depending on the equipment, compressed air drives:
- potting machines and pot fillers, with their cylinders and valves;
- seeding and transplanting lines, their grippers and stops;
- tray and pot destackers, which work in pulses;
- blowing trays, trolleys and benches clean;
- maintenance tools for the structures and benches.
Some seeders work by suction, with a vacuum pump rather than compressed air. Check the manual: a compressor does not cover that need.
The calculation, step by step
Step 1, the machine data sheets. The manufacturer gives the air consumption, in l/min or in litres per cycle, and the working pressure. If the sheet gives litres per cycle, multiply by the number of cycles per minute. For a cylinder-driven machine with no data sheet, our article on pneumatic cylinder air consumption gives the formula.
Step 2, what runs at the same time. In the middle of the potting season, the potting machine, the seeding line and the destacker often run together. Add them up. Hand tools are counted at 50%.
Step 3, the margin. Add 25%.
Example of a greenhouse in full season (figures for guidance only, replace them with those from your data sheets):
- potting machine: 150 l/min
- seeding line: 100 l/min
- tray destacker: 50 l/min
- blow gun, used in bursts: 150 l/min counted at 50% = 75 l/min
- total: 375 l/min, or about 470 l/min with the margin
Which model to choose?
| Situation | Model |
|---|---|
| One potting machine and one line, running for hours in season | S 55, 0.6 m³/min at 8 bar, with an air receiver and a dryer |
| Several lines, or a simple installation | K 75, 1.1 m³/min at 8 bar, 420 L tank, dryer and filtration built in |
| Blowing and tools only, a few minutes a day | E 75, 0.9 m³/min, 180 L tank, with a dryer |
Greenhouse machines run in seasons and often stop between two batches. A variable speed screw compressor slows down when demand drops: our article variable or fixed speed explains what that changes.
Humidity, the number one pitfall
- Do not put the compressor in the greenhouse. It would draw in warm, saturated air that then has to be dried. Install it in a dry, ventilated room, away from irrigation. Our article on the compressor room sets out the rules.
- Dry the air. Water in the pipes makes cylinders stick and valves rust. A refrigerated dryer after the compressor is the basis: our article which air dryer to choose compares the options.
- Watch the pipes that run through the greenhouse. If the air cools at night in a pipe colder than the dryer outlet, water condenses again. Fit a drain point at the bottom of every drop.
- Summer heat. The compressor room must not turn into an oven. See our article on the compressor in a 35 °C workshop.
Condensate and irrigation water
Our compressors are lubricated: the condensate contains oil. Do not send it into rainwater collection tanks or the irrigation circuit. An automatic condensate drain connected to an oil-water separator deals with it. If the air blows directly onto plants or growing media, add fine filters at the point of use.
The spring peak
If one potting season far exceeds the rest of the year, keep a compressor sized for the everyday need and top it up during the peak with a rental compressor: we rent screw compressors from 5.5 to 132 kW, with maintenance included.
For your greenhouse, enter your machines in the configurator, then send us their data sheets with a quote request.
For your trade: Compressor for agriculture.