TL;DR — Direct answer: A greenhouse and vertical farm needs clean, dry air at 6 to 7 bar for pneumatic irrigation and nutrient-dosing valves, seeding and transplanting automation, climate-system dampers, and harvest packing lines, with a pressure dew point of 3 degrees C and filtration to 0.01 micron so no oil or moisture reaches a dosing valve, a seeder or a packing head. Size on the coincident peak of irrigation, automation and packing, commonly 3 to 8 cubic metres per minute for a mid-size facility, roughly a 22 to 55 kW screw compressor with a variable speed drive. QiAir, a Chinese screw compressor manufacturer and supplier, builds fixed and variable speed machines with corrosion-resistant treatment for greenhouse and vertical farming operations.
A modern greenhouse or vertical farm is a controlled-environment factory, and compressed air is the muscle behind its automation. Pneumatic valves open and close irrigation and nutrient-dosing lines on a schedule, seeders and transplanters place seedlings with air-driven grippers, climate systems move dampers and vents, and harvest packing lines grade, weigh and box produce. A pressure dip at the wrong moment can leave a dosing valve half open and overwater a crop zone, stall a transplanter mid-cycle, or stop a packing line at harvest peak, when the produce cannot wait. The air system has to be as reliable as the irrigation system it controls. QiAir is a Chinese manufacturer and supplier of screw air compressors, and its machines for greenhouse and vertical farming operations are specified around reliability, humidity tolerance and low maintenance first and flow second.
The mistake buyers make most often is treating a greenhouse like a dry factory. The air is humid, the environment is warm, fertiliser mist is corrosive, and the compressor often sits in a service building that is itself damp. A standard installation that would last years in a dry workshop can corrode in months in a greenhouse. This guide maps where the air goes in a greenhouse and vertical farm, explains how to size for irrigation, automation and packing peaks, sets the humidity and corrosion standard, and shows what to put on a sizing sheet for a China supplier.
Where Air Is Used: Irrigation Valves, Automation, Climate Systems and Packing
Irrigation and nutrient dosing are the most time-critical users. Pneumatic valves control water and nutrient flow to each crop zone, dosing pumps are air-driven, and misting systems use air for fine droplet control. Dosing is scheduled to the minute, so a valve that sticks or opens late changes the water and nutrient balance for a whole zone. Keep the dosing air branch filtered and dry, because moisture in a dosing valve causes sticking and corrosion, and fit a local receiver near the valve manifold if the header run is long, because a local receiver is cheaper than upsizing the whole system.
Automation, climate systems and packing take the rest of the air. Seeders and transplanters use air for grippers and placement, harvesting robots use it for cutting and handling, climate systems use it for damper and vent control, and packing lines use it for grading, weighing, clamping and boxing. Vertical farms add another layer: stacked growing racks mean long air runs to the top levels, where pressure is lowest. A facility that maps every user, including the small air tools used for cleaning, usually finds 15 to 20 percent more demand than the original estimate, and that gap is where pressure problems start.
- Irrigation and dosing: pneumatic valves, dosing pumps and misting systems that run on a strict schedule.
- Automation: seeders, transplanters and harvesting robots that need stable pressure for precise placement.
- Climate and packing: damper and vent control, grading, weighing and boxing at harvest peak.
Sizing for Irrigation Cycles, Automation and Harvest Peaks
List every system with its flow at peak and at steady running, because the two differ sharply in farming work. A mid-size greenhouse or vertical farm with ten to thirty irrigation zones, two to four automation lines and one to two packing lines typically peaks at 3 to 8 cubic metres per minute at 6 to 7 bar, which is roughly a 22 to 55 kW screw compressor, and the peak usually lands at harvest, when packing runs at full load and irrigation is still cycling. A variable speed drive earns its keep here: it follows the irrigation schedule instead of loading and unloading a fixed-speed machine all day, and it holds pressure within the narrow band that dosing valves prefer.
Keep the pressure drop to the farthest valve manifold under 0.3 bar at peak flow, and fit a receiver of 500 to 1000 litres per 10 cubic metres per minute to absorb irrigation and packing spikes. In a vertical farm, run a ring main up the rack levels so the top level is not starved by the bottom. Log pressure at the farthest valve manifold during a full irrigation cycle for a week, because that log is the honest record of whether the compressor is big enough, and it settles arguments faster than any catalogue figure. Never raise the set point to mask a sag: every extra bar adds roughly 7 percent to power use and hides the real fault, which is usually a clogged filter or an undersized pipe.
- Size on the coincident peak of irrigation, automation and packing, not on steady-state average flow.
- Use a variable speed drive for irrigation-schedule loads, and keep far-end pressure drop under 0.3 bar.
- Run a ring main up vertical-farm rack levels, and log farthest-manifold pressure for a week.
Humidity, Fertiliser Mist and Corrosion Protection
Humidity and fertiliser mist are the defining problems of greenhouse air systems. The air is warm and wet, fertiliser mist is corrosive, and a compressor that breathes that air will corrode from the inside. Put the compressor in a dry service building, not inside the greenhouse, and duct the intake to clean, dry air if necessary. Fit a refrigerated dryer to a 3 degree C pressure dew point, a coalescing filter to 0.01 micron and an activated-carbon filter, so no moisture or oil reaches a dosing valve, and use corrosion-resistant piping, stainless fittings and drain legs at every low point, because condensate will form in any line that runs through a cool greenhouse at night.
Reliability matters more here than in most factories, because crops cannot wait for a repair. Fit automatic zero-loss drains, slope lines to drain legs, and test the air at the dosing valve manifold quarterly for oil, moisture and particles. Keep a spare filter set and a spare drain valve on the shelf, check the intake filter weekly in the first months, and keep the compressor room clean, ventilated and dry. If the facility is remote, choose a machine with remote monitoring and a service interval that matches the growing season, so maintenance does not fall at harvest peak.
- Put the compressor in a dry service building, not inside the greenhouse, and duct the intake to clean air.
- Fit full air treatment and corrosion-resistant piping with drain legs at every low point.
- Keep spares on the shelf, check the intake filter weekly, and schedule service outside harvest peak.
Buying from China: Sizing Sheet for a Greenhouse and Vertical Farming Compressor
QiAir is a Chinese manufacturer and supplier of screw air compressors, and a greenhouse or vertical farming order should start with a sizing sheet that names the humidity and the zone layout. Send the supplier the number of irrigation zones, automation lines and packing lines, the coincident peak at 6 to 7 bar, the humidity and ambient temperature in the compressor room, and the distance and height to the farthest valve manifold. Ask for a quotation that states the dryer type and filtration grades explicitly, and ask whether remote monitoring or a second standby machine fits a facility where crops cannot wait for a repair, with the cost spelled out.
Agree the acceptance test before shipment: a full-load run at rated pressure, a dew point reading at the dryer outlet, and a pressure reading at a simulated far-end load. On arrival, install on a level plinth with clear cooler airflow, connect drains before the first run, and survey pressure at the farthest valve manifold during the first full irrigation week. Keep a log of pressure, dew point and filter changes, and review it monthly, because a slow rise in dew point is the earliest sign that a dryer needs attention before dosing valves start sticking.
- Send the supplier irrigation zone, automation and packing line counts, coincident peak and farthest-manifold distance and height.
- Ask for dryer type and filtration grades in writing, and compare a standby machine against remote monitoring on total cost.
- Accept on a full-load test plus dew point and far-end pressure readings, then survey manifold pressure in week one.
Frequently asked questions
What pressure does a greenhouse and vertical farm need?
A greenhouse and vertical farm needs clean, dry air at 6 to 7 bar for irrigation and nutrient-dosing valves, seeding and transplanting automation, climate dampers and packing lines. Keep far-end pressure drop under 0.3 bar, because a pressure dip can leave a dosing valve half open and overwater a crop zone, and size on the coincident peak of irrigation, automation and packing.
Why must greenhouse compressors sit outside the growing area?
Greenhouse air is warm, humid and carries corrosive fertiliser mist, so a compressor inside the growing area corrodes from the inside and its intake filter clogs fast. Put the machine in a dry service building, duct the intake to clean air, fit a refrigerated dryer to a 3 degree C pressure dew point, and use corrosion-resistant piping with drain legs at every low point.
What size screw compressor does a greenhouse and vertical farm need?
A mid-size greenhouse or vertical farm with ten to thirty irrigation zones, two to four automation lines and one to two packing lines typically needs 3 to 8 cubic metres per minute at 6 to 7 bar, roughly a 22 to 55 kW screw compressor with a variable speed drive. Size on the coincident peak of irrigation and harvest packing, and verify pressure at the farthest valve manifold under full load.
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QiAir is a Chinese manufacturer and supplier of screw air compressors. If you are sourcing a screw compressor from China — for a factory, a food plant, a construction site or a new production line — contact QiAir for a sized quotation, documented performance data and export support.