TL;DR — Direct answer: Tea processing needs clean dry air at 7 to 8 bar for withering, rolling, drying, sorting and packing, with a pressure dew point of 3 degrees C and filtration that keeps oil and dust away from the leaf. Size on the coincident peak of rolling, drying and packing, commonly 3 to 8 cubic metres per minute for a mid-size factory, and keep the compressor intake away from leaf dust and firing heat. Tea is not coffee roasting: the loads are lighter, the air touches the leaf directly, and hygiene matters more than raw flow. QiAir, a Chinese screw compressor manufacturer and supplier, sizes machines for this food-adjacent duty.
Tea is handled gently, and its air should be too. Withering troughs use air for even airflow and control, rolling machines use it for pressure and handling, dryers and firing machines use it for damper and burner controls, and sorting and packing lines use it for separation, weighing and sealing. The leaf is the product, and it is exposed: oil or wet air at any of those points can taint flavour, spot the leaf or spoil a seal on a retail pack. QiAir is a Chinese manufacturer and supplier of screw air compressors, and its machines for tea factories are specified around clean, dry, food-safe air rather than maximum flow.
Tea processing is seasonal and batch-driven, which changes the sizing question. A factory that runs hard for eight weeks at harvest and quietly for the rest of the year needs a compressor that is efficient at part load, not just at full load. This guide maps the tea air users, explains how to size for harvest peaks without oversizing for the quiet months, covers leaf dust and hygiene, and sets out a sizing sheet for a China supplier.
Where Air Is Used: Withering, Rolling, Drying, Sorting and Packing
Withering is the first air user and the most delicate. Airflow through the trough must be even and controllable, and the valves and dampers that set it run on compressed air. Rolling follows: rolling machines use air for pressure control and for handling the leaf between stages, and a jerky supply changes the roll and therefore the liquor of the finished tea. These are low-flow, high-sensitivity users, and they reward a stable pressure far more than a large compressor.
Drying, sorting and packing add the volume. Dryers and firing machines use air for damper and burner controls, sorters use it for separation and cleaning, and packing lines use it for weighing, filling and sealing retail packs and bulk sacks. Packing peaks at the end of the day when the dried leaf is bagged, so the compressor sees its hardest hour when the dryers are still running, and that coincidence is what the sizing must cover.
- Withering and rolling: even airflow, damper control and rolling pressure where stability matters more than flow.
- Drying and firing: damper and burner controls that need dry air through every firing cycle.
- Sorting and packing: separation, weighing, filling and sealing where oil or moisture spoils the pack.
Sizing for Harvest Peaks Without Oversizing the Quiet Months
List the users that run together during a harvest shift, not the users that exist in the building. A mid-size tea factory typically peaks at 3 to 8 cubic metres per minute at 7 to 8 bar, which is roughly a 22 to 45 kW screw compressor, and a variable speed drive is almost always the right choice because the load swings between harvest and off-season by half or more. A fixed-speed machine that unloads for hours in the quiet months wastes power every day, while a variable speed machine follows the load and keeps pressure steady for the rolling machines.
Keep the pressure drop to the farthest packing line under 0.3 bar at peak, and fit a 300 to 500 litre receiver for a small factory or 500 to 1000 litres per 10 cubic metres per minute for a larger one. A ring main helps when withering, drying and packing sit in different buildings, and a pressure gauge at each area lets the factory find a fault in minutes. Verify pressure at the farthest packer during a harvest shift, not on a quiet day, because the quiet-day reading will always look fine.
- Size on the harvest-shift coincident peak, and choose a variable speed drive for the seasonal swing.
- Allow 500 to 1000 litres of receiver per 10 cubic metres per minute, and keep far-end drop under 0.3 bar.
- Verify pressure at the farthest packer during harvest, and log it weekly through the season.
Leaf Dust, Hygiene and Dry Air
Tea leaf dust is light, dry and everywhere during withering and sorting, and it clogs an intake filter faster than most factory dust. Put the compressor intake on the clean side of the building, away from withering troughs and sorting lines, and check the filter weekly during harvest, keeping a spare on the shelf. A choked intake raises discharge temperature and power draw, and in a food-adjacent plant it also raises the risk that dust finds its way into the air system.
Treatment is three stages in series: a pre-filter, a refrigerated dryer to a 3 degree C pressure dew point, and a coalescing filter to 0.01 micron, with an activated-carbon filter where the factory standard requires oil-free quality air. Use food-grade compressor oil where the machine uses it, and test the air at the packing line each season for oil and moisture. Slope lines to drain legs, fit automatic zero-loss drains, and keep the compressor room clean and ventilated, because a clean room is the cheapest hygiene measure a tea factory can buy.
- Keep the intake away from leaf dust, check the filter weekly during harvest and keep a spare.
- Fit pre-filter, refrigerated dryer and coalescing filter, with a carbon filter where oil-free air is specified.
- Use food-grade oil where applicable, test air at the packing line each season, and drain every low point.
Buying from China: Sizing Sheet for a Tea Factory Compressor
QiAir is a Chinese manufacturer and supplier of screw air compressors, and a tea-factory order should start with a seasonal load sheet. Send the supplier the harvest peak flow at 7 to 8 bar, the off-season flow, the number of withering, rolling and packing lines, ambient temperature and humidity, and the distance to the farthest packer. Ask for a variable-speed quotation with the part-load power curve at 50 and 75 percent load, because those are the loads the machine will actually run at for most of the year, and confirm the dryer duty and filter grades in writing.
Agree the acceptance test before shipment: a full-load run at rated pressure, a dew point reading at the dryer outlet, and an oil-aerosol check at the filter outlet. On arrival, install on a level plinth with clear cooler airflow, connect drains before the first run, and survey pressure at the farthest packer during the first harvest shift. Keep a log of pressure, dew point and filter changes through the season, and review it at the end of harvest, because that review is what sets the right service schedule for next year.
- Send the supplier harvest peak and off-season flow, line count, ambient conditions and farthest-packer distance.
- Ask for variable-speed pricing with power at 50 and 75 percent load, and confirm dryer and filter grades in writing.
- Accept on a full-load test plus dew point and oil checks, then survey pressure during the first harvest shift.
Frequently asked questions
What size screw compressor does a tea factory need?
A mid-size tea factory typically needs 3 to 8 cubic metres per minute at 7 to 8 bar, roughly a 22 to 45 kW screw compressor. Size on the harvest-shift coincident peak of rolling, drying and packing, and choose a variable speed drive because the load falls by half or more off-season.
Does tea processing need oil-free air?
The air touches the leaf and the pack, so it should be oil-free in quality even if the machine is oil-injected. Use a pre-filter, refrigerated dryer, 0.01 micron coalescing filter and carbon filter, or an oil-free compressor, and test the air at the packing line each season.
How is tea different from coffee roasting for compressed air?
Tea loads are lighter and steadier, the air touches the leaf directly through withering and rolling, and the season swings hard between harvest and quiet months. Coffee roasting is hotter and more batch-driven around the roaster, while tea rewards stable pressure, clean dry air and a variable speed drive for the seasonal swing.
Related reading
- How to Choose the Best Screw Air Compressor Manufacturer in China for Your Factory
- Two-Stage PM VFD Screw Compressors: How a Top China Supplier Cuts Factory Energy Costs
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.