Farm Ventilators: Air at Working Pressure, Not the Free-Air Number
- An energy-efficient farm ventilator is the fan that still moves the air the house needs once pads, cages and shutters are in the way.
- Big Dutchman publishes cone fans for tunnel houses where counterpressure is high. Big Herdsman is the other name buyers already compare on 50-inch class negative-pressure fans.
- Weifang Splendid supplies fiberglass and galvanized exhaust fans, with pads. Count fans from house size and bird weight, not from a brand list.
The free-air figure on a fan plate is the open-wall number. A poultry house is not an open wall. Pads, inlets and a full cage row add resistance. The fan that looks larger at 0 Pa can fall behind once the house is closed up. That is the check, before motor watts.
What the two catalogues actually show
Big Dutchman describes its AirMaster cone fans as the choice when barn equipment raises counterpressure, and states pressure resistance up to 100 Pa on the AirMaster 140, with IE3 motors on that frame. Cone on the outlet is there to hold airflow as pressure rises, not as a decoration. Big Herdsman is compared in the same conversations on the 1380 mm negative-pressure fan: third-party listings put that class around 44,000–48,000 m³/h at 1.1–1.5 kW. Those are catalogue classes, not a house result. A house result is airflow at the pressure the pads and the row actually make.
| Check | Why it decides the fan |
|---|---|
| Air at working pressure | 0 Pa is an open wall. Pads and cages are not. |
| Cone or box | Cone holds flow when the house pushes back. Box is the simpler shell. |
| Shutter | Has to close when the fan is off, or the house leaks in cold weather. |
| Shell | Fiberglass on the wet pad end. Galvanized where the air is drier. |
| Pad match | Fan count without pad area only moves hot air. |
How the count is cut
Summer air is sized to pull heat. Minimum air in the brooding week is a smaller set of the same fans, on a cycle, with inlets still open. Weifang Splendid marks fan count after house length, width, eave, bird numbers and target weight, and whether the row is floor or cage. No saving percentage is printed here. A fan that cannot hold flow against the pad is not the efficient one, whatever the motor label says.
What to send
House length, width, eave, bird numbers, target weight, climate, and floor or cage. Say if a cone is required on the gable. That cuts fiberglass or galvanized fans and the pad wall.
FAQ
What makes a farm ventilator efficient?
Airflow at the pressure the house actually runs, not the open-wall number on the plate.
Cone or box fan?
Cone when pads and equipment raise pressure. Box where the shell only has to resist the house air.
Do fans replace the pad?
No. Fan count without pad area moves hot air.
What should I send?
House sizes, bird numbers, target weight, climate, floor or cage.
Send the house, not a brand shortlist.
Length, width, eave, birds, climate, floor or cage.