More than 800 centrifugal fans are to be supplied for the Riyadh Metro ventilation system, engineered to meet the EN 12101-3 smoke exhaust requirement for life-safety performance in underground stations. The order covers both daily ventilation and emergency smoke control in one package.
Ventilation Needs of a Metro Station
An underground station is a confined space with trains, passengers, and fixed plant, so it needs two ventilation regimes. In normal service, fans exchange air to keep temperature, humidity, and air quality within limits for commuters and staff. In a fire, the same or dedicated fans must extract smoke along defined paths so escape routes and the platform stay tenable while people leave, because a stalled tunnel fills with smoke faster than most imagine.
The EN 12101-3 standard sets the test for powered smoke and heat exhaust ventilators, proving the fan can operate at high temperature for a defined period. For a metro, this means the selected centrifugal fans must hold their duty at elevated temperature, not just at ambient, which drives the motor location, balancing, and housing specification. A fan rated only for comfort air is useless the moment the strategy needs it most.
Centrifugal fans suit this duty because the station ductwork and shafts carry real resistance, and the fan must hold a stable pressure as the system changes between normal and emergency modes. The 4-72 and 4-79 series are typical choices where the duty is mostly ventilation with occasional high-temperature demand, because their curve stays stable across the swing.
The control layer is as important as the fan: the ventilation must shift mode on fire alarm, proving the fans start, run, and report. A metro cannot rely on an operator flipping a switch during an evacuation, so the interface is part of the specification, not an afterthought.
Fan Package Parameters
The table lists the key figures for a metro-scale ventilation package, the scale that tests both product and production discipline.
| Item | Specification | Note |
|---|---|---|
| Quantity | 800+ fans | station ventilation |
| Type | centrifugal, 4-72 / 4-79 | high-resistance ducts |
| Standard | EN 12101-3 | smoke exhaust rating |
| Airflow | up to 60,000 m3/h | per large unit |
| Pressure | up to 1,500 Pa | shaft and duct loss |
Supplying 800-plus units also means disciplined production and testing, because a metro programme cannot absorb inconsistent performance across stations. Each fan is verified against its duty before it leaves the factory, and the batch is documented so any unit can be traced to its test.
The pressure figure reflects not just the fan but the shaft and duct design, so the station engineer and the fan supplier must agree the resistance rather than guess it, or the fan arrives unable to meet the smoke extract rate.
Selection Checklist for Transit Ventilation
Engineers on transit projects should confirm these points early, because a metro is unforgiving of a fan that misses its duty.
- Separate the regimes: define normal ventilation and smoke extract duties, then confirm one fan serves both or plan dedicated units.
- Prove the rating: require EN 12101-3 evidence, not a catalogue claim, for smoke fans.
- Match the curve: size to real shaft and duct resistance, including the fire case.
- Plan maintenance access: 800 units need a service plan and spare impellers.
- Verify at source: factory performance testing reduces on-site surprises.
Significance of the Project
A metro ventilation order of this scale is a test of both product and production discipline. The fans must perform identically across dozens of stations and keep performing through a 30-year asset life, which is why verified testing and a documented quality system sit behind the supply rather than a hope.
For the region, reliable underground ventilation supports safer, higher-capacity public transport as cities expand, and a consistent fan package is what lets the operator maintain one spare-parts list across the network instead of dozens.
The order also shows that a single supplier can cover a transit programme's whole ventilation scope, which simplifies the operator's life more than the headline count suggests.
An aspect easy to overlook in a metro package is acoustic isolation, because a large fan in a confined station can transmit vibration into the structure and annoy passengers or staff even when the air is right. The fan should be specified with flexible connections and isolated mounts, and the duct near it lined or silenced, so the rating that protects lungs does not trade off against a noise complaint. The station engineer should see the noise figure as part of the duty, not a separate document, and the supplier should be able to state the outlet sound level at the duty point. A ventilation system that meets the smoke extract rate but hums through the platform is a partial success, and the metro operator lives with both the air and the sound every day.
Keruite engineers respond to selection enquiries within 24 hours, backed by the factory's own performance testing laboratory and more than 30 years of fan manufacturing experience.