Overview
EN ISO 13351:2024 - Fans: Dimensions (ISO 13351:2024) is a CEN-endorsed international standard that defines dimensional requirements for circular and rectangular flanges of general‑purpose fans and the fan size designation system. It applies to industrial and commercial fans (light-, medium- and heavy‑duty) and is explicitly not applicable to cross‑flow fans or fan appliances for individual household-type applications. The standard promotes interchangeability and reduces technical barriers to trade by standardizing pitch diameters, bolt patterns and hole sizes while allowing design flexibility for flange thickness and external details.
Key topics and technical requirements
- Scope & applicability
- Covers circular and rectangular flanges and fan size designation for general‑purpose fans.
- Excludes cross‑flow fans and household fan appliances.
- Flange series
- Three circular flange series: light‑duty, medium‑duty, heavy‑duty (heavy series includes larger sizes for marine/heavy industry).
- Dimensional parameters specified
- Only pitch circle diameter, number of holes, and hole diameters are mandated to avoid over‑constraining design.
- Flange thickness, internal/external flange diameters and other details are free within good engineering practice.
- Design rules
- Nominal impeller tip diameters follow the Renard R20 series and preferred numbers (ISO 3 / ISO 497).
- Typical nominal sizes range from 100 mm to 2 000 mm, with heavy‑duty sizes up to 3 550 mm.
- Bolt hole counts are divisible by four and symmetrically disposed to allow 90° orientation and split‑casing arrangements.
- Duty definitions
- Light‑duty: non‑toxic, non‑corrosive air, up to 2 kPa (temperature limits specified).
- Medium‑duty: designed for pressures up to 10 kPa.
- Heavy‑duty: designed for pressures up to 40 kPa.
Practical applications and users
- Fan manufacturers: apply standard flange dimensions to ensure compatibility across product lines and with customer ductwork.
- HVAC and ventilation designers: use standard bolt patterns and size designations when specifying fans for buildings and industrial systems.
- Marine and heavy industry: rely on heavy‑duty flange series for robust fan installations.
- Procurement and installers: match fan flanges and ductwork for fast installation and reduced custom fabrication.
- Test labs and certification bodies: reference standard dimensions in conformity and interchangeability checks.
Related standards
EN ISO 13351:2024 is essential for anyone specifying, manufacturing, installing or procuring industrial fans who needs consistent, interoperable flange and size definitions across markets.