DIDW Double Inlet Double Width Fans
High-flow, EX-certified centrifugal fans engineered for offshore, nuclear and hazardous area environments.
Highly-adaptable and Reliable Compliance
Our DIDW fans are designed and tested in line with ISO 15138:2018 offshore HVAC standards, giving you complete confidence in their suitability for the harshest marine environments. Built with corrosion-resistant materials and marine-grade finishes, they are fully equipped for offshore oil & gas platforms, FPSOs, and marine vessels. With integrated safety features for both Zone 1 and Zone 2 classified areas, every unit is engineered to deliver safe, reliable performance in explosive atmospheres.
Key Features of Our DIDW Fans
Our DIDW fans provide high flow and superior efficiency through a double-inlet, double-width design that moves large volumes of air at lower tip speeds for reduced energy consumption. The balanced dual-inlet arrangement minimises turbulence, delivering lower noise and vibration for quieter, more stable running. Despite their compact footprint, these fans are remarkably powerful — capable of delivering nearly double the output of an equivalent SISW fan. Construction is flexible to meet site needs: choose from backward lamina, backward curved or airfoil impellers and specify direct-drive or belt-drive arrangements, specialist impeller materials, and marine-grade finishes for harsh, corrosive environments.
Download our DIDW Fan Spec Sheet
A DIDW (Double Inlet Double Width) centrifugal fan uses two air inlets and a wider impeller to generate high-volume airflow at a given pressure rise. This design gives the airflow capacity of almost two single-inlet fans while running from one motor and occupying less space. The result is efficient, smooth airflow with lower tip speeds, reduced noise and improved mechanical balance — making DIDW fans suited to large-volume HVAC, process ventilation and hazardous-area extraction where space and safety matter.
We supply DIDW fans with full hazardous-area and offshore compliance. Certification options include ATEX to EN 14986 for hazardous atmospheres, IECEx compliance with IEC/ISO 80079-36 and 80079-37, and ISO 15138:2018 conformance for offshore HVAC fan requirements. Where projects demand classification society support, we provide documentation and testing to support ABS and DNV requirements. We also support UK-specific certification routes where required.
DIDW fans can be built in a range of materials to suit the operating environment, including carbon (mild) steel for general industrial use, stainless steel grades 304 and 316 for corrosive or hygienic conditions, and duplex stainless steel where extra resistance is required. Hot-dip galvanised constructions are available for outdoor and semi-aggressive sites. Standard surface protection is zinc phosphate; optional coatings include epoxy, bead-blasted stainless and C5M high-build marine finishes for offshore service.
We provide a complete lifecycle service for DIDW fans: site surveys and application engineering, bespoke design and manufacture, factory acceptance testing, installation supervision and commissioning, scheduled maintenance, on-site repairs, balancing and vibration analysis, spares supply and retrofit upgrades. Our team can also deliver FAT documentation, full traceability and certification packs for safety-critical installations.
Bespoke Designs - Engineered for Your Application
Every application is different – and so are your requirements. That’s why Woodcock & Wilson offers fully bespoke DIDW fan solutions, tailored to suit your exact specifications.
Whether you need a unique mounting arrangement, specific airflow characteristics, specialist coatings, or integration with existing control systems, our in-house engineering team will work closely with you from concept to commissioning.
We regularly deliver:
- Custom-built casings and mounting plates
- Specialised materials for corrosive or hygienic environments
- vibration control options
- Adaptations for restricted or unusual space requirements
