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Need a quote for Ultra Silent Duct Fans? Send airflow, static pressure, voltage and quantity — an engineer replies within 1 business day.Send specs to an engineer →
Have your duty point?

See every LONGWELL model whose P-Q curve covers it — margins, noise and power included. No login.

Library: Ø25–1,000 mm, single units up to about 52,000 m³/h — larger duties go straight to an engineer. Prefer to talk it through? Send your specs to an engineer Browse all Ultra Silent Duct Fans models with curves on the Fan Selector →

Buying from LONGWELL

  • Brand owner since 1990
  • Yuyao, Ningbo
  • 12-month standard warranty, extendable to 18–24 months by project agreement
  • Reply within 1 business day

Certificates you can check

Product certificates cover only the models listed on each document — ask which ones apply to your model. ISO certificates cover management systems, not products. Declaration of Conformity for your model and destination on request.

All document scans and what each covers

Test & release at LONGWELL

Specified and drawn by LONGWELL, built to our drawings by qualified partner factories, inspected and released to LONGWELL standards.

  • Wind tunnel · AMCA 210 method
  • Semi-anechoic room · sound power testing
  • Outgoing sampling to AQL 2.5
  • Test records retained for 5 years

How ordering works

  1. Spec check duty point & drawings
  2. Samples 1–3 days (stock models), fee credited to first order
  3. Validation on your bench
  4. Order T/T 30/70 (first order)
  5. Production & release 15–30 days, partner factory
  6. Shipping & after-sales FOB · CIF · DDP
Full terms, QC and FAQ
Current book for Ultra Silent Duct Fans

Ultra Silent Duct Fans

– Material： Plastic / Metal – Customizable features include time delay, temperature sensors, humidity sensors, and other tailored functionalities. – Integrated backdraft damper to prevent the return of air and entry of insects. – Ensures stable performance with slow start-up, unaffected by voltage fluctuations. – Double diameter connection provides a sealed, leak-proof, and shockproof design. – In automatic mode, the controller adjusts the fan to high speed when air quality (temperature, humidity, VOC value) exceeds the set threshold, and the fan stops once the air quality drops below the set value. By drawing inspiration from industry leaders while maintaining a distinct brand voice, Longwell can effectively communicate the superior design and performance of its products to customers.