Circular Inline Fan
External-rotor inline duct fan with backward-curved impeller and overheat-protected motor.
About the Circular Inline Fan
A circular inline (mixed-flow) fan combines the airflow profile of an axial fan with the pressure capability of a centrifugal — all packed into a tube the same diameter as the duct it sits in. The motor lives inside the impeller hub (external-rotor design), so the fan is barely longer than a duct coupling and can be dropped into any straight run. Best suited to small-to-medium supply and exhaust loops where a full cabinet fan would be overkill.
Engineering Advantages
Same diameter as the duct — fits into any straight run with no transitions
Motor overheat protection with auto-restart — survives blocked-inlet faults
External-rotor design = fewer bearings and lower noise floor
Easy retrofit to existing duct systems
Key Features
- Dynamically balanced backward-curved impeller
- Direct-drive external rotor motor with ball bearing
- Motor with overheat protection and auto-restart
- Mounting brackets supplied as standard
- Optional pre-fitted hum-free speed controller
Construction & Materials
- Galvanised steel body with bolted service flanges
- Backward-curved impeller, dynamically balanced for low vibration
- External-rotor motor with sealed ball bearings — IP 44 standard
- Built-in thermal contact for over-temperature shutdown
- Mounting brackets and rubber isolators included
How to Choose the Right Variant
- 1Best for small-to-medium loops up to ~1,800 CMH / 1,100 CFM
- 2Pick duct diameter first; the fan slots straight into that size
- 3Add the optional speed controller if duty is intermittent or noise-sensitive
Installation Notes
- Hang from threaded rod with the supplied rubber isolators — never rigid-mount
- Maintain 1× diameter of straight duct upstream for stable flow
- Wire through a service-isolator switch within sight of the fan
Maintenance Schedule
- Wipe the impeller and hub once a year — dust accumulates on the hub face
- No bearing lubrication required — sealed for life
Industries Served
Standards & Compliance
- IP 44 motor protection per IEC 60529
- Performance tested in line with ISO 5801 chamber method
Frequently Asked Questions
How is this different from a tube axial fan?
A tube axial uses a straight axial impeller and produces lower static pressure. A circular inline uses a backward-curved (mixed-flow) impeller and can develop two to three times the static pressure for the same diameter.
Does the speed controller introduce hum?
No — we use solid-state hum-free speed controllers tuned for external-rotor motors. Stepless from ~30% to 100%.
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Need help selecting the right fan?
Our engineers will help you size the circular inline fan to your exact application — capacity, static pressure, and installation constraints.
