Wolter · 3 series
Tube fans for round ducts
Fans for round ducts — from compact models for false ceilings to size 500. They fit straight into the duct and are fixed with clamps.
An inline (tube) fan is installed in the duct between two sections and fixed with clamps. It provides local extract or supply without a separate plant room.
The Wolter range:
- RK / RS / ERM / DRM — backward-curved impeller on an external-rotor motor; plastic (RK) or steel (RS, ERM, DRM) casing, sizes 100–500;
- RF — compact centrifugal fan with circular spigots for false ceilings, 100–150;
- RFE / RFG — mixed-flow fans in a polypropylene casing; RFG with an EC motor, 100–150;
- SDB — sound-insulated box with straight or 90° airflow, 125–400.
Series
Inline tube fan series
RS / RK / ERM / DRM — inline tube fans
Round-duct fans with a backward-curved impeller: plastic RK and steel RS 100–355, ERM/DRM 315–500.
RF / RFE / RFG — compact inline fans
Compact fans 100–150 for false ceilings: centrifugal RF, mixed-flow RFE (AC) and RFG (EC) in a PP casing.
SDB — sound-insulated boxes for round ducts
Sound-insulated box with a forward-curved impeller for round ducts 125–400: straight airflow or a 90° turn.
Series comparison
| Series | Type | Airflow, m³/h | Pressure, Pa | Temperature rating |
|---|---|---|---|---|
| RS / RK / ERM / DRM | inline tube fan, backward-curved impeller | — | — | — |
| RF / RFE / RFG | compact fan for false ceilings | — | — | — |
| SDB | sound-insulated box for round ducts | — | — | — |
Choosing a series
| Task | Series |
|---|---|
| Small airflow, false ceiling | RF, RFE/RFG |
| Electronically commutated (EC) motor | RFG |
| Extract or supply through a round duct | RK (plastic) or RS (steel) |
| Larger sizes 315–500 | ERM (1 |
| Low noise | SDB |
Accessories
For installation and system build-up the manufacturer offers RSV clamps, RVK backdraft dampers, round-duct silencers and the TFB filter box. Step switches or speed controllers are matched to fans with stepped motors.
For rectangular ducts, see EKN/DKN and EK/DK duct fans.
Applications
Where they are used
FAQ
Frequently asked questions
What is the difference between RK and RS?
The casing material: RK is flame-retardant light-grey plastic with an integrated terminal box and guide vane; RS is powder-coated steel. Both have a backward-curved impeller on an external-rotor motor.
Which fan is best for quiet operation?
The SDB boxes: aluminium profile frame and galvanised panels with mineral wool, straight or 90° airflow.
Can a fan be installed above a false ceiling?
Yes, the compact RF and RFE/RFG in sizes 100–150 are designed for that.
Need equipment selection or a system design?
Send us the layouts or the brief — we will prepare a selection, a calculation and a quotation.