Can-Fan RK 125L Inline Fan 350 m³/h

Plastic duct fan with a 125 mm flange and 350 m³/h free air, from the same 70 W motor as the 100 mm version.

The RK 125L gets 80 m³/h more than the 100L out of an identical motor. That difference does not come from the fan. It comes from the duct.

The duct decides what you can pull

A 125 mm duct has over fifty percent more cross-section than a 100 mm one. The same volume of air therefore travels through it more slowly, and resistance climbs steeply with speed: roughly with the square of it. Moving from 100 to 125 mm wins you two things at once.

First, delivery. The same motor gives more because it is fighting less. Second, noise. Most of what you hear from an extraction system is not the motor but air rushing past bends, collars and filter caps. Slow the air down and that falls away.

In practice: if you are still free to choose your ducting, 125 mm is almost always a better start than 100 mm. If you are already committed to an existing 100 mm penetration, this fan has little to add there, because the flanges will not meet without a reducer and the reducer gives the gain straight back.

Why the impeller curves backward

The blades of a centrifugal impeller can curve forward or backward, against the direction of rotation. On the RK they curve backward. Such an impeller delivers slightly less air at zero resistance but holds its output far better once resistance is present. That is exactly the situation this fan works in, because there is nearly always a carbon filter in front of it.

A second property comes with it: a backward-curved impeller will not overload the motor if the resistance suddenly disappears, for instance when a length of ducting works loose.

Technical Specifications:

• Flange size: 125 mm
• Free air delivery: 350 m³/h
• Airflow at 100 Pa back pressure: 245 m³/h
• Power draw: 70 W
• Current: 0.3 A
• Weight: 2.3 kg
• Speed control: allowed
• Material: PA6 plastic
• Matching filter per Can: Inline 300

Frequently asked questions

Why does it cost about the same as the smaller 100L?
Because it has the same motor in it. You are paying for the motor block, not for the size of the flange.

Which filter does Can recommend?
The Inline 300. It is the only one Can names for this model.

Can I fit it to 100 mm ducting with a reducer?
You can, but it is a waste. The restriction costs you precisely the delivery you chose this model for.

Is 350 m³/h enough for a 100 x 100 cm tent?
Yes, with room to spare for a filter and a few bends of ducting.