anyone understand air flow rate calculations?

[Dr House]

I have a manrose MF125 Fan
http://manrose.com/specifications/mixflorange.pdf

I need to vent this fan through the roof its quite a powerful fan, stats here:

I am looking for a terminal vent for the roof (Slate roof)
I wanted to install a Ubink UB41
http://www.ubbink.co.uk/connect/1684/_32_1072_1684_/C/Tile_and_Slate_Terminals/
Stats here for it: NB look at the 125mm

However I was worried that the pressure from the fan would be too high or it would not allow a high enough flow rate through the vent.

Does anyone know if I am on the right track? or can someone suggest another product?

 

[DavidMarq]

From the info above the 110 dia vent would be adequate, personally I would opt for a 150 dia vent as then the face velocity at 86 l/s would be less than 5 m/s. Good practice is to keep face velocity less than 5 m/s to avoid noise. I would also use 150 dia duct for the same reason.

 

[Dr House]

Thanks.

the thing is the outlet pipe on my fan is 125mm so I think I can only use the 125mm fitting on the ubink UB41

 

[alx]

Thanks.

the thing is the outlet pipe on my fan is 125mm so I think I can only use the 125mm fitting on the ubink UB41

If you pick 125mm, then if the fan goes over ~220m3/hr flowrate you're going to get velocities over 5m/s, and hence possibly noise.

Can you set the fan so it doesn't exceed this flowrate?

 

[Nightglow]

Thanks.

the thing is the outlet pipe on my fan is 125mm so I think I can only use the 125mm fitting on the ubink UB41

Did you not have a stepped adaptor with it, which you cut to the diameter you need for the ducting, anything from 100m up to about 150mm.

You cut to size & then glue it to spigot on the vent.