CFM loss

[unseenghost]

Okay after trying to find information I have come to one conclusion, or maybe two. I shouldn't search for answers in my condition although it is really fun. Two I am not sure if it was posted somewhere. Anyway here is my question.

I am setting up a new tent. I want to vent the can filter 33 to my max fan 6, but I got the wrong size flange it is a 4" one. I really want to know if using a 4" to 6" reducer in reverse has any affect on the CFM of the fan?

 

[pcduck]

Anytime you add a reducer it will effect for fans performance.

 

[unseenghost]

Going from 6 to 4 greatly effects the flow but is it the same going from 4 to 6? I am going from a 4 inch flange to a 6 inch exhaust fan and duct. Lets see if I can make this clear. Air gets pulled thru the carbon filter the 6 inch fan is pulling air thru. the filter has the 4 inch flange on it and a reducer inverted taking the 4 inch flange to the 6 inch fan. Really making it an inlarger not a reducer. now is the flow still being restricted?

 

[pcduck]

now is the flow still being restricted?

Yes, You can pull more air through a 6" hole then you can 4" hole

 

[ShOrTbUs]

the 6" fan is designed to pull air through a 6" opening, but reducing the airflow down to 4" when it gets to the filter will reduce the amount of air the fan can pull through the opening. the filter itself will cause drag by the fact that the air will be pulled through a semi permeable substance (activated carbon). which is what "cleans" the air. air is most efficiently moved when there is a high amount of velocity, and the least amount turbulence being created while moving the air.

some common causes of turbulence & reduced velocity are...

bends, turns, kinks, holes, long lengths of ducting, & restrictions (carbon filters, duct mufflers),

also reducing airflow will create more noise

now, if you are running a 1k hps you will need to upgrade to a 6" carbon filter. the reduction in cfm the reducer is creating will not be sufficient to properly cool a 1k hps alone. i run a reducer on my 435 cfm 6" fan with a 600w bulb and my room runs around 78F. if it was summer i would need additional cooling to keep my room running at the proper temps.

 

[The Hemp Goddess]

Keep in mind that a 4" hole is 1/2 the size of a 6" hole and I think that you will see that this cannot help but cause a restriction in the airflow.

Reducing airflow does not necessarily create more noise. My 6" Vortex runs quieter when I turn the speed controller down.

 

[ShOrTbUs]

Keep in mind that a 4" hole is 1/2 the size of a 6" hole and I think that you will see that this cannot help but cause a restriction in the airflow.

Reducing airflow does not necessarily create more noise. My 6" Vortex runs quieter when I turn the speed controller down.

Yes sry poor choice of words. Restriction was what I meant

 

[unseenghost]

Okay convinced to just order the right flange. It's on the way now Thanks for the help.