Indoor Carbon filter/airflow questions

[Keshmeng]

lets say you have a airproof box, and a fan inside out of the box, and then through a filter...

would this create negative pressure since your fanning air out... or will it increase pressure inside the box because your forcing air through because of resistance (carbon filter) and would this perhaps force air through air leaks (which is unwanted due to smell, so everything is preferably going through the filter)??

 

[Nelson]

I have never actually measured any pressure change with an exhaust fan going and no inlet fan going. But it does make a big difference in how much air blows out the exhaust fan with the inlet fan turned off. I can feel the change of the air flow with my hand. One of these days I will actually put in a bubble tube with the outlet air on one side and the room air on the other and try and measure the fdifference.

lets say you have a airproof box, and a fan inside out of the box, and then through a filter...

would this create negative pressure since your fanning air out... or will it increase pressure inside the box because your forcing air through because of resistance (carbon filter) and would this perhaps force air through air leaks (which is unwanted due to smell, so everything is preferably going through the filter)??

 

[TshirtNinja]

with your scenario, the fan would create negative pressure to the degree that it can pull vs the outside air pressure. technically no air exchange is going on and instead you are trying to create a vacuum. but since im pretty sure thats not what you meant then yes your area will retain negative pressure to the degree that the intake is overpowering the air intake.

 

[TshirtNinja]

yes it will. anything sucking harder than it is being brought in creates negative pressure even if it is slight.

 

[Nelson]

OK guys I'm taking down my barometer to the room. Not as sensitive as a bubble tube but it might read it. Should be easy enough to check.

Without an intake and with just exhaust the pressure will be lower in the box regardless of filter.It should be lower with no filter, although pushing through the filter slows the exhaust only.