Fan Question

Hey guys, looking for some advice on cpu fans and the transformers they are being wired to. I've got two fans, both the same, 75 cfm and say DC 12V 0.25 A. Then I have two transformers, the first one ( well call A) says Input: av 120v 60Hz 5w output: DC 6v 300mA. And the second (well call it B) is input: 12V 60Hz output: 9v 500mA. The fan wired to "B" blows a lot more air than the fan wired to "A". Which makes sense seeing at "B" has 3 more V and 200 more mA. So my question is : Am I getting all the power possible out of fan "B"( am I really getting a full 75cfm with this transformer). If not what would the ideal numbers be? And is the 0.25 A the same thing as 250mA? I'm going to be using these fans for my carbon scrubber so I need them to work to their full capacity. Any advice is appreciated

Hello! For getting all the power of fan you may be use 12V power supply unit (not less than 0.5 A if fans being wired parallel). In you case none of fans wired to A or B transformer don't take 75 cfm.
Yes, the 0.25 A is the same thing as 250mA.
Note. CPU fans is the axial fans with low air pressure and its a poorly suited for scrubber.
Sorry for my bad English.

Right on, thanks for the information! What kind of fan would you recommend for a Carbon Scrubber?

Duct fans is recommended to use with carbon filter. This type of fan specially designed to be built in ventilation duct and reach more pressure than CPU fan.
For example http://www.amazon.co.uk/TT-Mixed-Flow-Extractor-Fan/dp/B003DKA7LG/ref=sr_1_23?s=kitchen&ie=UTF8&qid=1378043484&sr=1-23
But if the box size is small it will be a problem

Yeah it's 2x2 and 3 feet tall, not sure where I could fit a fan like that....

But 2x2x3 feet is normal dimension of box for fit fan like on link. My box have slightly lower size (53x43x85 cm) and I used comparable size fan. Unfortunately, it stole useful area inside box, but fit is possible.