fans...its whats for dinner

[Green Goblin]

k..so this is a gas manometer:

http://www.growkind.com/gardens/greengoblin/1317/DSCF1556.JPG

it measures pressure or vacuum in inches of water guage, or "wg. inches of water is a very small unit of measure. to give you an idea 7"wg is equal to 1/4 of a pound per square inch guage, or psig. thats from zero to the lil line between the 6 and the 8 ;).

now this manometer reads from 0-1"wg. very small pressures. i can read the changes in atmospheric presure on this from day to day or morning to evening even...pretty damn cool.
its so far off cause it was laying flat, to get accurate pressure readings from any guage it must be held vertical, unless otherwise noted by the manufacturer...or if ur reading psi, then who gives a shit, buit here we're working with nanobearings in comparison, so...

http://www.growkind.com/gardens/greengoblin/1317/DSCF1553.JPG

now we zero the needle:

http://www.growkind.com/gardens/greengoblin/1317/DSCF1557.JPG

now there is a low and and a high connection on here. not needed for a guage with a positive and negative side, however as in the previous pic of the 0-10" guage, hooking the wrong hose up could slam the needle backward and bend the parts inside the guage.

http://www.growkind.com/gardens/greengoblin/1317/DSCF1559.JPG

the hoses must be hooked up as close to the fan as possible...every foot of ducting changes the pressure, whether its smooth or not. and due to my current state of mind i forgot to rotate this.

deal with it.

http://www.growkind.com/gardens/greengoblin/1317/DSCF1560.JPG

and if i had rotated that to the correct orientation, the guage below would have read positive.

:roll:

http://www.growkind.com/gardens/greengoblin/1317/DSCF1562.JPG

so now we know that the airflow restrictions in my box are causing .8"wg of pressure in my duct system. this includes the pipe, fittings, bulb, socket, the turn around the outer and inner tubes, my fart, oops...

for those of you not familiar this is my cool tube:

http://www.growkind.com/gardens/greengoblin/1317/0dualcooltube


anywho back on subject...

now open this link and make the window small so u can see it and this text easily.

http://fantech.net/fr2.htm

my fan most resembles the FR-110

so that first graph relates to the graphic representations of the fan below it. on the top we see that dimensions A1 and A2 determine duct sizes we can use...do not use duct smaller than this measurement, if you wanna use smaller duct buy a smaller fan. it wont move the same amount of air, listen or not, dont do it.

as we see here i would've been better off buying the fantech fan i could've used 5" duct...shizzle...anywho so we know we should use 5" if possible(less static pressure) but we can also use 4" if materials arent available. the other measurements are there to make sure u dont buy a fan that doesnt fit in ur box...

in the air performance charts below all that, we see the FR-110 is the queer purple line on the upper graph. we see also that at .8"wg my fan only moves 80-90 cfm. that means that setup only moves 90 cfm of air...period, no ifs ands or butts about it.

so some diots might say...

"wow if i put 2 cool tubes on the fan, that will double the amount of air available, wich means i could move twice as much air!"

wrong :dunce:

if you put 2 tubes on the same fan you would only be changing half of the system, so more than likely static pressure would drop but not dramatically. aside from that, say it did cut static pressure in half, for retarded conversation sake...

at .4"wg on the graph we move roughly 130cfm...so now we have 65 cfm through each tube...

gonna work? maybe...


gonna work as well?

FUGG NO!

:pimp:

anywho, Happy Growin' Peeps :pimp:

[Tiberon]

Excellent info GG.
Although....pardon my asking....Im curious how this effects the grow.(yes i read the WHOLE post)
Is that simply just there to tell you that your fan is only pullin 90cfm rather than what it was designed for? How does this affect you ventilation and what changes are you gonna make?
School me!

[Green Goblin]

im not making any changes...although my fan is not working to the best of its abilities due to the flaws in my setup...

my box runs 2 degrees above room temp...why fix it? :roll:

this was more of an explanation of the correct way to read the info on fan websites...too many times peeps dont understand that you cant estimate airflow restriction, it has to be measured....and if the fans website says it can move X amount of air is only true under certain circumstances. most grow ops dont have "ideal" circumstances. and this needs to be taken into consideration. i realise that peeps dont have access to this equipment, assumptions are necessary, but hopefully this will make the assumptions closer to the eventual outcome. ass you can see, my assumptions were off a bit...but i can sure as heckles tell ya that i'll be much closer next time ;)

Happy Growin' :pimp:

[Max Rockatansky]

"my box runs 2 degrees above room temp...why fix it? "

Dang that's sweet there GG I am running 10 degrees above room temp with a Pryrex cool tube.

Good job man I understand most of that, Are those gauges anything like a manometer for carbs?

http://users.pandora.be/eforum/emoticons4u/happy/317.gif

M R

[Green Goblin]

a manometer is a manometer

whether its used for carburetors or measuring the pressure created by exiting methane emmitions from an elephants ass.

u'll want one that reads from 0-1.5"wg prolly, depending on ur setup. theres a cheap good one available at johnstone supply, or possibly at any HVAC-R supply house. dont go to home depot, ace hardware maybe. dunno, grainger proly has em..or ebay even...anywho laterz

:pimp:

[marymaryquitecntrary]

thanks for the info, GG! i need to get one of those for my elephant. :D

[Green Goblin]

iguess it might be a good idea to add how to go about fixing this problem eh?


well for starters you need to identify where the restrictions in ur system are. mine is oviousely the cool tube. other than that i have 1 - 90, 1 - 45 and a foot and a half of pipe.

90's count as 15 feet of pipe and 45's count as 12 feet...to give you an idea of restrictive values for fittings.

so i would definitely need to reduce the restricion in my cool tube. to do this i'd need to either make the device more aerodynamic all together, or increase the most choked part of the system. in ur mind picture taking a slice out of that cool tube in any one spot. then pull it out like a transparency, and look at how little spacxe the air has to flow through... so i'd increase the size of the inner and outer tubes, allowing for more space between the bulb surface and the inner tube and between the inner tube and the outer tube.

if my exhaust fan pulled through the tube and out the box i would need to look at wherever the air is coming into the box, and see if there was any way to free that up at all...if ur fan speed increases when u shut ur doors, cut a bigger intake.

Happy Growin' :pimp:

[nobogart]

if ur fan speed increases when u shut ur doors, cut a bigger intake.

Happy Growin' :pimp:

what if your fan speed increases when you open the doors?

[Green Goblin]

k ur gonna have to describe ur setup to me