c10's Flow Hood Build

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c10h12n2o
serial dilutor

Registered: 01/21/15
Posts: 3,200
Loc: the abyss

c10's Flow Hood Build

13
#24201748 - 03/29/17 04:30 AM (9 years, 4 months ago)

INTRO / BACKGROUND

hello lovely people, ive been getting lots of requests for a guide to how i built my flow hood so here it is :smile:

first of all, i memorized these pages, and would recommend doing the same for anyone building a flow hood/cabinet:

PirateSwazey's Flow Hood Build Thread

The Ubiquitous fungifun Flow Hood Guide

EvilMushroom666's Guide

Basically everything in here is the same as you will find in those guides, with only a few stylistic differences, those guys did a fantastic job and id have never built mine without those pages.

PLANNING

First, do you really need a flow hood/cabinet to do what you are trying to do? most hobbyists and even small commercial growers have no real need for laminar flow, since basically everything can be done in a SAB quite effectively. When used correctly, a still air box meets all the needs of most cultivators.

if you are having trouble getting the results you want with a SAB, there are a few things you can do that are easier than building a flow hood. #1 improve your clean tech and understanding of how a SAB works (still air vs sterile), #2 add a damp towel to the bottom of your SAB and elevate a cookie sheet a few inches above it with spacers, and use this as your work surface (this traps contams and can have a hu.ge impact on SAB success)

here are a few pics of my old SABs, a double hatch modified tub and a totally custom plexiglass closet build, the latter was extremely effective and comfortable to work in:

after deciding that a flow hood/cabinet is something you want, the next part is planning. I looked at dozens of real flow hoods in lab catalogs for inspiration, and finally settled on a design. I decided to go with a full flow hood rather than the standard flow cabinet that most people build on the forum, and had lots of features in mind. Here is the basic design decided on and began modeling:

here is a link to a rar file with the sketchup files and the exact cut dimensions:
FH Cuts and Model Files

Blower & Filter Matching Math

This part confuses a lot of people but it is a lot simpler than it might seem. We want a flow of around 100 feet per minute, so we need to:

#1 calculate the area of your HEPA filter. In my case, it is 2ft x 2ft = 4 sq. ft.

#2 multiply filter area by desired flow rate. in my case, 4 sq. ft. x 100 feet per minute = 400 cubic feet per minute

this number is the amount of air your blower must deliver at the sum of the STATIC PRESSURE of the HEPA filter + prefilter.

most HEPA filters of this type will be around 1" static pressure, and most prefilters will be around .2", which is the case with my filter from FP. so in my case, i need a blower that can do at least 400 CFM @ 1.2" static pressure

You can get great deals on used/salvaged blowers on craigslist or by calling HVAC repair shops and asking about salvage blowers, will save you several hundred dollars at least on the blower. the tricky part is finding something just right, and finding the blower info. for mine, i was looking for a 1/3 hp blower, but ended up getting a 1/4 and a 1/2 hp in the hope that one would work. you can always restrict the airflow or use a speed controller if it is too much

Since i couldnt find ANY info on the two salvaged blowers i found, i ended up getting one of those anemometers to determine cfm and flow stats, which indicated that the 1/4 hp was over 1200 CFM and would probably be sufficient. just in case, i designed it big enough for the 1/2 hp if i needed to switch them out

Construction

I made my cuts out of 2x 8' pieces of 3/4" plywood, and screwed the bottom and sides together, then put a sheet of metal onto the bottom and secured it with contact cement and countersunk screws

after that, i installed the furring strip and some cleats to hold the middle platform

then i put the filter (with all the protective wrap and cardboard intact) inside and lined everything up, just to make sure everything was snug and fit right. I placed the middle platform in and drew some of the lines to cut it off, and sat the blower in place to make sure everything looked right, then mounted the middle platform in place

after that i cut the windows and the blower hole

and put together the front and top (the prefilter mount):

then i caulked and painted everything in 2 coats of VOC free semi gloss enamel

took everything to its final location and pressed the filter into place, secured it with pegs into the filter housing, mounted the blower, screwed the front and top in place, caulked em, and painted em again, wired the blower and lights, put a AC socket, a USB quickcharger, and a router speed controller on it, and mounted plexiglass on the inside with countersunk screws, so that the interior workspace is perfectly smooth and easy to clean

So far so good, been really loving it!! perfect laminar flow all the way around :smile:

it has been a joy to work with. the pins into the filter housing are a totally different way of securing the filter than the standard trim-sandwich that most flow cabinets use, and i was a bit skeptical at first, but its worked out well :smile:

I really love the USB quickcharger built in, and the lights as well. I have a tracing pad (backlight) that i slide under the rack when i want a backlight to see through agar as well

huge thanks to RR, bodhi, anno, agar, workman, pirateswazey, EM666, and everyone else who helped me out when i was brainstorming on this thing, you guys rock!!! mush love my friends!!! :rockon:

--------------------

C10's Agar Guide + Tips and Tricks | c10's Flow Hood Build Guide

"Partial knowledge is more triumphant than complete knowledge; it takes things to be simpler than they are, and so makes its theory more popular and convincing."

"Convictions are more dangerous enemies of truth than lies"
― Friedrich Nietzsche

Edited by c10h12n2o (05/18/21 05:51 PM)

Extras:

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