EvilMushroom666's Flowhood Build

Discussion in 'MYCO-TEKS' started by EvilMushroom666, Jun 2, 2011.

  1. EvilMushroom666

    EvilMushroom666 Well-Known Member Moderator Mushroom Doctor

    May 27, 2011
    Here is my write up for the construction of my flow hood.

    After spending a year working inside of a glove box I had enough.
    I found the more I learned about agar and culture storage the more time
    I spent inside of my GB. After working in your GB for hours at a time
    your back starts to hurt, your arms start to hurt, and your time starts
    to dwindle as you are constantly loading and unloading your glove box.

    I came to the conclusion that an investment of $200-400 CDN to a
    laminar flow hood was money well spent. After realizing I could not
    afford to order a pre-built hood I choose to build my own. Here are
    the thought processes, obstacles, trials and tribulations I have
    encountered with building a hood from within Canada.

    I had a lot of help from many different members of the Shroomery,
    so many to list that I will not name drop here and just say a big
    thank you to everyone who has given me input.

    Material List:

    Buying brand new materials for this project would have avoided a lot of
    the troubleshooting problems I had. I learned a lot along the way and
    saved myself $400-500 for a blower to power my filter, but I paid for
    it with my time in troubleshooting,fixing, and rigging the salvaged
    furnace blower. Also if my blower ever dies on me it is not under warranty,
    were as most new blowers are warrantied for 5-10 years. Something to
    keep in mind.

    *Material I already had

    24"X24"X6" HEPA Filter Rated 99.99% @ .03 Micron - $218 CDN

    Large Squirrel Cage Blower - $30 CDN

    Wood - $40 CDN
    -4`X8` sheet of 3/4 " thick Douglas Fir Plywood (Sanded 1 Side)
    -1"X1" Furring Strip*

    Other Construction Supplies -$20
    -Carpenters Glue*
    -Screws (I used 1 1/4 Inch wood screws)
    -Drill bit set*
    -Good drill*

    Prefilter - $9 CDN

    TOTAL $317 CDN

    --------------------Do The Math--------------------

    You first need to figure out what size filter you are going to use, and
    then what specs you need for your blower.

    1. Find out the area of your filter by multiplying the width and the height in feet.

    I chose to use a 2ftX2ft HEPA

    2ft X 2ft = 4ft squared

    2. Multiply the required air speed(100 ft/min) with the area of your filter

    100ft/minX 4ft squared = 400 ft cubed/min

    So 400 ft3/min("cubic feet per minute") is the amount of air your
    blower must deliver at the sum of the STATIC PRESSURE of the HEPA
    filter + prefilter.

    RogerRabbit Note:
    "In a perfect world, a 400 cfm motor would supply that much.
    However, blowers are not 100% efficient, and then there's the
    friction in the plenum, turbulence, etc. I usually add ten to twenty
    percent to that figure."-RR

    So in actuality I will need around a 450CFM Blower rated @ 1" W.C to
    achieve laminar flow from a 2ftX2ft HEPA.

    --------------------Finding Your Filter--------------------

    I searched for HEPA's and found a lot of good companies in the states
    offering exactly what I needed. A 24"X24"X6" HEPA %99.99 @.03 micron
    filter. Problem was is most cases the shipping(Minus duties and taxes)
    cost more then the bloody filter! Using the list for HEPA sources on
    Fungi Fun I found a Canadian supplier that treated me well, found me
    exactly what I needed, and even made special shipping arrangements to
    spare me any shipping costs. Get on the phones people! Call around and
    talk to as many companies as possible and get quotes to find the best

    I had the option of a 6" Deep Filter, or a 12" Deep filter and I was
    not sure which would be better for my intended application...RR to the

    Specs of two HEPA's to choose from:

    Tri-Pure HEPA
    Standard Cap model

    Recommended Airflow = 250FPM(1.25 m/sec)
    12" deep @ 250 FPM = 1" W.G (250 Pascals)
    6" deep @ 125 FPM = 1" W.G (250 Pascals)

    A=24"X24" = 576 Square inches
    576/144= 4 square feet

    4 square feet X 250FPM = 1000 CFM 12" deep filter
    4 square feet X 125FPM = 500 CFM 6" deep filter

    RR Note:
    Some of the newer HEPA filters flow higher than we want at 1" of
    static pressure. In these cases, you need to run at a lower static
    pressure, because you really don't want more than 100 feet per minute
    leaving your hood.

    Based on the specs above, I'd go with the 6" deep filter because it
    has higher resistance. The resistance is what helps achieve laminar
    flow by creating pressure on the back side of the filter. If every
    inch of the back side is under pressure, the air flows smoothly out
    the front side.

    I'd go with the 6" filter and a blower rated at 450 cfm @ 1" W.G.

    If you are worried about them asking you what you are doing with this
    filter simply say that you are trying to propagate orchids using a
    a gel growth medium. Read up so you will be able to talk the talk.
    This avoids the ENTIRE stigma of mushrooms and if you talk the
    talk they will think nothing of it.

    Orchid Information Links

    I secured my filter for the price of $218 dollars Canadian after tax.
    From what I understand that is not a bad price at all for the filter.
    24"X24"X6" HEPA Filter Rated 99.99% @ .03 Micron
    PA190042.jpg View attachment 569

    NOTE: Make sure you get some weather stripping for your filter if it
    does not have a gasket. This will be pushed up against the furring strip
    to assure the air is blown through the filter and not around it.

    --------------------Finding A Blower--------------------

    810940025-PA240051.jpg moto1.jpg

    moto2.jpg moto3.jpg

    To save money I went with using a second hand furnace blower to power
    my hood. I searched online classified adds till I found a furnace
    blower for sale for $30. I went, inspected it, saw it run and purchased
    it right away. You could also try calling around and asking furnace
    places if they have any old unused blower motors with a similar
    rating to the one I found. Most places if you go about it the right
    way will give you a blower for free or next to nothing. If they ask
    what it is for say you need to ventilate your garage during the

    Here is the first major bump I ran into. I brought the blower home and
    set it up in the garage to play with it before I disassembled and cleaned

    EvilMushroom66 said:
    "If its not one thing its another. Went and took some pictures of the
    blower today, get an idea of its size and what exactly it is. I then
    plugged it in and let it run for a minute. At this time I heard a
    relay inside the motor click and it shut off. On closer inspection
    of the motor it is "Thermally protected". At this time the motor
    feels very warm to the touch, after only running for 1-2 minutes."EM

    The motor was not what I needed for this application...or so I thought.
    After a lot of troubleshooting and help from many board members in my
    post in Advanced Mycology this is what I found:

    EvilMushroom666 Said:
    Got playing around a bit today and have realized a few things:
    -The motor was kicking off without a belt yesterday AFTER having
    been run a few times and clicking off with the belt on.
    Today when I ran the motor without the belt it was fine and went on
    to run for 10+minutes without warming up at all. Upon reattaching the
    belt it would kick off after 1-2 minutes and output a LOT of heat.

    This is the 1/3 HP motor. Just to reconfirm that it was in fact the
    blower that is over working the motor I hooked up a spare 1/4 HP motor
    to the blower and it kicked the thermal protection after running for
    25 seconds. This same 1/4 HP motor would run FINE for hours on the
    makeshift grinding wheel it came off.

    This leads me now to a possible list of problems I need to fix:
    -I am thinking of dis assembling, cleaning and oiling the blowers
    -Look for a 1/2-1HP motor, would this be to much power to input into
    the blower tho?

    Either way it appears the motor is functioning fine, the mechanics of
    the blower leave a little more to be desired tho. Back to the drawing

    RR of the Shroomery found the problem

    RR Note:
    "That makes sense. In fact, your motor may be fine. It seems
    counter-intuitive, but there will be less load on the motor when it's
    installed and producing static pressure than there is now in free
    air. The reason is because less air will be moved, thus less total
    work is being done. The load of the air(static pressure) doesn't
    translate into increased load on the motor.

    As an experiment, try blocking part of the intake with cardboard, and
    then put a brick or something to block most of the output air from
    flowing. See if the motor runs without overheating.
    RR "

    Next I dis assembled everything and gave it a good clean

    clean4.jpg clean 3.jpg
    clean1.jpg clean2.jpg

    After the cleaning!

    clean 5.jpg

  2. EvilMushroom666

    EvilMushroom666 Well-Known Member Moderator Mushroom Doctor

    May 27, 2011

    I used these drawings for my plans, but changed the values for my
    filter size*Note* the strip inside of the box is the "Furring Strip"
    and is used to butt the weatherstripping on the backside of your filter
    upto in order to assure you have an airtight seal.

    [​IMG] [​IMG] [​IMG]

    Instead of having the two side pieces butt up against the top and bottom
    sheet like in the drawings, I made it so the sides rested on the bottom and held up the top piece. I did this for added stability.

    I do not have my drawings or measurements around but MAKE SURE YOU PLAN
    this step out. I went into my building center with all my measurements
    after planning my build and doing my drawings. I got them to cut my
    4ftX4ft plywood board into the 5 pieces I needed. I had some board
    left over that went to other projects.

    I am by no means a master carpenter so I kind of winged it and it turned
    out just fine. Here are some key points to remember in building tho:
    -Measure twice, cut once
    -USE WOOD SCREWS not drywall screws
    -Pre-drill all screw holes to avoid cracking your plywood
    -After you pre drill your holes lay down some carpenters glue before
    screwing everything together.


    -Install your furring strip and then silicone every seam as well as
    along the backside of the furring strip(To assure that the air is not
    forced around your HEPA instead of through it)


    Now worry about attaching your blower to your top

    -I used two pieces of 1"X2" to secure the mounting bracket down to the
    top board so the blowers output would be directed into the box. I then
    laid down a good amount of silicone on ever crack, crook and cranny to
    make sure it was sealed. After it dried I added another layer of silicone
    to be sure. I laid down silicone along the inside were the blower and
    plywood met as well. MAKE SURE ITS AIRTIGHT.

    build4.jpg build5.jpg build6.jpg

    -You then want to attache the top to your main box, glue, screw and
    silicone the shit out of all seams, cracks, crevices, as well as along
    the backside of the furring strip.

    -Vacuum out your box before installing your HEPA. Push it back into
    the hole and make sure the weatherstripping is tight against the
    furring strip. I then laid silicone down around any cracks or crevices
    around the entire filter smoothing it over the plywood and filter connection.

    -Attach your trim and silicone were the filter and trim meet

    --------------------Dialing In your Blower--------------------

    Now that I had everything assembled I needed to dial in my blower so it
    was near that wonderful sweet spot so my filter would bend a lighter
    flame 90 degree's. I started off by using cardboard and duct tape to
    seal off one side of my blowers intake as show here:


    Go nuts and make sure it is airtight.

    On the other side I placed a small piece before installing my prefilter

    blower2.jpg prefilter.jpg
    It might take you some time to find the right amount of intake air to
    block off but this is what you are looking for

    The flow bends a lighter flame over 90 degrees from 1-2 Inches away.


    Mission accomplished.

  3. Professor PinHead

    Professor PinHead Lost in the Tek.... Administrator Mushroom Doctor Cannabis Doctor Supporter

    May 27, 2011
    A Rhizomorphic Space
    :hatsoff: ...........
  4. SEM

    SEM Vendor

    May 31, 2011
    I also did mine almost exactly as you did, but I use a plastic panel on sides and a thick clear palstic over the top. keeps me from sticking my ugly head in to far! The sides are only about 12" sticking out from face of filter so I can slide work past filter easy. I painted inside and use plastic to line inside of box and also use a couple 100 tubes of caulk!
    My other hood uses Pexiglass , and I do like it better than what I used , but not in a hurry to change it. One thing I found out is you have to use wood that isn't too green or pressure treated. I had used some on some shelfs and even painted with mildew resistant paint, couldn't figure where contamination was coming from till I noticed some paint had scraped off and under it was green mold. Spend the mony and get the good wood, certainly on the flow hood! Happy shrooming every one! SEM
  5. EvilMushroom666

    EvilMushroom666 Well-Known Member Moderator Mushroom Doctor

    May 27, 2011
    Plus the satisfaction of building your own hood cannot be matched. I saved easily $350-450 by using a furnace blower instead of an inline blower brand new, and I learned a little bit about motors, plenums, air flow, physics, ect ect. It is a good learning experience and I would recommend to anyone who has even the slightest touch of mechanical inclination to build there own.

    She ain't pretty, but good enough for the girl I go with;-)
  6. Alkaloids

    Alkaloids General Specialist

    Jun 21, 2011
    Deep Space
    You put some good work into that evil. I'm sure it will be even more fun than you would have thought. :) Nice build for sure
  7. EvilMushroom666

    EvilMushroom666 Well-Known Member Moderator Mushroom Doctor

    May 27, 2011
    Thanks brother,

    I love it and I could NEVER go back to working in a glove box as far as agar and culture storage go. I already have plans of building a smaller more portable unit with a front cover to protect the filter in the future.
  8. HorizonSpawn

    HorizonSpawn Moderator Moderator Mushroom Doctor

    Jun 9, 2011
    Truly inspiring! :D
  9. Dr. Hongo

    Dr. Hongo New Member

    May 30, 2011
  10. CharlieBrown

    CharlieBrown Member

    Jan 18, 2012
    This is a great write-up. I am just now finally even getting my head around the concept of a flow hood. A few years ago I thought I would never get serious enough to need one. But now as I get more knowlage and experience I don't see how I could not use one in the future.

    I just built my first glovebox not even 5 months ago, but I'm already sick of the constriction, and the time it takes to do agar work, especially when you have near one hundred or so tranfers to do. It takes hours of clumsy work. It makes it so I pretty much dread all the prep work that needs to be completed just to even start.

    Anyway, enough rambling, I know this is an old thread, but a great write-up none the less.
    I'm saving pennies every paycheck towards the contruction of my own flow hood. Or perhaps even a pre-contructed one, as I am not the most mechanically inclined person. Meanwhile I'll keep practicing in the glovebox, and keep saving that money.
  11. kdmmontana

    kdmmontana Well-Known Member

    Jul 4, 2011
    You know I think that flow hood needs testing from a certified tester. I happen to be one of those:) Why dont you just send me that rascal and ill test it out to make sure it flows correctly:)

    Nice job man!
  12. harponet

    harponet Well-Known Member

    Dec 8, 2011
    Tiphareth; Northern Europe Hardiness Zone 7; Clima
    What about this laminar flow IOt costs only 290 EUR with tax and delivery! I am looking at it now for 3 months. Last month it was available for only a bit more then 200 EUR!
    Just asking because of all your hard work and price isn't that much different...

    317 CAD = 239.57 EUR (Euro)
    Last edited: Feb 12, 2012
  13. kdmmontana

    kdmmontana Well-Known Member

    Jul 4, 2011
    I think its cool that he made it himself, it gives so much more.

    A flowhood is a great tool and it will expand mycology so much. It will be the first thing I buy when I move away:)
  14. harponet

    harponet Well-Known Member

    Dec 8, 2011
    Tiphareth; Northern Europe Hardiness Zone 7; Clima
    It will be the 2nd thing I buy after a new good Android tablet
  15. rogue

    rogue ♥ Hooked on Mycelium ♥ Moderator Mushroom Doctor Supporter

    Jul 15, 2011
    Jefferson State, Hardiness Zone 7B
    I'd stay clear of that flowhood! Em's build is far superior!
  16. Damion5050

    Damion5050 Master Mycologist

    Feb 18, 2012
    Great write up and build !! Flowhood = Winning !!
  17. the spore depot

    the spore depot Vendor

    Mar 2, 2012
  18. mycborg

    mycborg Well-Known Member Supporter

    Mar 3, 2012
    This is not the place you'r looking for
    Is there a reason why the air intake isn't at the back of hoods? I have an inline fan and would like to mount it on the back blowing against the filter. Bad idea? There will be less pressure drop than blowing towards the bottom.
    Only negative I can think of is that maybe it will disturb the laminar flow by doing so.
    What's your thoughts about it?
  19. Ozzy

    Ozzy Ggt's fanboi Moderator Mushroom Doctor Cannabis Doctor

    Aug 20, 2011
    In your bushes
    to produce laminar flow, the fan needs to be mounted 90 degrees away from the filter to build up the static pressure behind it.
  20. mycborg

    mycborg Well-Known Member Supporter

    Mar 3, 2012
    This is not the place you'r looking for
    Ah, so that is why, thanks Ozzy!