EvilMushrooms Flowhood Build
https://www.shroomery.org/forums/showflat.php/Number/13850394
Did this write up to add to the flowhood section of the main site. I
am looking for any feedback , criticism or corrections.
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 chose 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 community,
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:
NOTE:
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*
-Silicone
-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."-RRSo 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
deal.
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
rescue!
Specs of two HEPA's to choose from:
Tri-Pure HEPA
Standard Cap model
Recommended Airflow = 250FPM(1.25 m/sec)
Resistance
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 Linkshttp://www.orchids.org/conservation/inVitro.htmlhttp://www.orchidsusa.com/1Introduction.htmI 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

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--------------------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
summer.
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
it.


Quote:
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:
Quote:
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
parts.
-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
board.
RR 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

After the cleaning!
--------------------Construction--------------------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.

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.

-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

If all goes well
--------------------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

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.

Helpful Links:
Flowhood Help - Post made in Advanced Mycology, documents my build and
has a LOT of helpful information throughout
https://www.shroomery.org/forums/showflat.php/Number/13327748/fpart/1/vc/1My flowhood - Post I made in cult when I finished my build
https://www.shroomery.org/forums/showflat.php/Number/13458056#13458056