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: 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."-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 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 Links http://www.orchids.org/conservation/inVitro.html http://www.orchidsusa.com/1Introduction.htm 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 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-------------------- 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 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 After the cleaning!