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wise_gardener
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Registered: 08/02/05
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Blower recommandation ? Need 510 m3/hour at 300 Pa!
#6140801 - 10/06/06 03:18 PM (17 years, 7 months ago) |
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Hi, I just buy a 24x18 hepa filter (0.8" static pressure) from fungi perfecti with a coarse prefilter (0.2" static pressure estimated). I need a blower that will deliver 510 m3/hour at 300 Pa. Does somebody have a squirrel cage blower brand to recommend me ? I want a low noise blower if possible. I'm looking for a online vendor in north America too. Any help will be appreciated.. thanks wise_gardener
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BIGSWANG
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: wise_gardener] 1
#6140809 - 10/06/06 03:21 PM (17 years, 7 months ago) |
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dayton makes the best squirell cage blowers imo.... i use a 495 cfm and it does of course omit some noise..but compared to the crapy one i got off ebay..its 10x quiter
go with dayton...you wont be disapointed
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creamcorn
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: BIGSWANG]
#6140871 - 10/06/06 03:42 PM (17 years, 7 months ago) |
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haha and being the nerd i am... a tip, you can multiply cfm by 1.7 to get m3/h... soo 495cfm would be more than you need (though you could rig it up on a light switch dimmer and make it adjustable!)
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BIGSWANG
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: creamcorn]
#6140894 - 10/06/06 03:50 PM (17 years, 7 months ago) |
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Quote:
creamcorn said: haha and being the nerd i am... a tip, you can multiply cfm by 1.7 to get m3/h... soo 495cfm would be more than you need (though you could rig it up on a light switch dimmer and make it adjustable!)
yes...a light switch dimmer will actually help with the noise alot too..if you get a high power dayton fan...you can run it at half power ....causing lower rpm...in turn making your fan quiter
i think i got mine for around 100 bucks...]
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SpookerShroom
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Registered: 06/12/06
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: creamcorn]
#6140895 - 10/06/06 03:51 PM (17 years, 7 months ago) |
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I also wouldn't use a SC for that. Inline centrifugal fans are much better for any pressure applications. And a lot, lot quieter.
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BIGSWANG
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: SpookerShroom]
#6140921 - 10/06/06 03:58 PM (17 years, 7 months ago) |
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Quote:
SpookerShroom said: I also wouldn't use a SC for that. Inline centrifugal fans are much better for any pressure applications. And a lot, lot quieter.
100% correct
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wise_gardener
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: BIGSWANG]
#6140954 - 10/06/06 04:10 PM (17 years, 7 months ago) |
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I'm a little bit confused about the cfm rating of blower. Almost every blower I found online don't provide a complete data sheet for the cfm/static pressure ratio. They online provide the cfm of the blower in free air (I think ?). 495 cfm will not give the same output beside an 1" static pressure hepa filter... :\
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SpookerShroom
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: wise_gardener]
#6141019 - 10/06/06 04:39 PM (17 years, 7 months ago) |
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http://rewci.com/fafxseincefa.html
That is a link to some centrifugal fans, which I would recommend for use with pressure application, especially with 1 inch SP.
The second chart has the CFM listings for different static pressures about halfway down the page.
It looks like for 1 inch SP you would want a FX10XL, which would put out 394 cfm @ 1 inch SP
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wise_gardener
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: SpookerShroom]
#6141030 - 10/06/06 04:43 PM (17 years, 7 months ago) |
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Great, that's what I'm looking for.. thanks a lot!
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RogerRabbit
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: wise_gardener]
#6141123 - 10/06/06 05:24 PM (17 years, 7 months ago) |
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You better be ready to get out your checkbook if you plan to use one of those inline duct fans. The only one that could possibly be suitable is the 12" model, their largest. It's rated at 655 CFM at 1" of static pressure, and costs $350. You can get a suitable squirrel cage blower at Graingers for less than half that.
You CAN NOT use a lighting dimmer to control an inductive load. Such is an extreme fire hazard, a violation of article 430 of the National Electrical Code, and guaranteed to burn out any motor under load in a very short time. To control motors, you need a motor speed controller. They come in both voltage and frequency control styles.
An 18 X 24 filter will require at least 750 CFM at 1" WC to work properly. You have 3 square feet of surface area. To get an airspeed of 100 feet per minute(the very minimum that will work) leaving the filter, you'd have to have 300 CFM delivered with no loss. Such is impossible. There is resistance causing loss as the air leaves the blower. There is resistance causing loss as the air makes the turn into the plenum. There is resistance causing loss as the air pressurizes the plenum, and there are losses introduced by resistance as the air travels through the filter. Thus, a 300 cfm blower will not deliver 300 cfm after all that.
I use a 12 X 24 flowhood with a 650 CFM blower and it's barely enough. The airspeed leaving my flowhood has been measured at 118 lineal feet per minute. I doubt seriously that would be able to deliver the minimum 100 feet per minute with the 20% more surface area of your filter. RR edited to fix typos
-------------------- Download Let's Grow Mushrooms semper in excretia sumus solim profundum variat "I've never had a failed experiment. I've only discovered 10,000 methods which do not work." Thomas Edison
Edited by RogerRabbit (10/06/06 06:42 PM)
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SpookerShroom
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: RogerRabbit]
#6141272 - 10/06/06 06:16 PM (17 years, 7 months ago) |
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Very good point RR, I forgot to mention that about the dimming switches, I've seen pictures of a few burnt up electical boxes from people doing that.
Also, and I know you are more knowlegable about this than me so I'll make it more of a question....While the squirel cage blowers are alot cheaper, they don't do as well when it comes to pressure, and their airflow/pressure ratios are much worse, therefore you would need a much higher cfm SC blower to get the same CFM after the filter, than you would an inline,...does that make any sense?
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RogerRabbit
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: SpookerShroom]
#6141289 - 10/06/06 06:24 PM (17 years, 7 months ago) |
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No. The inline blowers are MUCH less effecient. They save the contractor money on installation because they fit right into the duct system, and the business or homeowner pays for it forever with higher energy costs.
By the way, the inline fans are squrrel cage type. They just have far fewer blades than a normal squirrel cage blower will have. They're for high cfm, low load applications such as exhaust fans. When put under static pressure, the cfm drops substantially. You can see that information if you pull up the pdf document on the engineering specs. RR
-------------------- Download Let's Grow Mushrooms semper in excretia sumus solim profundum variat "I've never had a failed experiment. I've only discovered 10,000 methods which do not work." Thomas Edison
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wise_gardener
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: SpookerShroom]
#6141294 - 10/06/06 06:29 PM (17 years, 7 months ago) |
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RogerRabit, I need 300 cfm at 1" static pressure, not 750.. ? I have 3 square feet of surface area, not 5.. Here how I calculate from Anno table :
Static pressure of Hepa filter : 0.8" Static pressure of the pre-filter : 0.2" Total static pressure : 1"
Air speed of the air flowing from the filter surface needed : 100 feet per minute
Filter surface : 2ft x 1.5ft = 3 ft2
Multiply air speed by area of the filter : 100 ft/min x 3 ft2 = 300 ft3/min
300 ft3/min = 300 cfm
1 cfm = 1.7 m3/h
Then my blower must deliver 300 cfm (510 m3/h) at a pressure static of 1" (300 Pa)
I'm not sure how you calculated 750 cfm.. please explain yourself
Source : http://www.fungifun.org/English/Flowhood
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RogerRabbit
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: wise_gardener]
#6141317 - 10/06/06 06:39 PM (17 years, 7 months ago) |
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Sorry, the 5 square feet was a brain fart. However, 300 cfm won't cut it due to the losses involved. My flowhood is 2 square feet and has a 650 cfm blower that is barely enough. Add the extra 1/3 surface area, and it works out to 750 cfm to get the same speed I have which will bend the flame of a bic lighter over 45 to 90 degrees, but not blow it out.
Sorry, I had too many things going on at once as I typed earlier and got sidetracked. I still stand by the 750 cfm. You can get one from Grainger for around $150. RR
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wise_gardener
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: wise_gardener]
#6141319 - 10/06/06 06:39 PM (17 years, 7 months ago) |
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I think your misunderstand for the filter surface area. I just read about resistance causing loss. I'm not sure what to think. Anno did not mention anything about that on his website and even choose a lower fan cfm (about 10%) than needed as it's the closed between the 4 in his example chart to fit his need.
For the inline blower that his much less efficient, I have look at data spec of each filter, and the 10" Fantech FX 10 deliver 300 cfm at 1" static pressure, please explain why it would not deliver it ? :\
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RogerRabbit
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: wise_gardener]
#6141338 - 10/06/06 06:48 PM (17 years, 7 months ago) |
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Because 1" static pressure covers only the filter itself. There are other losses involved as stated above. You also need to remember those figures are for a brand new filter. As it gets clogged up, you need to allow for that as well.
As said above, my 12 X 24 flowhood is perfect with a 650 cfm blower. I wouldn't shoot for the minimum size that could possibly work. You can always throttle down the output by blocking off part of the intake. RR
-------------------- Download Let's Grow Mushrooms semper in excretia sumus solim profundum variat "I've never had a failed experiment. I've only discovered 10,000 methods which do not work." Thomas Edison
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SpookerShroom
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: RogerRabbit]
#6141397 - 10/06/06 07:29 PM (17 years, 7 months ago) |
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Quote:
RogerRabbit said: Because 1" static pressure covers only the filter itself. There are other losses involved as stated above. You also need to remember those figures are for a brand new filter. As it gets clogged up, you need to allow for that as well.
As said above, my 12 X 24 flowhood is perfect with a 650 cfm blower. I wouldn't shoot for the minimum size that could possibly work. You can always throttle down the output by blocking off part of the intake. RR
Cheaper than a speed controller too 
Also, I did some research after you corrected me on the pressure/cfm ratios of both, and found that you were right, but only in respect to the smaller (<400cfm) fans. All of the inline centrifugal blowers had a MUCH more gradual airflow drop as pressure increased, than the equivalent cfm (0.000 in. SP) SQ blowers in the 400cfm+ range.
For comparison: Fantech FX12XL / Dayton SC Blower (815cfm)
0.000 in.SP 801cfm / 815cfm 0.500 in.SP 729cfm / 537cfm 0.750 in.SP 692cfm / 250cfm 1.000 in.SP 655cfm / ------
So, as the data shows, the inline centrifugal blower's airflow drops off much slower than the SC blower airflow does at the same givin pressures. The SC blower doesn't list a MAX pressure, but the data for it only goes up to .75 inSP so Im guessing that right around .8-.85 inSP is the MAX pressure. Also he stated he wants a very quiet blower which inlines are known for.
Not trying argue, and you were right the smaller <400cfm SC fans actually outperformed the inline centrifugal fans by the same amount as the later outperformed the SC fans in the >400cfm range. So considering this data, to get the CFM he needs for that filter he would need a very very large SC blower that would be quite loud and not as inexpensive as your previously mentioned.
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Anno
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: RogerRabbit]
#6142128 - 10/07/06 12:13 AM (17 years, 7 months ago) |
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Quote:
RogerRabbit said: There is resistance causing loss as the air leaves the blower. There is resistance causing loss as the air makes the turn into the plenum. There is resistance causing loss as the air pressurizes the plenum
All those losses are very minuscule compared to the pressure loss at the filter and prefilter. Thus, if you are only taking into consideration the static pressure of the filter and the prefilter, you your calculations are sufficiently correct.
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rungi
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Re: Blower recommandation ? Need 510 m3/hour at 300 Pa! [Re: RogerRabbit]
#7038731 - 06/12/07 04:52 PM (16 years, 11 months ago) |
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Can you use a variable transformer?
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