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 worowa
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 Fan Fliter Unit vs Flow Hood 
#16352646 - 06/08/12 06:02 PM (11 months, 6 days ago) |
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I've been checking out some of these units, heaps of varieties,
http://www.alibaba.com/product-gs/551219294/Cleanroom_FFU.html
seems like they'ld make a quick and cheap flow hood replacement, and way more portable.
Any one used them, or have any comments?
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 a social revolt
retired cultivator
Registered: 09/07/11
Posts: 833
Loc: Brooklyn, NYC 
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Re: Fan Fliter Unit vs Flow Hood [Re: worowa]
#16353823 - 06/08/12 11:16 PM (11 months, 6 days ago) |
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is the hepa 99.99%?
and how fast does the air blow?
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worowa
Professor
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Yeah, sorry, wrong link.
This one has the data specs. 99.99 at .3microns, wind speed .35-.6m/s
http://www.alibaba.com/product-gs/457597182/High_Efficiency_Fan_Filter_Unit_Air.html
Lots of similar ones on that site, and flow hoods.
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 Nobitte
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Re: Fan Fliter Unit vs Flow Hood [Re: worowa]
#16354231 - 06/09/12 12:40 AM (11 months, 6 days ago) |
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Sound almost identical to the specs for a flow good, if you are able to get the 99.99% filtration out of it, it might be a viable alternative, being a lazy rich bitch, i use a fungi perfecti premade one, works like a charm, but this could be a cheap alternative.
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Then... WE CAN TEACH 
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a social revolt
retired cultivator
Registered: 09/07/11
Posts: 833
Loc: Brooklyn, NYC
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Re: Fan Fliter Unit vs Flow Hood [Re: worowa]
#16355513 - 06/09/12 11:45 AM (11 months, 5 days ago) |
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Quote:
worowa said:
Yeah, sorry, wrong link.
This one has the data specs. 99.99 at .3microns, wind speed .35-.6m/s
http://www.alibaba.com/product-gs/457597182/High_Efficiency_Fan_Filter_Unit_Air.html
Lots of similar ones on that site, and flow hoods.
Ok... yeah, that seems fine to use... I don't even own a flowhood, but I was planning on building one soon, hence why I know about how they work and stuff..
but I would need advice from a pro before buying anything 
EDIT: Hey- ask a mod to move this thread to the cultivation forum, or re-post it yourself- I bet you'll get more opinions/answers there!
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Edited by a social revolt (06/09/12 11:47 AM)
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Terry M
Stranger in a Strange Land
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Re: Fan Fliter Unit vs Flow Hood [Re: worowa]
#16356176 - 06/09/12 02:58 PM (11 months, 5 days ago) |
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Quote:
worowa said:
Yeah, sorry, wrong link.
This one has the data specs. 99.99 at .3microns, wind speed .35-.6m/s
http://www.alibaba.com/product-gs/457597182/High_Efficiency_Fan_Filter_Unit_Air.html
Lots of similar ones on that site, and flow hoods.
I'm very skeptical that this can produce laminar flow. In addition to high air filtration, you need laminar flow in a laminar flow hood! The filter doesn't seem thick enough to do this. The whole unit is only 69mm deep? That's only 2 3/4 inches. It may be perfectly good for clean room air filtration. However that's necessarily but not sufficient for a flow hood.
Regards,
Terry
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Liberté, égalité, humidité.
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OICU812
Chefs Choice Mushroom Co.
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Re: Fan Fliter Unit vs Flow Hood [Re: Terry M]
#16360901 - 06/10/12 02:27 PM (11 months, 4 days ago) |
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The power required is 220V/50Hz. In the USA, all electrical current is 60Hz. Either you are in Europe or you will need a 60Hz to 50Hz Frequency Converter.
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"Human beings, who are almost unique in having the ability to learn from the experiences of others,
are also remarkable for their apparent disinclination to do so." - Douglas Adams
“Experience is the best teacher . . . and fools will
learn from no other" - my Grandmother
Forget injuries, never forget kindnesses. - Confucius
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OICU812
Chefs Choice Mushroom Co.
Registered: 11/06/11
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Last seen: 7 hours, 31 minutes
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Re: Fan Fliter Unit vs Flow Hood [Re: Terry M] 1
#16361226 - 06/10/12 03:49 PM (11 months, 4 days ago) |
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Quote:
Terry M said:
Quote:
I'm very skeptical that this can produce laminar flow. In addition to high air filtration, you need laminar flow in a laminar flow hood! The filter doesn't seem thick enough to do this. The whole unit is only 69mm deep? That's only 2 3/4 inches. It may be perfectly good for clean room air filtration. However that's necessarily but not sufficient for a flow hood.
Terry: One of us is confused about the concept of laminar flow. I don't think it has any thing to do with filter thickness.
How a laminar flow hood functions
Laminar and Turbulent Flow
Laminar flow From Wikipedia, the free encyclopedia
As I understand it, it's more about containing the flow of air after it exits the filter to obtain high momentum diffusion and low momentum convection.
Your thoughts?
Edited by OICU812 (06/10/12 07:32 PM)
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worowa
Professor
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Re: Fan Fliter Unit vs Flow Hood [Re: OICU812]
#16362000 - 06/10/12 06:44 PM (11 months, 4 days ago) |
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Quote:
OICU812 said:
The power required is 220V/50Hz. In the USA, all electrical current is 60Hz. Either you are in Europe or you will need a 60Hz to 50Hz Frequency Converter.
Australia actually.
Nice links, espeially the first one.
I realise the FFU is not necessarily laminar flow, and doesn't have a hood, but check out the Mushworld Oyster Mushroom book, p.65.
I wonder how important laminar flow actually is? As soon as our hands or equipment enters the air flow, the air would become turbulent-wouldn't it?
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OICU812
Chefs Choice Mushroom Co.
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Re: Fan Fliter Unit vs Flow Hood [Re: worowa]
#16362348 - 06/10/12 08:10 PM (11 months, 4 days ago) |
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Quote:
worowa said:
I wonder how important laminar flow actually is? As soon as our hands or equipment enters the air flow, the air would become turbulent-wouldn't it?
Laminar flow is important across the working surface, ie.: the open petri dish, culture tube, or other open container. One does not come between the open vessel and the air flow. This allows pure contaminate-free air to be "pushing away" the contaminates from the work.
No, it isn't perfect, contaminates still do find their way into our work, but it is mainly due to sloppy procedure or mistakes rather than free floating contaminates.
Yes, the first link, How a laminar flow hood functions is a great one, and does a fantastic job of exemplifying the simplicity of a laminar flow hood.
Best of luck!
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"Human beings, who are almost unique in having the ability to learn from the experiences of others,
are also remarkable for their apparent disinclination to do so." - Douglas Adams
“Experience is the best teacher . . . and fools will
learn from no other" - my Grandmother
Forget injuries, never forget kindnesses. - Confucius
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Terry M
Stranger in a Strange Land
Registered: 06/18/10
Posts: 1,354
Loc: Rhode Island
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Re: Fan Fliter Unit vs Flow Hood [Re: OICU812]
#16362741 - 06/10/12 09:16 PM (11 months, 4 days ago) |
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Quote:
OICU812 said:
Terry: One of us is confused about the concept of laminar flow. I don't think it has any thing to do with filter thickness.
...
As I understand it, it's more about containing the flow of air after it exits the filter to obtain high momentum diffusion and low momentum convection.
Nope. The filter must create the laminar flow. It does this by passing the filtered air through an array of small (and very fragile) corrugated aluminum guides on its exit side. All laminar flow HEPA filters have this. It's responsible for part of the depth of the filter.
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Liberté, égalité, humidité.
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OICU812
Chefs Choice Mushroom Co.
Registered: 11/06/11
Posts: 716
Loc: Foothills of NC
Last seen: 7 hours, 31 minutes
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Re: Fan Fliter Unit vs Flow Hood [Re: Terry M]
#16362916 - 06/10/12 09:50 PM (11 months, 4 days ago) |
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Quote:
Nope. The filter must create the laminar flow. It does this by passing the filtered air through an array of small (and very fragile) corrugated aluminum guides on its exit side. All laminar flow HEPA filters have this. It's responsible for part of the depth of the filter.
I am unable to find data on that. Can you supply?
Are you referring to HEPA-SEP?
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"Human beings, who are almost unique in having the ability to learn from the experiences of others,
are also remarkable for their apparent disinclination to do so." - Douglas Adams
“Experience is the best teacher . . . and fools will
learn from no other" - my Grandmother
Forget injuries, never forget kindnesses. - Confucius
Edited by OICU812 (06/10/12 10:57 PM)
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Terry M
Stranger in a Strange Land
Registered: 06/18/10
Posts: 1,354
Loc: Rhode Island
Last seen: 8 hours, 59 minutes
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Re: Fan Fliter Unit vs Flow Hood [Re: OICU812]
#16363306 - 06/10/12 11:14 PM (11 months, 4 days ago) |
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Quote:
OICU812 said:
Quote:
Nope. The filter must create the laminar flow. It does this by passing the filtered air through an array of small (and very fragile) corrugated aluminum guides on its exit side. All laminar flow HEPA filters have this. It's responsible for part of the depth of the filter.
I am unable to find data on that. Can you supply?
It's not data, but a branch of physics known as fluid dynamics.
The effect of the array of narrow passages is to create small diameter tubes. This decreases the Reynolds number of the flow. When the diameters are small enough for a given velocity (for a flow hood, 100 feet per minute), the Reynolds number is below about 2300. Then the flow is laminar.
If the opening has no tubes and is just an "orifice," flow with a very high Reynolds number is created. High Reynolds number necessarily means turbulent flow, which is the opposite of laminar flow.
Hope this helps. I can't really go into any more detail without getting into some hardcore physics. Google "Reynolds number" and you will learn more.
Regards,
Terry
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Liberté, égalité, humidité.
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a social revolt
retired cultivator
Registered: 09/07/11
Posts: 833
Loc: Brooklyn, NYC
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Re: Fan Fliter Unit vs Flow Hood [Re: Terry M]
#16365302 - 06/11/12 12:51 PM (11 months, 3 days ago) |
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Wow, you really know your shit, Terry M.
I have a few hundred together right now and am learning as much as I can about laminar flowhoods before I buy the parts and build one myself.
What do you think about StoneSun's flowhood build?
Cause I really like his and it's size, so I'd figured I'd follow that tek (would be much easier than starting from scratch myself)
Meanwhile.... keep having this conversation guys! 
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Terry M
Stranger in a Strange Land
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Quote:
a social revolt said:
Wow, you really know your shit, Terry M.
It helps to have a sound undergraduate science and math education. There's stuff that you pick up that you'll use for the rest of your life. I have no particular expertise in flow hoods -- I just understand the scientific principles that make them work.
Quote:
What do you think about StoneSun's flowhood build?
Looks great to me!
My own flowhood was a carpenter's nightmare. Not only did it leak, but it looked like hell because of the ill-fitting joints and the screw holes which couldn't quite be covered over with plastic wood.
But then I discovered the wonders of decorative duct tape. I painted the exterior wood flat black, and covered all the edges neatly with shiny black duct tape. Now it's air-tight, and it actually looks like I planned to make it look that way! 
Regards,
Terry
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Liberté, égalité, humidité.
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OICU812
Chefs Choice Mushroom Co.
Registered: 11/06/11
Posts: 716
Loc: Foothills of NC
Last seen: 7 hours, 31 minutes
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Re: Fan Fliter Unit vs Flow Hood [Re: Terry M]
#16367704 - 06/11/12 11:13 PM (11 months, 3 days ago) |
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Quote:
Terry M said:
It's not data, but a branch of physics known as fluid dynamics.
The effect of the array of narrow passages is to create small diameter tubes. This decreases the Reynolds number of the flow. When the diameters are small enough for a given velocity (for a flow hood, 100 feet per minute), the Reynolds number is below about 2300. Then the flow is laminar.
If the opening has no tubes and is just an "orifice," flow with a very high Reynolds number is created. High Reynolds number necessarily means turbulent flow, which is the opposite of laminar flow.
Hope this helps. I can't really go into any more detail without getting into some hardcore physics. Google "Reynolds number" and you will learn more.
Regards,
Terry
Actually, that is incorrect. In the 1880s, Osbourne Reynolds in an experiment which has become a classic in fluid mechanics found that the RATE of flow of a fluid could be determined to be laminar, transitional or turbulent by using the formula: Re=pud/u
where r = density, u = mean velocity, d = diameter and p = kg/m3. This value is known as the Reynolds number, Re:
Laminar flow: Re < 2000
Transitional flow: 2000 < Re < 4000
Turbulent flow: Re > 4000
Reynolds number is an expression of the RATE of flow of a viscus fluid through a given size vessel and has nothing to do with shape. I hold a BSME from NCSU. The reference for this data can be found here: Laminar and Turbulent Flow
Just to be sure, I verified my information today with Jimmy Harris, engineer at Flanders Filters where my 22 HEPA and ULPA filters came from. PM me if you would like to have his phone number.
Laminar Flow is a specific RATE of flow of air from the filter, usually 90-110 SFM with the pleated HEPAs we use due to air's viscosity, and has nothing to do with the depth (or width depending on perspective) of the filter, nor the corrugated aluminum pleat separators of a HEPA-SEP.
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"Human beings, who are almost unique in having the ability to learn from the experiences of others,
are also remarkable for their apparent disinclination to do so." - Douglas Adams
“Experience is the best teacher . . . and fools will
learn from no other" - my Grandmother
Forget injuries, never forget kindnesses. - Confucius
Edited by OICU812 (06/11/12 11:58 PM)
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Terry M
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Re: Fan Fliter Unit vs Flow Hood [Re: OICU812]
#16369022 - 06/12/12 05:52 AM (11 months, 3 days ago) |
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Quote:
OICU812 said:
Quote:
Terry M said:
It's not data, but a branch of physics known as fluid dynamics.
The effect of the array of narrow passages is to create small diameter tubes. This decreases the Reynolds number of the flow. When the diameters are small enough for a given velocity (for a flow hood, 100 feet per minute), the Reynolds number is below about 2300. Then the flow is laminar.
If the opening has no tubes and is just an "orifice," flow with a very high Reynolds number is created. High Reynolds number necessarily means turbulent flow, which is the opposite of laminar flow.
Hope this helps. I can't really go into any more detail without getting into some hardcore physics. Google "Reynolds number" and you will learn more.
Regards,
Terry
Actually, that is incorrect. In the 1880s, Osbourne Reynolds in an experiment which has become a classic in fluid mechanics found that the RATE of flow of a fluid could be determined to be laminar, transitional or turbulent by using the formula: Re=pud/u
where r = density, u = mean velocity, d = diameter and p = kg/m3. This value is known as the Reynolds number ...
There's a little more to it than that. See the d = diameter? That's technically "hydraulic diameter," and is identical to diameter only for a round pipe. There's a formula for getting the hydraulic diameter for other cross-section shapes. It's determined by the cross-sectional area and the perimeter. The shape of the corrugations doesn't matter. Only the fact that they have small cross-sections. The d is in the numerator of the equation you gave, so the Reynolds number is directly proportional to it.
If you do the math you'll find that the Reynolds number of 100 fpm air flow through the entire open front area of the flow hood (on the scale of "d" above) is huge, many times the under 2300 necessary for laminar flow. But when you constrict the air to the scale of a few mm, which the small corrugations do, then you get to a sufficiently low Reynolds number at 100 fpm for laminar flow. I measured my flow hood holes, and they can be approximated by a d of 4mm.
PS
I was curious and did the math.
A d of 4mm gives a low Reynolds number of 133, for nice laminar flow.
A d of 2 feet, the scale of a flow hood opening, gives a Reynolds number of 19979, well into the turbulent range.
Edited by Terry M (06/12/12 01:49 PM)
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Javadog
Continuing along
Registered: 05/03/10
Posts: 7,286
Loc: USA
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Re: Fan Fliter Unit vs Flow Hood [Re: Terry M]
#16380440 - 06/14/12 01:18 PM (11 months, 17 hours ago) |
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Good stuff Terry. Thanks for taking the time.
I was going to ask OICU to ask his engineer "why the pleats are used,
unless it was to ensure laminar flow?" (seemed to me to be a better
way at the distinction he was suggesting), but your response obviated the need.
I had not taken it down to the physics, and your perspective seems clear.
JD
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OICU812
Chefs Choice Mushroom Co.
Registered: 11/06/11
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Last seen: 7 hours, 31 minutes
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Re: Fan Fliter Unit vs Flow Hood [Re: Javadog]
#16382685 - 06/14/12 10:01 PM (11 months, 8 hours ago) |
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Quote:
Javadog said:
I was going to ask OICU to ask his engineer "why the pleats are used,
unless it was to ensure laminar flow?"
JD
Aluminum pleats are designated by the identifier HEPA-SEP and they are used to keep the filter pleats separated, thus the suffix "SEP".
John Holliday advises against them in his lectures as they have the tendency to create micro tears in the filter media that can not be repaired.
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"Human beings, who are almost unique in having the ability to learn from the experiences of others,
are also remarkable for their apparent disinclination to do so." - Douglas Adams
“Experience is the best teacher . . . and fools will
learn from no other" - my Grandmother
Forget injuries, never forget kindnesses. - Confucius
|
Javadog
Continuing along
Registered: 05/03/10
Posts: 7,286
Loc: USA
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Re: Fan Fliter Unit vs Flow Hood [Re: OICU812]
#16382815 - 06/14/12 10:35 PM (11 months, 8 hours ago) |
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Quote:
OICU812 said:
John Holliday advises against them in his lectures as they have the tendency to create micro tears in the filter media that can not be repaired.
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Boyd Rice told my brother that life is a corny pack of freesakes
Myco-tek.org
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