|
Some of these posts are very old and might contain outdated information. You may wish to search for newer posts instead.
|
shobimono
Why?
Registered: 09/14/04
Posts: 561
|
walls and lid around front of flow hood?
#6605260 - 02/24/07 10:59 AM (17 years, 2 months ago) |
|
|
I've seen pictures of some flow hoods that have walls and a top (clear plastic for example) in front of the HEPA where you would work.
Is there a benefit to doing this? ie things can't fall into the air flow. Or reasons not to do it? ie if not airtight it will suck in contams or create eddies?
I can understand if you only have a 12" tall HEPA why you might not want to limit your access by blocking the top, but I'm curious to know whether it's worth adding walls and a top?
|
Jeremy_Davis
Mycelial NetworkAdministrator


Registered: 04/22/05
Posts: 652
Loc: Florida
Last seen: 12 years, 1 month
|
Re: walls and lid around front of flow hood? [Re: shobimono]
#6607957 - 02/25/07 08:09 AM (17 years, 2 months ago) |
|
|
Well, here's a picture of our flow hood @ ECHO's mushroom lab.

As you can see, it has both the walls, and the Plexiglas shield. While the shield does keep contams from falling into the HEPA airstream, I think the real reason of the shield is that it creates a smaller space for the airstream to exit the clean area, thereby creating a greater airflow, and increasing the pressure somehow. I've actually tested the airflow using a spray bottle, and just spraying a mist into the airflow with and without the Plexiglas (it's removable), and with the Plexiglas on, the mist is carried almost twice as far on the air current from the HEPA.
Realistically though, I usually work with the Plexiglas off. I jut can reach in better to work, and I just work close up to the filter, and don't have any real problems with the clean work. The filter is 2 x 4 ft or 2 x 3 I can't recall right now...but it works great. Light and Love, JD
-------------------- Jeremy Davis Educational Concerns for Hunger Organization, Inc. Check out the ECHO mushroom blog page to see our lab, growing facility, and more-www.echotech.org/greta
|
RogerRabbit
Bans for Pleasure


Registered: 03/26/03
Posts: 42,214
Loc: Seattle
Last seen: 1 year, 2 months
|
Re: walls and lid around front of flow hood? [Re: Jeremy_Davis]
#6608037 - 02/25/07 08:54 AM (17 years, 2 months ago) |
|
|
Quote:
Jeremy_Davis said: Well, here's a picture of our flow hood @ ECHO's mushroom lab.

Realistically though, I usually work with the Plexiglas off. I jut can reach in better to work, and I just work close up to the filter,
Which is what i would suggest. The sides and top, especially if angled, interrupt the laminar flow. You still have flow, but it's no longer laminar, and could possibly develop eddies within. 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
|
Arp
roving mycophagist


Registered: 04/20/98
Posts: 2,191
Loc: in a van by the river
|
Re: walls and lid around front of flow hood? [Re: RogerRabbit]
#6608050 - 02/25/07 09:02 AM (17 years, 2 months ago) |
|
|
If I were to rebuild mine I would recycle the filtered air.
Im going to attatch a tube to the intake from the side of the workspace on mine. Should work
|
RogerRabbit
Bans for Pleasure


Registered: 03/26/03
Posts: 42,214
Loc: Seattle
Last seen: 1 year, 2 months
|
Re: walls and lid around front of flow hood? [Re: Arp]
#6608100 - 02/25/07 09:27 AM (17 years, 2 months ago) |
|
|
Not recommended. It could create eddy currents and destroy the laminar flow. A flowhood should be used in a small, sealed room anyway, so after it runs the 20 minutes it should run before starting sterile work, the room air is pretty clean and it's what you're recirculating anyway. 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
|
Arp
roving mycophagist


Registered: 04/20/98
Posts: 2,191
Loc: in a van by the river
|
Re: walls and lid around front of flow hood? [Re: RogerRabbit]
#6608129 - 02/25/07 09:43 AM (17 years, 2 months ago) |
|
|
http://www.globalrph.com/aseptic.htm
I was thinking something like the vertical flow hood seen on this link.
|
RogerRabbit
Bans for Pleasure


Registered: 03/26/03
Posts: 42,214
Loc: Seattle
Last seen: 1 year, 2 months
|
Re: walls and lid around front of flow hood? [Re: Arp]
#6608213 - 02/25/07 10:17 AM (17 years, 2 months ago) |
|
|
Nice link. The problem I would see with the vertical hood shown is contaminants from your hands could easily be blown into a petri dish or jar when you first open the lid. I like their horizontal configuration much better, and is similar to what most mycologists use. 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
|
Arp
roving mycophagist


Registered: 04/20/98
Posts: 2,191
Loc: in a van by the river
|
Re: walls and lid around front of flow hood? [Re: RogerRabbit]
#6608504 - 02/25/07 12:14 PM (17 years, 2 months ago) |
|
|
I don't think it's too much of a problem, or I've been extra lucky. I got mine mounted so the draft is mainly from the above but also from the side as it has to go out somewhere.
 ^ my flow hood
|
RogerRabbit
Bans for Pleasure


Registered: 03/26/03
Posts: 42,214
Loc: Seattle
Last seen: 1 year, 2 months
|
Re: walls and lid around front of flow hood? [Re: Arp]
#6608657 - 02/25/07 01:12 PM (17 years, 2 months ago) |
|
|
I think that's a better design than the vertical one in the link above where the air exits the bottom. It just seems that contaminants from our gloves or even the jar or petri dish lid could get knocked into the sterile medium the other way. 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
|
ohmatic
searcher


Registered: 02/28/04
Posts: 6,742
Loc: europe
|
Re: walls and lid around front of flow hood? [Re: RogerRabbit]
#6608786 - 02/25/07 01:59 PM (17 years, 2 months ago) |
|
|
i used to have walls at the side of my flowhood, they really made it hard to work in front of it as the movement with the arms was limited.
i then re-designed it ands its much more confortable now 
OLD:

NEW:
--------------------
MONOTUB tek HEATBOMB tek RIP #cultivation! ....can't associate? well FUCK U !
|
Arp
roving mycophagist


Registered: 04/20/98
Posts: 2,191
Loc: in a van by the river
|
Re: walls and lid around front of flow hood? [Re: ohmatic]
#6608873 - 02/25/07 02:24 PM (17 years, 2 months ago) |
|
|
That is a big filter you've got there dude! I remember you were getting one before my 1y trip but never got to see it. Looks nice
|
ohmatic
searcher


Registered: 02/28/04
Posts: 6,742
Loc: europe
|
Re: walls and lid around front of flow hood? [Re: Arp]
#6608901 - 02/25/07 02:35 PM (17 years, 2 months ago) |
|
|
its great for working with spawnbags
--------------------
MONOTUB tek HEATBOMB tek RIP #cultivation! ....can't associate? well FUCK U !
|
shobimono
Why?
Registered: 09/14/04
Posts: 561
|
Re: walls and lid around front of flow hood? [Re: ohmatic]
#6611512 - 02/26/07 03:56 AM (17 years, 2 months ago) |
|
|
Quote:
ohmatic said: NEW:
I am definately going with a horizontal flow hood.
I've always planned on a flip out bottom shelf to save space, like ohmatic's above.
Thanks for the responses, I think I will stay away from adding a top and sides.
|
RogerRabbit
Bans for Pleasure


Registered: 03/26/03
Posts: 42,214
Loc: Seattle
Last seen: 1 year, 2 months
|
Re: walls and lid around front of flow hood? [Re: shobimono]
#6612119 - 02/26/07 10:57 AM (17 years, 2 months ago) |
|
|
I'd try to find a way to seal that hinge during sterile work. The flow from the filter can cause unsterile air to carburete up through the hinge and mix into the sterile flow. 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
|
shobimono
Why?
Registered: 09/14/04
Posts: 561
|
Re: walls and lid around front of flow hood? [Re: RogerRabbit]
#6612365 - 02/26/07 12:25 PM (17 years, 2 months ago) |
|
|
I was thinking something along the lines of this (shelf on the right side)

using a continuous hinge, not standard door type hinges.
|
Brainiac
Rogue Scientist


Registered: 04/29/06
Posts: 13,259
Loc: 與您的女朋
|
Re: walls and lid around front of flow hood? [Re: Jeremy_Davis]
#6613493 - 02/26/07 05:33 PM (17 years, 2 months ago) |
|
|
 Could this be used like glovebox to ?
--------------------
Fair is Fair
|
fastfred
Old Hand



Registered: 05/17/04
Posts: 6,899
Loc: Dark side of the moon
|
Re: walls and lid around front of flow hood? [Re: Brainiac]
#6613637 - 02/26/07 06:21 PM (17 years, 2 months ago) |
|
|
I've always used microbiology style flow hoods with walls and a movable front. Depending on your flow being laminar for any distance doesn't seem very wise to me. Any drafts or normal air movement and you might have problems.
There are different ideas on what works good, but most of the lab flow hoods I've used don't try to depend on laminar flow for any distance.

Some designs use a fiter the same size as the workspace, others use filters much smaller and constrict the size of the exhaust to be comparable. In the pic above it looks almost like a glove box. I prefer to use the kind with a movable front (called a sash) that goes all the way across rather than having a hand hole type. You just raise the front, put your stuff inside, then lower the front to a comfortable working height. I also prefer the type with a filter that covers the entire top or one with a diffuser after the filter to give more even airflow. The one pictured has a pretty small filter.
Using large HEPA filters makes the flow hoods much more expensive than designs that use small filters and a movable sash.
-FF
|
petridish
gutted mycophile
Registered: 02/23/07
Posts: 47
Last seen: 12 years, 9 days
|
Re: walls and lid around front of flow hood? [Re: fastfred]
#6615716 - 02/27/07 05:50 AM (17 years, 2 months ago) |
|
|
Mine is a modular set up so I can tear it down. It utilizes a fan box with the fan speed control RR pointed me to. It also uses a 2'x4' filter in it's own aluminum box. The two are connected by a section of 16" insulated flexible ducting. When I set this up, I tape a 20" deep shield around the filter. It has two sides and a top and is set up horizontal. My question is, with a 20" cabinet extending straight out from my filter, am I causing myself problems? Can I mist and observe the air to diagnose these problems? I'm going to set up again soon for some clean work and would like to figure out if I'm going about this all wrong. What say you?
|
ohmatic
searcher


Registered: 02/28/04
Posts: 6,742
Loc: europe
|
Re: walls and lid around front of flow hood? [Re: RogerRabbit]
#6616575 - 02/27/07 12:34 PM (17 years, 2 months ago) |
|
|
Quote:
RogerRabbit said: I'd try to find a way to seal that hinge during sterile work. The flow from the filter can cause unsterile air to carburete up through the hinge and mix into the sterile flow. RR
thankx man, ive been quite some agar work in front of that hood now and never had a contamination problem resulting from contaminated air, so the laminar flow does not get disturbed or contaminated.
Quote:
fastfred said:
Using large HEPA filters makes the flow hoods much more expensive than designs that use small filters and a movable sash.
iirc my filter was about 250$ or so - given the confort it provides, that was well worth it.
--------------------
MONOTUB tek HEATBOMB tek RIP #cultivation! ....can't associate? well FUCK U !
Edited by ohmatic (02/27/07 12:35 PM)
|
caricapapaya
Stranger


Registered: 04/10/06
Posts: 258
Last seen: 2 years, 6 days
|
Re: walls and lid around front of flow hood? [Re: ohmatic]
#6617089 - 02/27/07 03:15 PM (17 years, 2 months ago) |
|
|
the type of hood you need depends a lot on what types of things you'll be working with,
The vertical flow hood shown on that link is a biological safety hood, or type of containment hood. They provide inward airflow to prtoect the user, filtered internal air to protect the project, and filtered exhaust so as not to exhaust dangerous stuff into the airspace in the lab,
this would be overkill for mushroom growing, but it works nonetheless.
Plant tissue culture labs use more open designs, but the norm is to have walls and a top.
for general fungal culture, I think we can all see that there are many practical, functional designs, each probably has its strong and weak points, but even inoculations, etc in open air can be successful (although not recommended) a high percentage of the time if one pays attention to basic sterile technique.
that said, I still would like a nice big hepa filter 
carica
|
|