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Sockadin



Registered: 01/03/10
Posts: 7,244
Last seen: 2 months, 20 days
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Re: My Sterile Room [Re: Hobbyist]
#26486537 - 02/15/20 05:41 AM (3 years, 11 months ago) |
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That thing looks cool. Just don't fruit any oysters in there or the walls will go white with spores. This is one of those things I would end up building while I am waiting for jars to colonize or tubs to start to get ready to fruit. It is a great way to pass time and put in energy and focus, but overall it isn't as needed if you have a flowhood. I use to do all my agar work in one I built in my shed.
I didn't know azur got banned.. TO bad, I kinda liked his attitude.
Staments has produced more information and understanding of Mycology than any of us ever will. I have nothing bad to say about him.
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PTreeDish


Registered: 04/22/18
Posts: 353
Last seen: 3 months, 15 days
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Re: My Sterile Room [Re: Hobbyist]
#26487788 - 02/16/20 12:59 AM (3 years, 11 months ago) |
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Thanks man. Re: positive pressure. wiki defines it as:
Quote:
Positive pressure is a pressure within a system that is greater than the environment that surrounds that system.
When the zipper is open, the force of the fan pushes air into the prechamber, lowering the pressure of the sterilized room and increasing the pressure of the prechamber. This positive pressure would remain until the force of the fan was overcome by the outside air pressure.
Given the volume of the clean room and the fact that the zipper is both narrow and never open for more than a few seconds, wouldn't that pretty much ensure that most of the time, there is positive pressure into the unsterilized prechamber space?
The clean room would be in a slight vacuum when I zip the door up but would recede when the fan went off and outside could slowly leak in and/or I leave the door open.
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Sockadin



Registered: 01/03/10
Posts: 7,244
Last seen: 2 months, 20 days
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Re: My Sterile Room [Re: PTreeDish]
#26487922 - 02/16/20 06:45 AM (3 years, 11 months ago) |
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I agree that if you don't have an area for the air to go into your flowhood from outside you don't have positive pressure.what is happening is when running the floowhood your slowly drawing air into your tent blowing it up probably via the zipper door. Otherwise you just have forced air moving around the inside of your tent. Plus you want laminar flow, so if your floowhood is blowing hard enough to create positive pressure with stagnat air inside, enough to force air out when you open the Zipper you might have to much flow to create laminar flow.
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Hobbyist
Citizen


Registered: 08/15/10
Posts: 805
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Re: My Sterile Room [Re: PTreeDish]
#26489337 - 02/17/20 02:30 AM (3 years, 11 months ago) |
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Quote:
PTreeDish said: Thanks man. Re: positive pressure. wiki defines it as:
Quote:
Positive pressure is a pressure within a system that is greater than the environment that surrounds that system.
When the zipper is open, the force of the fan pushes air into the prechamber, lowering the pressure of the sterilized room and increasing the pressure of the prechamber. This positive pressure would remain until the force of the fan was overcome by the outside air pressure.
Given the volume of the clean room and the fact that the zipper is both narrow and never open for more than a few seconds, wouldn't that pretty much ensure that most of the time, there is positive pressure into the unsterilized prechamber space?
The clean room would be in a slight vacuum when I zip the door up but would recede when the fan went off and outside could slowly leak in and/or I leave the door open.
You are correct in the quote you posted, however: If you think in terms of sealed systems it might be easier to explain.
Imagine your clean room is an actual room and airtight. Now, put your flow hood in the room(or any fan). Your clean room in it's current state with all the equipment and air inside it can be considered a sealed system. If you turn on the fan with the room sealed and secure, you will move around the air in the room and create turbulence and moving air inside that room, but you will only be moving the air that's already inside that room. As you have not introduced anything additional to the sealed system, there's no reason to think that the pressure inside would be greater.
Since you aren't introducing any additional air, you won't be creating and pressure, just air currents. In order to increase the pressure in the room, you must add to the contents of the room, change the temperature of the room, or change the room's volume in some way.
Since the only thing you're doing is creating airflow with your flow hood you aren't creating pressure, you're simply moving air.
However
If you'd like to create positive pressure it would be easy: adjust your setup so your flow hood pulls air from outside your clear room. Try it and consider the difference. I wager your plastic clean room becomes bubble-esque with the positive pressure.
If you have your flow hood intake draw air from outside the clean room, you will be adding all the air your flow hood filters to the clean room, thus increasing the volume of air for the given volume of the room creating positive pressure.
-------------------- Everything i say is completely hypothetical...
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Kizzle
Misanthrope


Registered: 08/30/11
Posts: 9,855
Last seen: 3 hours, 26 seconds
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Re: My Sterile Room [Re: PTreeDish]
#26489579 - 02/17/20 07:51 AM (3 years, 11 months ago) |
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Quote:
PTreeDish said: Stamets book recommended a proper clean room having up to 4 entrances before entering the final room. So in my model, I created a still air entrance room that is about 4x4 that houses the zip wall. So it's basically one additional place to minimize introducing dirty attic air.
When entering the first entrance, there is 70% IPA and gloves to wipe myself down and everything around me down. When I unzip the main entrance, positive pressure from the hood running inside minimizes the introduction of additional contams upon entry.
I've also taken measures to clean and sterilize the pathway I take outside of the tent to get to it. Finally, I have some degree of climate control in this room and have the flexibility of tapping an outside air source and directing it only into this space when needed.
Is any of this necessary? I don't know but I could not, in good conscience, simply work in the open air of my attic.
Not really. Because the air coming out of the flow hood is moving in a nice straight line, assuming it's working properly, you don't actually need any kind of physical barrier around that area to keep contaminants out. The movement of the air itself prevents contaminated air from surrounding area from entering the area directly in front of the hood. So when you're using a FH all you really need to worry about it your sterile technique because even though the air coming out of the hood is practically sterile the surfaces of the objects you're placing into that air flow are not. The main cause of contamination is going to be handling things in a way that allows a nonsterile surface, like your hand, to come between the front of the hood and a sterile surface, like the inside part of a petri or jar lid.
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rm1024
Familiar Stranger
Registered: 11/05/18
Posts: 62
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Re: My Sterile Room [Re: Kizzle]
#26489650 - 02/17/20 08:58 AM (3 years, 11 months ago) |
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PTreeDish


Registered: 04/22/18
Posts: 353
Last seen: 3 months, 15 days
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Re: My Sterile Room [Re: rm1024]
#26490987 - 02/18/20 12:39 AM (3 years, 11 months ago) |
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Appreciate the clarification on positive pressure and the value (or lack thereof) in a confined space for sterility. There other benefits to the enclosed space, like keeping the attic dust and mold out, but good to know it's really the sterile laminar flow and sterile technique that matter most.
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