Lab "Extractor" Bench

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Russ Garrett

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Jun 2, 2011, 7:52:38 PM6/2/11
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This is not an extractor at all - quite the reverse. It's a Faster Air
"horizontal laminar flow" cabinet. It sucks air in from the outside,
passes it through a large HEPA filter, and pushes it out from the back
of the cabinet. This results in the air in the cabinet being quite
pure to avoid contamination of the samples inside it - it's billed as
the alternative to having a clean room. Nifty piece of kit.

I think it's pretty useless for the Hackspace. I doubt we'll need
anywhere near that purity, and (regardless of how we position it) it
will take up an intrusively large part of the wet room.

These things do seem to be quite expensive (a new one is upwards of
£2k), so I suggest we re-list it - correctly - on ebay, perhaps with a
reserve of £50 or so, and hopefully we'll get a decent profit out of
it.

Any objections?

--
Russ Garrett
ru...@garrett.co.uk

Philippe Bradley

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Jun 3, 2011, 4:01:08 AM6/3/11
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I wish we'd figured that out before spending a few hours trying to
reverse the motors!

Avoiding contamination of samples could actually get pretty important
if we start making cultures (I have no idea if the biohacking group
has this in mind, but I imagine it would be great to work on algal
biofuels for example).

Because our ability to (legally) add resistance genes (so we can grow
them in the presence of an antibiotic, for example, that would kill
unwanteds) is going to be limited unless we formally announce such
intentions to the HSE (and take steps to enforce elfansafety). So we'd
have to buy them in a resistant form, which isn't very 'DIY'.

That said, I can't see this design of cabinet either being appropriate
for the tiny room it's in (the horizontal airflow gets interrupted and
refluxed by a wall right behind the experimenter). And it would blow
smells and other solvents (maybe flammable) through the door and into
the wider workshop.

What would be useful if we're actually going to handle things that are
alive (it is "bio"hacking after all...) is an easily cleaned lab bench
that we can irradiate with nasty UV every so often to keep it
decontaminated. And a gas outlet for a bunsen burner (which creates
vertical laminar flows from the rising hot air which you can work
under). And an autoclave for glassware.

Charles Yarnold

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Jun 3, 2011, 5:01:45 AM6/3/11
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On 3 June 2011 00:52, Russ Garrett <ru...@garrett.co.uk> wrote:
...

Any objections?

Not from me! 

Russ Garrett

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Jun 3, 2011, 5:30:24 AM6/3/11
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(Incidentally, here's a diagram of how a HLF cabinet works:
http://www.faster-air.com/cms/img/vetrina/128_3.jpg)

On 3 June 2011 09:01, Philippe Bradley <philb...@gmail.com> wrote:
> That said, I can't see this design of cabinet either being appropriate
> for the tiny room it's in (the horizontal airflow gets interrupted and
> refluxed by a wall right behind the experimenter). And it would blow
> smells and other solvents (maybe flammable) through the door and into
> the wider workshop.

Both good points as well. It's also worth noting that the ebay
description said the filter needed changing. (Which I suspect is not
cheap.)

Apparently if you're using solvents or anything else hazardous, you
need a vertical laminar flow cabinet so you don't end up blowing
everything towards the experimenter (diagram:
http://www.faster-air.com/cms/img/vetrina/127_3.jpg).

--
Russ Garrett
ru...@garrett.co.uk

Mike

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Jun 3, 2011, 5:35:18 AM6/3/11
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On Fri, Jun 03, 2011 at 10:30:24AM +0100, Russ Garrett wrote:
>
> Apparently if you're using solvents or anything else hazardous, you
> need a vertical laminar flow cabinet so you don't end up blowing
> everything towards the experimenter (diagram:
> http://www.faster-air.com/cms/img/vetrina/127_3.jpg).
>

We could hack our horizontal cabinate in to a vertical cabinate by
rotating through 90 degrees.

Mike.

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Philippe Bradley

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Jun 3, 2011, 6:19:01 AM6/3/11
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a vertical cabinet's not much better IMHO: you need extraction of
fumes from inside to outside the room, whereas with your suggestion
you still have the opposite.

One suggestion might be to see if the engines/blowers can be mounted
90 deg (so their inlet goes where their outlet currently is)... The
room would be drawing in dusty air from the workshop, but at least it
would filter it before putting it through the motors and then
releasing it to the outside world. If this worked, you could also
maybe mount a screen to work under (usually leaving a 20cm gap to
slide your arms under). This would be good to protect the face from
splashes, and the equipment from spittle; a side-effect, I suppose,
would be to concentrate the airflow to the area close to the bench
surface, which might be a benefit, but I think you'd still work under
a bunsen for sterile work. Still, I dunno if that's sensible. If the
filter's ineffective, you might still have chemicals going through
motors not designed to be on the receiving end of fumes; that's a fire
hasard, let alone a corrosion risk.

Kal

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Jun 3, 2011, 6:29:06 AM6/3/11
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I have been staring at a similar recirculating cupboard at work for
the last few days and it only just struck me, was surprised to see
this post already here but it's good that we've made sense of the
problem.

My first concern was the cost of the filters, considering that we have
easy access to the outside for extraction, and that we won't be using
anything too nasty, my vote would be to get rid of this current
cupboard and get a halfsized proper extraction one. Instead of paying
for the filters.

I am not sure this is something I would be happy being 'hacked' as it
is essentially a big piece of safety equipment.
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Sam Kelly

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Jun 3, 2011, 6:32:26 AM6/3/11
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Drawing in air from the workshop will kill the filters in very short order, and they're not cheap IIRC.

Having a sterile environment for people to work in would certainly be nice, but it would be much, much nicer to have a box which will stop solvent fumes getting into the open lab. I'm unusually sensitive to them after an industrial accident, but they're still not at all good for anyone else, so I'd suggest that that should be our priority. (Also, if the solvent fumes build up enough, either in the lab or inside equipment not designed for it - which is entirely possible in a long work session - then it's not impossible for them to flash over.)

Standard lab fume cupboards aren't entirely effective (we should do the smokebomb test when we do get something) but it's still far better than nothing.

Sam
--
Sam Kelly, http://www.eithin.co.uk/

That's it.  We're not messing around anymore, we're buying a bigger dictionary.  -  Tibor Fischer, The Thought Gang.

Nicholas FitzRoy-Dale

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Jun 3, 2011, 7:39:12 AM6/3/11
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On 03/06/2011, at 9:01 AM, Philippe Bradley wrote:

> I wish we'd figured that out before spending a few hours trying to
> reverse the motors!

Indeed, though it's nice to know that we were not going mad.

I think it's going to be too big to do anything useful with in the wet room. Perhaps the fan unit could be repurposed for fume extraction. They are pretty great fans.

Otherwise ebay is looking good.

Nicholas

Sam Cook

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Jun 3, 2011, 8:44:22 AM6/3/11
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One suggestion might be to see if the engines/blowers can be mounted
90 deg (so their inlet goes where their outlet currently is)...

I don't think this is possible as the inlets and outlets on the fans have different profiles (20cm circle Vs 20x30 rectangle) also I expect these fans wont work as very good extracts and will likely clog...

Phil suggested using them to drive an extraction system where by the fans essentially create a vacuum in the main ductwork to extract the air that way (I can't remember the name of the effect this employs). 

As is this bench could be used for clean room work and electronics/soldering etc.

As to extraction: what hazardous fumes are people planning to create? AFAIK most of the stuff being done for bio-hacking is reasonably benign as is darkroom work. If people really want to mess with stuff where we need industrial grade fume cabinets then I think a better fitted out location than we have (certainly a larger one) will be required. No matter how good the extraction I would not want to work with hazardous fumes in a room that small. 

Extraction of some sort will be useful in the wetlab but there seems to be a fairly large gulf between what people are proposing and what we will likely need, something similar to the system clearing the laser cutter will probably be sufficient as the main aims (I assume) are to keep clean air circulating and keep the dust down. 

As to supplying clean air into the wetlab (i.e. not from unit 23) either we can a) carefully reposition/modify the outlet for the laser cutter or use a pipe that brings in air from a higher point (possibly with a hood that only takes air from the side furthest from the laser outpipe) or we can pull it in from the quiet room...

Frankly though I think if we can get £2k for it on eBay that's probably the best option (especially with funds as they are) maybe we can use part of it to buy some nice equipment or infrastructure (i.e. the bits for the kitchen & plumbing in darkroom). 

</42 cents>

S

Philippe Bradley

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Jun 3, 2011, 9:10:26 AM6/3/11
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amx109

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Jun 3, 2011, 9:30:26 AM6/3/11
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I don't think this is possible as the inlets and outlets on the fans have different profiles (20cm circle Vs 20x30 rectangle) also I expect these fans wont work as very good extracts and will likely clog...


someones already proposed setting up the fans to extract air using the venturi effect. would bypass the clogging/putting-bad-air-through-the-fan issue

cepm...@yahoo.co.uk

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Jun 3, 2011, 10:14:15 AM6/3/11
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Or alternatively use a fan to draw air into the room from outside creating
an overpressure. If a hood with a largish duct is provided terminating
about two metres above the inlet then the air will follow the path of
least resistance taking any fumes with it and there should be no re-entry
of fume. A by-product of this scheme is that the slight overpressure will
prevent the ingress of dust from the workshop via the spaces round the
door etc. This scheme is used on AFVs to keep out nasty things.

Mike

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Jun 6, 2011, 5:07:23 AM6/6/11
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On Fri, Jun 03, 2011 at 09:01:08AM +0100, Philippe Bradley wrote:
> I wish we'd figured that out before spending a few hours trying to
> reverse the motors!
>

I wish I'd listened to you when you said "It's not meant to blow is it?"!

Mike.

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tom

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Jun 6, 2011, 11:24:16 AM6/6/11
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how laminar is the flow? I'd like to try injecting smoke into it...
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Mike

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Jun 6, 2011, 11:37:10 AM6/6/11
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On Mon, Jun 06, 2011 at 08:24:16AM -0700, tom wrote:
> how laminar is the flow? I'd like to try injecting smoke into it...
>

We have a smoke machine, so please be our guest.

I'd hazard not very laminar currently as shortly after leaving the fan
the air promptly meets the wall, some 30 cms from the edge of the table.

Mike.

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