autoclave built from modded espresso machine

[Mackenzie Cowell]

According to this wonderful video, http://www.vimeo.com/8709313,
espresso machines routinely produce 135 pounds of steam pressure. So
I wonder, has anyone tried modding a cheap espresso machine into an
autoclave? Would it be "too dangerous"?

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[Bigvolcano]

Love the video- I wanna coffee!

Sent from my iPhone

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[khedges1]

What would be the advantage over a pressure canner? I don't know if an
espresso machine could make enough steam to pressurize something big
reasonably quickly. However, you can get pressure canners in volumes
from 16 to 41 quarts.

16-qt for $50
http://www.amazon.com/Presto-16-Quart-Aluminum-Pressure-Cooker/dp/B000QJJ9NY/ref=sr_1_3?ie=UTF8&s=home-garden&qid=1264277996&sr=8-3

41-qt for $350
http://www.amazon.com/All-American-2-Quart-Pressure-Cooker-Canner/dp/B0002808ZM/ref=sr_1_8?ie=UTF8&s=home-garden&qid=1264277996&sr=8-8
(I think the multiple clamps on the All-American definitely give it
some Mad Science ambience.)

Of course, there are lots of intermediate sizes. I don't know about
urban areas, but out here in the boonies, you can find them at any
hardware store in the housewares section to get an idea of what the
sizes look like. You might find some used, though a quick check of
SFBay Craigslist gave me what looked like a very old corroded pressure
cooker for $200... don't recall the size, though.

You'd need a heat source, such as a kitchen stove (preferably gas), or
a hotplate (for the small ones) or propane burner (for large ones,
outdoors).

I haven't used one yet for low-acid pressure canning (too busy with
grad school, alas). I got a 16-qt Presto at an estate sale for $35
(before I knew new ones were only $50).

I don't know if you could do a safe but rapid blowdown for dry
materials. (Otherwise, you end up with moisture in items like boxes of
pipet tips.) But they'd work fine for agar and liquid media.

Note: "Steam canners" are not pressurized.
http://www.amazon.com/Back-to-Basics-Steam-Canner/dp/B0000DDUCJ/ref=sr_1_1?ie=UTF8&s=home-garden&qid=1264278708&sr=8-1

--Kathryn

On Jan 22, 4:20 pm, Mackenzie Cowell <m...@diybio.org> wrote:
> According to this wonderful video,http://www.vimeo.com/8709313,

[Cathal Garvey]

Forgive me if I'm mistaken, but the pressure in an autoclave is simply a prerequisite for the desired temperature of 115-125C, right? As in, without containing the steam, you can't get it to superheat, and containing it generates pressure as a matter of course.

However, the steam frother on a coffee machine pumps out pre-heated steam that could well exceed 100C anyway, so although it'd likely be a wasteful approach you could try routing that steam into container with a small vent, and see does it heat the chamber to the desired "wet" 115-125C, without requiring containment or any potentially dangerous modification to the coffee machine.

If anyone has one of these machines on-hand, they could try it out on some autoclave tape and/or cultures and let the list know?
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[Meredith L. Patterson]

On Mon, Jan 25, 2010 at 12:09 PM, Cathal Garvey <cathal...@gmail.com> wrote:
> However, the steam frother on a coffee machine pumps out pre-heated steam
> that could well exceed 100C anyway, so although it'd likely be a wasteful
> approach you could try routing that steam into container with a small vent,
> and see does it heat the chamber to the desired "wet" 115-125C, without
> requiring containment or any potentially dangerous modification to the
> coffee machine.

The real question is whether the rerouted steam would maintain its
temperature for the half-hour recommended for pressure autoclaving.

--mlp

[Cathal Garvey]

Or even for that matter its pressure, considering how long even the professional machines take to get up to speed. It mightn't be very practical, but for a quick fix I'd love to know if it were possible.

2010/1/25 Meredith L. Patterson <clon...@gmail.com>

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[Mackenzie Cowell]

What's the difference between an autoclave and a pressure sterilizer?

My impression is that autoclaves have a reservoir of pre-heated, pre-pressurized steam ready to flood the sterilization chamber, whereas pressure sterilizers create the steam pressure during the run.

But I don't think it's that simple.  I'd like to find a book about this.  "Introduction to Sterilization Techniques" or something.

Mac