Date:         Fri, 10 Sep 2010 08:50:59 -0700
Reply-To:     Alistair Bell <albell@SHAW.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Alistair Bell <albell@SHAW.CA>
Subject:      Re: microwave oven
In-Reply-To:  <20100910103303.5QQKS.1774583.imail@eastrmwml31>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

I do have experience and knowledge of steam sterilisation.

To truly qualify in the game, the vessel needs to be able to contain
1 bar (14.7 psi) pressure, at that point temp. will be 121 C. If
items to be sterilised are small, and I am guessing they are, then 20
min at 121C and 1 bar, will sterilise.

Timing started after temp and pressure at above values.

Anything less than that is not sterilisation, sanitised maybe, but
not sterilised.

I am assuming that OP needs are for sterilising equipment rather than
liquids etc. I have no data on the effectiveness of microwave ovens
in sterilising equipment. Some talk about how they can be used to
sanitise sponges etc. Obviously metal equipment can't be used in oven.

If it was me that had this need, I'd spend the money on a pressure
cooker with a gauge and internal rack, (with the supplies to be
sterilised on rack above the water). I'd feel confident in this.

alistair



On 10-Sep-10, at 7:33 AM, Dave Mcneely wrote:

I'm not certain that the device shown is meaningfully different from
similar devices from the same manufacturer, but sold less expensively
as "pressure canners."  It includes an internal sterilizing rack, but
that item is sold separately also.  I had a colleague who taught
workshops for high school teachers on laboratory microbiology
practices.  He taught them to use a Presto or All American (same
company, essentially same equipment) pressure canner for
sterilization (because an autoclave is such a large, expensive piece
of equipment).  I think instruction on how to use a pressure canner
for sterilization can be gotten from other sources -- check with home
health services for example.  Here is the web site for Presto - All
American.   Of course, the consequences of the material not being
sterile might be much greater for you than for high school students
growing microbial cultures for class projects.

http://www.pressurecooker-canner.com/prprca.html

I also wonder if it would not be much more practical to just carry
packaged and sterile stuff with you, but then I don't know and am not
asking what you are sterilizing.

David McNeely

---- David Beierl <dbeierl@ATTGLOBAL.NET> wrote:
> At 08:42 PM 9/9/2010  -0700, Paul and Catherine Lemiuex wrote:
>> We need to install a microwave oven in order to sterilize medical
>> supplies so we can continue camping in our 1990 Westy.   Having
>> trouble finding a microwave that will work with a second battery and
>> inverter.  Does anyone have any experience, suggestions or comments?
>
> Running a microwave from Vanagon batteries would be tough.  This
> small 600-watt oven, for example
> http://www.haieramerica.com/en/product/MWM6600RW uses 950 watts of
> power.  That means give or take one hundred amperes out of your
> battery, and to support that kind of draw you should have 300 (for
> AGM or gel batteries) or 400 (for conventional batteries) amp-hours
> of battery capacity so as not to damage the batteries from too fast a
> discharge.
>
> I think you'd be much better off looking into a steam sterilizer that
> you can run off the stove.  IIRC the stove burners are rated at 5600
> BTU/hr each, which is the same or slightly larger than a regular
> stove burner.  A full propane tank should give you in the area of 48
> hours burning time for one burner.
>
> Here's a ten-quart one at a not-too-outrageous price:
> http://www.amazon.com/All-American-9-5-Quart-Pressure-Sterilizer/dp/
> B000S8G1TS
>
> Yours,
> DAvid

--
David McNeely