No offense taken regarding the still. It turns me off because anything I 
have fermented or distilled has fallen far below the quality of cheap wine!

You sound very well organized and have done your homework well but you would 
not be the first to underestimate the power of steam.

Heating the whole supply of water is inefficient and dangerous. A separate 
boiler may add a little complexity but will likely be worth the effort.

If you choose to use the pressure cooker as a steam source consider:
    Limit the volume of water in a test cycle to a small amount.
    Fabricate or buy some kind of pop-off regulator that you can adjust to 
your needs to further assure a safe operation.

I consider steam power a sleeping giant that will become a more important as 
the cost of petroleum continues to rise. The Stanley Steamer automobile was 
never refined but the technology is still there.

BTW, model airplane builders sometimes use plastic soda bottles for pressure 
accumulators to operate retractable gear. They burst about 150 psi. Of 
course they will not take the heat of steam. There has to be something in 
the trash pile that will.... Maybe an empty butane container? Don't forget a 
safety pop-off!

John Ferrell    W8CCW
"My Competition is not my enemy"
http://DixieNC.US

----- Original Message ----- 
From: "Peter P." <plpeter2006@yahoo.com>
To: <piclist@mit.edu>
Sent: Friday, November 24, 2006 5:28 AM
Subject: Re: [OT]: Pressure cooker burst disk ?


> John Ferrell <johnferrell <at> earthlink.net> writes:
>
>> A lot of things to consider here...
>> A lot of energy in the kitchen application is radiated. A fiberglass
>> jacket would save a lot of energy loss.
>
> I agree, and for a sun collector even more so.
>
>> A six quart pressure cooker filled to 4 quarts takes about 10 minutes on
>> "high"  to come up to pressure, it takes half power to maintain pressure
>> with a minimal "hiss".
>
> Ok, 4 quarts ~= 3.7 liters, with 4.2J/g*K and dT=100K in 600 seconds is
> about 2.6kW in. I assume this is an electrical heater ?
>
>> 15 pounds of pressure may not seem like much but when it is superheated
>> water a sudden breach releases a lot of energy. A smaller pressure vesell
>> would minimize the risk.
>
> I agree. The pressure cooker I had in mind was the small kind, 2 liters 
> capacity.
>
>> I cannot recommend a pressure  cooker for anything other than its 
>> intended
>> use. It excels as a cooking tool.
>
> Yes, but this is an engineering-related list ;-) ;-) Also making a 
> pressure
> and heat-proof boyler from scratch is much harder than adapting something 
> like
> a pressure cooker.
>
> Sorry about the joke about the distillation use.
>
> Please see attached photos of a 10 Watt 2 in. impulse turbine I built in 
> 2002. This would run on Victorian steam with a different nozzle. It 
> requires 2.2-2.5 bars for optimal operation. It has a shunt type voltage 
> regulator that also prevents turbine overrevving (by loading it down), but 
> not overtemperature. Air consumption is about 1l/sec at 3bar with 8.1 W 
> out on load (9Vdc at 0.9A into 10 Ohms - this exceeds the limits of the 
> generator slightly, the turbine is not the limiting factor here).
>
> thanks,
> Peter
>
> PS: The photos did not go through, sending them 1 by 1
>
>
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