Water Boil Detector

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jollyrgr
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Post by jollyrgr » Tue Oct 30, 2007 9:27 pm

A whistle should work.
Now go do a YAGOOGLE search on the key words MICRO KETTLE and you will see links like:
http://gizmodo.com/gadgets/gadgets/micr ... 177496.php
Note the section where it says this thing can be used on most cups and mugs.

Then head on over to the Home Shopping Network and pick one up for about $8.
http://sale.hsn.com/progressive-micro-k ... 60_xp.aspx

(This is just an example site. Others may have it cheaper.)


If you frequent garage sales and thrift shops, pick up a normal whistling tea kettle that has a PLASTIC whistle. You could probably pick one up for a couple bucks. Extract the whistle and kludge it to the lid of a "microwave safe" dish and go for it. NEVER PLUG UP/SEAL A DISH IN A MICROWAVE! IT CAN EXPLODE!

For my part I have a Pasta and Rice cooker that goes in the microwave. It has a double lid to prevent boil over and still vent. I've used it for probably the last seven years and it works great. I think it was about $7 at Wal-Mart. Go to the HSN and see their item number: 216-955. Much more expensive at HSN but this is the one I have and it works great.
No trees were harmed in the creation of this message. But billions of electrons, photons, and electromagnetic waves were terribly inconvenienced!

rshayes
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Post by rshayes » Wed Oct 31, 2007 12:07 am

The same problem occurs for rice. One solution is to use a measured amount of water. Determine the time at full power required to bring the water up to boiling. At this time, reduce the power to a level that will not cause the water to foam up so much that it boils over. On my oven, this is about the 30% setting. This will keep the water at an average temperature just below the boiling point of water. It foams up slightly during the power on part of the cycle, but when the power cycles off the foam drops down again.

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MrAl
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Post by MrAl » Wed Oct 31, 2007 11:12 am

haklesup:
Yes my oven isnt rated that high so i guess that's why i need the lid.
I dont keep the water boiling really when they are cooking, i just like
to bring it back to a boil after i add the spagetti, then turn the power
down to just keep it hot. It does however take less power to keep hot
with the lid on than with it off, for what it is worth.
Foaming detector sounds interesting too. I could easily build this as
you say. How would i get it to contact the bubbles though if the lid
is on and the pot is rotating with the turntable? BTW, when the pot
is rotating the mix heats more uniformly so i would hate to stop it
from turning. I dont think i can glue it to the inside of the lid
because the pot rotates. Any other ideas about this?
Im not too worried about actually stopping the over electronically,
i dont mind getting up to shut off the oven when the 'alarm' trips
because i would want to set the new time and power setting anyway
as soon as the alarm sounds.

On your last comment about the possibility of not rotating the whole
pot...
Remember that once the water boils (with spagetti in there too) i
turn off the oven and set if for a much lower power setting that
does not cause boiling but simply maintains the heat level. This
means the food does not move much once the lower power setting is
set. The rotation helps keep the heating even during this time.
I could try it i guess without rotating, but i have found in the
past that every food seems to cook more evenly when it rotates
because the waves are more concentrated in one part of the oven
than the other, and by rotating the entire contents of the pot
(or bulk of material) gets subjected to the same energy level.
If it doesnt rotate then some parts of the bulk gets lower
power than others, and it seems to be quite significant (on
the order of a 2 to 1 ratio, or 50 percent for some areas and
100 percent for other areas).

I've also tried careful timing, like say 7 minutes and then shut
off, but with my power line the power getting to the oven varies
quite a bit so the time period to boil with spagetti changes
quite a bit too. In fact, this is how i first found out that
microwave ovens are very sensitive to a change in line voltage,
where the power reduces very greatly with a relatively small
drop in line voltage. It ends up being something like related
to the fourth power of the voltage ratio, but then there is some
point at which no cooking at all takes place (maybe 85 volts).


Ceasar:
Well sometimes i let the water boil more than other times before
i put the spagetti in.
BTW, the foam comes up after the spagetti is inserted and the
water is heated to bring it back to a boil (the spagetti cools
the water down even if it was boiling so it should be brought
back to a boil).

When they say the food is cooked from the inside out i think
what they originally meant was that the heat is generated
*inside* the food, which is really true, but then people started
to think that somehow the heat came from the exact *center* of
the food, which it doesnt unless the food bulk is fairly thin.
Thus, the microwave does cook food from the inside out, but
how deep inside is quite shallow as compared to what most people
would think on hearing that statement.
Also, because most foods have a fairly good amount of bulk
the heat developed in the outer layers of the food still has to
conduct and partly convect into the deeper regions of the food
as im sure you know. Looking at this shows that the heat is
in fact developed *inside* the food itself, but most of the
food gets cooked as a result of conduction and convection.
It's also true that as the moisture content of the outer layers
reduces as the result of heating that the waves can penetrate
deeper and deeper, meaning that the heat layer would move
closer and closer to the center of the food, although there
must be some limit unless the food dries up completely :smile:
LEDs vs Bulbs, LEDs are winning.

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Joseph
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Post by Joseph » Wed Oct 31, 2007 12:15 pm

Hi Al,

I used to make bread with added water. The water aways caused problems in the cooking process. I have since developed a recipe for making dry bread/cereal which requires no added water before cooking in the microwave.

I know it is not really what you have in mind--a solution to pasta making problems. But using flour instead of dehydrated pasta offers some advantages.

One is that you can use whole grain. Pasta is not really something good for us or any mammal to consume. It is little better than white sugar for consumption.

The cooking time is minimized since there is no extra water which has to not only heat, but evaporate and cool the food down.

It is much more satisfying to consume. The body accepts it much better in the whole process ranging from nutrient derivation to waste excretion.

http://groups.yahoo.com/group/Favorite_ ... ly_Living/

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haklesup
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Post by haklesup » Wed Oct 31, 2007 12:26 pm

I hate to say it but jollyrgr trumped us all with the "Microwave Pasta Cooker". I googled it and the customer reviews are really good. I might just get one for all the other stuff you can cook in it.

I agree most foods benefit from rotation. I was just saying foods that are mostly liquid water would have sufficient convection in most cases to skip it. The nature of the boiling point keeps the whole volume at nearly 100C pretty well even if the extra energy to actually boil (the phase change) is not there.

Undrainied spagetti would qualify as mostly water but rice cooked with just the right amount of water would not be that way by the end of the cook time.

I agree with the inside out cooking reasoning but heat cannot convect in solid foods. For convection, the heated media must be able to physically move into a cooler region. Only gasses and liquids convect.

OK now a little fun solution. I call it the door popper. Some of us may have had some fun putting freeze mist or dust off into a film can, sealing the lid, walking off and waiting for the lid to blow off. A variation of this might put a small amount of water into a piston which upon boiling, pushes out and pops the door open. :eek: Yeah, I know it would be hard to calibrate to pasta. Maybe your lid is sealed and the steam ported via a silicone hose. Steam flows freely until mixed with foam upon which a ball stop valve is floated to the closed position allowing pressure to build.

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MrAl
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Post by MrAl » Wed Oct 31, 2007 12:48 pm

Hi again,


rshayes:
i find i have a bit of a problem keeping the water as some fixed
temperature, but after it boils it seems to be ok on power
2 or 3 so i was going it that way. The problem seems to come in
when the water has to come to a boil with the spagetti in it.

Joe:
Well that is interesting but i like to make spagetti sometimes
anyway even if i made that sometimes too.

haklesup:
I'll have to look into that. I saw some at the store too but
didnt like the looks of it. I'll look on the web next.
I could try a small vessel inside the oven with water in it
i guess and when i hear it pop that would tell me, but is this
really better than the control freaks 99 cent sensor (ok more
like 20 bucks ha ha).
LEDs vs Bulbs, LEDs are winning.

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Joseph
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Post by Joseph » Wed Oct 31, 2007 2:52 pm

Hi again Al,
I wonder if you can soak the pasta for a while with just the right amount of water. Then when cooked, it would absorb it before it had a chance to boil over. I like this variation which is similar to ideas mentioned earlier.

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Joseph
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Post by Joseph » Wed Oct 31, 2007 3:07 pm

PS.
Maybe you could speed up the process by heating the pasta for a few minutes but not long enough for boiling. Then it will absorb the water faster.

The double lidded device was a pretty good idea.

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MrAl
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Post by MrAl » Wed Oct 31, 2007 9:44 pm

Hi again,

Well Joe, i sort of have a tried and proven way that i prefer but it
takes a bit of feedback to get right. If i do start trying other things
now that will mean more time consuming experimentation right?
If i can detect the boil i got it working right away. Turns out though
this isnt that easy.
LEDs vs Bulbs, LEDs are winning.

Robert Reed
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Post by Robert Reed » Wed Oct 31, 2007 9:55 pm

Very interesting ideas and suggestions here, but my wife has always used the KISS method - the old fashioned stove top :grin: . Never fails.

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Joseph
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Post by Joseph » Thu Nov 01, 2007 7:17 am

I know what you mean, Al. But sometimes the effort is worth it.

As far as boil detectors go, do you think the humidity sensor is the best option for you?

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MrAl
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Post by MrAl » Thu Nov 01, 2007 12:52 pm

Hi again,


I guess i am still thinking this over. The humidity sensors do have
a bit of a time delay which can be as much as 3 minutes so i have
to figure that in too.
LEDs vs Bulbs, LEDs are winning.

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Joseph
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Post by Joseph » Fri Nov 02, 2007 7:32 am

Hi Al,
three minutes is way to much time lag. It would require just seconds to boil over. I was thinking that maybe a temperature sensor will work.

When the water begins to boil, it gives off a lot of vapor, cooling it down. This vapor would then reach a temperature sensor, heating it up. You could use a very small thermistor with low thermal mass.

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haklesup
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Post by haklesup » Fri Nov 02, 2007 10:29 am

Temperature alone is flawed because as you heat the water it will reach 100C then you need to put more heat in and it will now start to boil and the water will still not exceed 100C with the application of more heat. You can use temp to know when it is about to boil or is boiling but it does not have the resolution to tell the difference. Steam temperature could be higher, hard to say how much under those conditions though

However that may be just what you want, to get back to the oven at the threshold of boiling not after it has started.

Keeping the lid on the pot, would complicate the implementation of a humidity sensor. The tell tale rise in humidity at the BP may be delayed by being entraped by the lid. Only after foaming had begun could enough steam escape to trip the sensor. You would almost need a chart recorder to find the optimal operating conditions and mounting location.

I was joking about the door popper idea. I also would be joking to suggest mouinting a video camera on the door and watching it on picture in picture on the TV while you wait.

I think what the world really needs is a microwave that is easier to clean like all 6 surfaces that remove and are dishwasher safe. I can't imagine cleaning one of those new ovens with the microwave drawer that slides out. The top is inaccessible as far as I can tell

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MrAl
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Post by MrAl » Fri Nov 02, 2007 11:43 am

Hi again,

Joe:
The first think i am going to try is the thermistor mounted outside
the oven to detect air coming out the back. If i can get a reading
that tells me it is 'near' boiling even if not boiling yet that might be
good enough as i will then wait for the rest of the time.

haklesup:
I havent seen any of those new ovens yet. So they have a drawer
instead of a door that opens? Wow that's strange. I wonder what
the advantage if any that has? Personally i like the door.
LEDs vs Bulbs, LEDs are winning.

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