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In article <491ECBD7.CE5CFC94@hotmail.com>,
Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:

Don Bruder wrote:

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
ratman wrote:
DaveC <me@privacy.net> wrote:

I know this subject of "cheap" and "calibrate" used in the same
sentence
may well be anathema to some of you but I need to verify that either
my IR
temp gun is accurate or my DMM/thermocouple is, or neither. Accuracy
to 2
or 3
degrees F is fine.

I'm looking for suggestions for a simple way to provide some kind of
common temperature "standard" (I use the term loosely, here) I can
compare
these
against.

I would put money on the therocouple thermometer, for what
it's worth.

I used to 'calibrate' thermocouples by putting them in boiling water.

The classic method, taught to me for checking/calibrating the lab
thermometers in HS chemistry class:

0C/32F = nice tall glass of icecubes allowed to stand and melt long
enough to give you sufficient liquid water to take a reading.

100C/212F = nice cup of rolling-boil water at 1 standard atmosphere

Might not have been *PERFECT*, but it was at least reasonably close
enough for the stuff we were doing.

And that's normally good enough ! Best ignore the change in boiling point vs
atm
pressure. ;~)

Graham
Click to expand...
Since my HS (and the county it was in) was only about 200 feet above sea
level, the error at the high end was generally small enough to be
ignored. YMMV if you went to school in Denver... :)

This was high school science, fergawdsake, not the LHC! :)

--
Don Bruder - dakidd@sonic.net - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info
 
On Sat, 15 Nov 2008 13:17:11 +0000, Eeyore wrote:
And that's normally good enough ! Best ignore the change in boiling point
vs atm pressure. ;~)
Click to expand...
Best not - even cookbooks account for the difference. It takes longer to
boil and egg in Denver than it does in, say, LA.

Hope This Helps!
Rich
 
On Sat, 15 Nov 2008 14:54:15 +0000, Jan Panteltje wrote:
I JUST USED TO HOLD THE SENSOR IN MY HAND AND SET FOR 37.5°C.
Click to expand...
Then it's very likely calibrated wrong. With that "calibrated" sensor,
check the temp. under your tongue, or even in your armpit, to see what
I'm talking about. Of course, we all know which kind of thermometer is
most accurate of all medical thermometers, don't we? >:->

And what's all the shouting about?

Thanks,
Rich
 
On Sat, 15 Nov 2008 14:54:15 GMT, the renowned Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Sat, 15 Nov 2008 14:42:56 +0000) it happened IanM
Invalid@totally.invalid> wrote in <gfmmvv$1ap7$1@energise.enta.net>:

Spehro Pefhany wrote:

On Sat, 15 Nov 2008 13:17:11 +0000, the renowned Eeyore
rabbitsfriendsandrelations@hotmail.com> wrote:



Don Bruder wrote:


Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:

I used to 'calibrate' thermocouples by putting them in boiling water.

100C/212F = nice cup of rolling-boil water at 1 standard atmosphere

Might not have been *PERFECT*, but it was at least reasonably close
enough for the stuff we were doing.

And that's normally good enough ! Best ignore the change in boiling point vs atm
pressure. ;~)


A bit of knowledge can be dangerous...

http://www.ucl.ac.uk/sts/chang/boiling/index.htm

Which is why I reccomended condensing steam on a metal block. Avoids
all sorts of problems with superheat. Once you've done that, might as
well use the same block in melting ice for consistancy.

I JUST USED TO HOLD THE SENSOR IN MY HAND AND SET FOR 37.5°C.
Click to expand...
Got a fever? Hands tend to be pretty cool compared to internal body
temperature, more so on some people than others.

You'd do much better by sticking it umm.. somewhere more ummm..
consistent in temperature...


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
On a sunny day (Sat, 15 Nov 2008 11:24:45 -0500) it happened Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote in
<mqtth4hd7bnnqdtglhattibrodkqv5cohf@4ax.com>:

I JUST USED TO HOLD THE SENSOR IN MY HAND AND SET FOR 37.5°C.

Got a fever? Hands tend to be pretty cool compared to internal body
temperature, more so on some people than others.
Click to expand...
If you are working a lot then hands are not so cold.
Some people always have cold hands ...

You'd do much better by sticking it umm.. somewhere more ummm..
consistent in temperature...
Click to expand...
Oh, yes, in mouth or up ....
But it works very well.
 
On a sunny day (Sat, 15 Nov 2008 16:19:32 GMT) it happened Rich Grise
<rich@example.net> wrote in <pan.2008.11.15.16.19.23.568473@example.net>:

On Sat, 15 Nov 2008 14:54:15 +0000, Jan Panteltje wrote:

I JUST USED TO HOLD THE SENSOR IN MY HAND AND SET FOR 37.5°C.

Then it's very likely calibrated wrong. With that "calibrated" sensor,
check the temp. under your tongue, or even in your armpit, to see what
I'm talking about. Of course, we all know which kind of thermometer is
most accurate of all medical thermometers, don't we? >:-

And what's all the shouting about?
Click to expand...
I AM GLAD YOU ASKED THAT. SIMPLE:
CAPS HAVE ONE BIT LESS SET, SO IT SAVES ON ENERGY.

Thanks,
Rich
Click to expand...
 
On Sat, 15 Nov 2008 14:54:15 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Sat, 15 Nov 2008 14:42:56 +0000) it happened IanM
Invalid@totally.invalid> wrote in <gfmmvv$1ap7$1@energise.enta.net>:

Spehro Pefhany wrote:

On Sat, 15 Nov 2008 13:17:11 +0000, the renowned Eeyore
rabbitsfriendsandrelations@hotmail.com> wrote:



Don Bruder wrote:


Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:

I used to 'calibrate' thermocouples by putting them in boiling water.

100C/212F = nice cup of rolling-boil water at 1 standard atmosphere

Might not have been *PERFECT*, but it was at least reasonably close
enough for the stuff we were doing.

And that's normally good enough ! Best ignore the change in boiling point vs atm
pressure. ;~)


A bit of knowledge can be dangerous...

http://www.ucl.ac.uk/sts/chang/boiling/index.htm

Which is why I reccomended condensing steam on a metal block. Avoids
all sorts of problems with superheat. Once you've done that, might as
well use the same block in melting ice for consistancy.

I JUST USED TO HOLD THE SENSOR IN MY HAND AND SET FOR 37.5°C.
Click to expand...

Skin temp is typically significantly lower than actual internal body
temp.

When body temp is normal 98.6 F, your hand will be at like 91 F
 
On Sat, 15 Nov 2008 16:35:30 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Sat, 15 Nov 2008 16:19:32 GMT) it happened Rich Grise
rich@example.net> wrote in <pan.2008.11.15.16.19.23.568473@example.net>:

On Sat, 15 Nov 2008 14:54:15 +0000, Jan Panteltje wrote:

I JUST USED TO HOLD THE SENSOR IN MY HAND AND SET FOR 37.5°C.

Then it's very likely calibrated wrong. With that "calibrated" sensor,
check the temp. under your tongue, or even in your armpit, to see what
I'm talking about. Of course, we all know which kind of thermometer is
most accurate of all medical thermometers, don't we? >:-

And what's all the shouting about?

I AM GLAD YOU ASKED THAT. SIMPLE:
CAPS HAVE ONE BIT LESS SET, SO IT SAVES ON ENERGY.

Thanks,
Rich



NO, it does not "save" anything. Particularly energy.
Click to expand...

If you published ten GB of data as all caps ASCII text, THEN you MIGHT
save a few milliwatts.

Since we merely write a few lines, the amount of energy used is quite
large, comparatively, and quite wasteful in all cases where one has only
written a few lines.

The less data that a computer actually processes per unit time, the
more wasteful they are, and below a certain point, the computer is at an
"idle state" from a consumption POV for all tasks performed that are not
heavy CPU intensive tasks..

In other words, the GUI and overhead for your machine means that unless
you are actually crunching numbers furiously in a process that actually
taxes the machine, the little petty bits of "work" you perform all use
the same amount of energy per unit of machine time.
 
On Sat, 15 Nov 2008 16:31:26 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Sat, 15 Nov 2008 11:24:45 -0500) it happened Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote in
mqtth4hd7bnnqdtglhattibrodkqv5cohf@4ax.com>:

I JUST USED TO HOLD THE SENSOR IN MY HAND AND SET FOR 37.5°C.

Got a fever? Hands tend to be pretty cool compared to internal body
temperature, more so on some people than others.

If you are working a lot then hands are not so cold.
Some people always have cold hands ...

You'd do much better by sticking it umm.. somewhere more ummm..
consistent in temperature...

Oh, yes, in mouth or up ....
But it works very well.
Click to expand...

In your most comfortable, fuzzy, warm feeling day, your hands are
several degrees cooler than your actual body temp. PERIOD.

IR medical thermometers get pointed into the back of your ear canal for
a reason. If your hands matched you body in temperature, they would be
pointing such instruments at much more accessible locations. They do
not.
 
On Sat, 15 Nov 2008 16:16:33 GMT, Rich Grise <rich@example.net> wrote:

On Sat, 15 Nov 2008 13:17:11 +0000, Eeyore wrote:

And that's normally good enough ! Best ignore the change in boiling point
vs atm pressure. ;~)

Best not - even cookbooks account for the difference. It takes longer to
boil and egg in Denver than it does in, say, LA.

Hope This Helps!
Rich
Click to expand...

If boiling point goes up with reduced atmospheric pressure, then why
does water boil as one approaches a vacuum at room temp?
 
On Sat, 15 Nov 2008 10:07:31 -0800, the renowned Archimedes' Lever
<OneBigLever@InfiniteSeries.Org> wrote:

On Sat, 15 Nov 2008 16:16:33 GMT, Rich Grise <rich@example.net> wrote:

On Sat, 15 Nov 2008 13:17:11 +0000, Eeyore wrote:

And that's normally good enough ! Best ignore the change in boiling point
vs atm pressure. ;~)

Best not - even cookbooks account for the difference. It takes longer to
boil and egg in Denver than it does in, say, LA.

Hope This Helps!
Rich


If boiling point goes up with reduced atmospheric pressure, then why
does water boil as one approaches a vacuum at room temp?
Click to expand...
Cooking time, not boiling point, goes up. How long would eggs take to
cook at room temperature?


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
On Sat, 15 Nov 2008 16:35:30 +0000, Jan Panteltje wrote:
I AM GLAD YOU ASKED THAT. SIMPLE:
CAPS HAVE ONE BIT LESS SET, SO IT SAVES ON ENERGY.
Click to expand...
Well, it's rude.

Albeit, this does kind of open the door to a very thinly veiled
rejoinder:

OK, then. If you want the most accurate reading you can get on your own
body temperature, stick your thermocouple up your ass.

'Bye.
Rich

[Or, just do it on GPs! -- The Pig Bladder From Uranus]
 
On Sat, 15 Nov 2008 13:21:08 -0500, Spehro Pefhany wrote:
On Sat, 15 Nov 2008 10:07:31 -0800, the renowned Archimedes' Lever
On Sat, 15 Nov 2008 16:16:33 GMT, Rich Grise <rich@example.net> wrote:
On Sat, 15 Nov 2008 13:17:11 +0000, Eeyore wrote:

And that's normally good enough ! Best ignore the change in boiling
point vs atm pressure. ;~)

Best not - even cookbooks account for the difference. It takes longer to
boil and egg in Denver than it does in, say, LA.

If boiling point goes up with reduced atmospheric pressure, then why
does water boil as one approaches a vacuum at room temp?

Cooking time, not boiling point, goes up. How long would eggs take to cook
at room temperature?
Click to expand...
Who said the boiling point goes up?? It takes longer to boil an egg in
Denver because the boiling point is _*LOWER*_ with lower atmospheric
pressure.

The "Boiling point" is the temperature at which the vapor pressure reaches
atmospheric pressure."

Hope This Helps!
Rich
 
Don Bruder wrote:

Eeyore wrote:

And that's normally good enough ! Best ignore the change in boiling point vs
atm pressure. ;~)

Since my HS (and the county it was in) was only about 200 feet above sea
level, the error at the high end was generally small enough to be
ignored. YMMV if you went to school in Denver... :)

This was high school science, fergawdsake, not the LHC! :)
Click to expand...
LOL !

I've heard that the UK has had as low as 945 mbar during storms. Now, since
aircraft barometric altimeters only adjust down to 942 mbar IIRC, that's awfully
close to getting a heavy landing or an unwanted float ( mind needs to think which
way it would go if it went below 942 local ) unexpectedly. Good thing that
commercials have radio altimeters.

Graham
 
Archimedes' Lever wrote:

Rich Grise <rich@example.net> wrote:
Eeyore wrote:

And that's normally good enough ! Best ignore the change in boiling point
vs atm pressure. ;~)

Best not - even cookbooks account for the difference. It takes longer to
boil and egg in Denver than it does in, say, LA.

If boiling point goes up with reduced atmospheric pressure, then why
does water boil as one approaches a vacuum at room temp?
Click to expand...
I expect that's simply liberation of dissolved air.

Graham
 
Spehro Pefhany wrote:

the renowned Archimedes' Lever wrote:
Rich Grise <rich@example.net> wrote:
Eeyore wrote:

And that's normally good enough ! Best ignore the change in boiling point
vs atm pressure. ;~)

Best not - even cookbooks account for the difference. It takes longer to
boil and egg in Denver than it does in, say, LA.

If boiling point goes up with reduced atmospheric pressure, then why
does water boil as one approaches a vacuum at room temp?

Cooking time, not boiling point, goes up. How long would eggs take to
cook at room temperature?
Click to expand...
Depends if you like them soft or hard.

Graham
 
Rich Grise wrote:

On Sat, 15 Nov 2008 13:21:08 -0500, Spehro Pefhany wrote:
On Sat, 15 Nov 2008 10:07:31 -0800, the renowned Archimedes' Lever
On Sat, 15 Nov 2008 16:16:33 GMT, Rich Grise <rich@example.net> wrote:
On Sat, 15 Nov 2008 13:17:11 +0000, Eeyore wrote:

And that's normally good enough ! Best ignore the change in boiling
point vs atm pressure. ;~)

Best not - even cookbooks account for the difference. It takes longer to
boil and egg in Denver than it does in, say, LA.

If boiling point goes up with reduced atmospheric pressure, then why
does water boil as one approaches a vacuum at room temp?

Cooking time, not boiling point, goes up. How long would eggs take to cook
at room temperature?

Who said the boiling point goes up?? It takes longer to boil an egg in
Denver because the boiling point is _*LOWER*_ with lower atmospheric
pressure.
Click to expand...
Correct. It's also not good for tea too.


The "Boiling point" is the temperature at which the vapor pressure reaches
atmospheric pressure."
Click to expand...
Ever heard of "the Curate's egg" ?
http://en.wikipedia.org/wiki/Curate's_egg

Graham
 
Eeyore wrote:
Archimedes' Lever wrote:

Rich Grise <rich@example.net> wrote:
Eeyore wrote:
And that's normally good enough ! Best ignore the change in boiling point
vs atm pressure. ;~)
Best not - even cookbooks account for the difference. It takes longer to
boil and egg in Denver than it does in, say, LA.
If boiling point goes up with reduced atmospheric pressure, then why
does water boil as one approaches a vacuum at room temp?

I expect that's simply liberation of dissolved air.
Click to expand...
As Rich pointed out earlier, boiling occurs when the vapour pressure
equals the ambient pressure. The reason is that at that point there's
nothing to prevent bubbles from growing without limit. You do need to
nucleate the bubbles first, of course, which is why still liquids can be
superheated considerably before they launch.

Cheers,

Phil Hobbs
 
IanM wrote:

Spehro Pefhany wrote:
the renowned Eeyore wrote:
Don Bruder wrote:
Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:

I used to 'calibrate' thermocouples by putting them in boiling water.

100C/212F = nice cup of rolling-boil water at 1 standard atmosphere

Might not have been *PERFECT*, but it was at least reasonably close
enough for the stuff we were doing.

And that's normally good enough ! Best ignore the change in boiling point vs atm
pressure. ;~)

A bit of knowledge can be dangerous...

http://www.ucl.ac.uk/sts/chang/boiling/index.htm

Which is why I reccomended condensing steam on a metal block. Avoids
all sorts of problems with superheat. Once you've done that, might as
well use the same block in melting ice for consistancy.
Click to expand...
Sure, but my method works in the office kitchen with an electric kettle. Note that the
temp drops a couple of degrees when power is removed, indicating that the liberated
steam is (briefly) over 100C.

Graham
 
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