Ideas to get a controlled temperature of around -40C (also -40F) in a
test sample?

"Robustly" by physics:
100C - boiling water
0C - ice
-17C - brine-ice slurry (?)
??? -40C ???
-80C - "cardice" - solid CO2
-196C - liquid nitrogen

Reason is, found a way to tensile-test fillet welds, and so far always
seeing breaking strength come out at around 560MPa, when you do the
maths relating breaking force to the fracture area.

The 355MPa yield of the Rectangular Hollow Sections (RHS) isn't seen -
and I know they have exactly that yield stress from beam bending
measurements.

Here's the tests - "Alladin's Cave" of misdemeanours and skulduggery ?
;-)

http://www.weldsmith.co.uk/tech/struct/struct.html
"Steel Structural Performance index-page"

Various tests.

Specifically the fillet weld tensile tests

http://www.weldsmith.co.uk/tech/stru...4_fwbeamt.html
"Fillet welds tensile tested in beam test"

http://www.weldsmith.co.uk/tech/stru...t_testrig.html
"Tensile-test rig for beam-configuration fillet-weld samples"

Movie of - 10 seconds - shared on "Dropbox"
https://www.dropbox.com/s/esgwfk5jen..._fwtr.mp4?dl=0

Yup, I know that as a PhD level scientist I have to work as a welder
because everyone already ensconced in "office engineering" jobs
manicured in their white shirts sees me as a "Dennis Hopper like"
(think eg. "Blue Velvet" (1986) film) character of the science and
engineering world ;-)
If you keep the office door closed to all but your own manicured kind,
you can keep reality out. Who can blame them if no-one comes and
hurls them out into the cold hard world their scheme avoids? :-)

It would be helpful to see whether that "no yield event - straight to
local fracture at high(er) stress" is associated with a low
temperature brittleness charactistic.

I could "dam-off" the RHS close to the weld and at the far end, and
fill it with a cooling fluid.
Ice-brine looks good for -17C.

Throw a blanked over the entire sample for a while for all parts of
the sample to be at that temperature, then slide in the hydraulic
cylinder and "pump it up" and see what the temperature causes or does
not cause.

What about for -40C
???

Regards,
Rich Smith

"Richard Smith" wrote in message ...

Ideas to get a controlled temperature of around -40C (also -40F) in a
test sample?

The lowest setting on my Alpicool C20 DC-powered freezer is -40C. Temps
below -20C are accessed with the E1 special setting.
https://www.amazon.com/Alpicool-C20-.../dp/B075R1LH8D

It works well enough but isn't as rugged or hands-off reliable as a normal
AC-powered freezer, and really should have thicker insulation.

"Jim Wilkins" wrote in message ...

"Richard Smith" wrote in message ...

Ideas to get a controlled temperature of around -40C (also -40F) in a
test sample?

----------------------------
The lowest setting on my Alpicool C20 DC-powered freezer is -40C. Temps
below -20C are accessed with the E1 special setting.
https://www.amazon.com/Alpicool-C20-.../dp/B075R1LH8D

It works well enough but isn't as rugged or hands-off reliable as a normal
AC-powered freezer, and really should have thicker insulation.
------------------------------------------
I confirmed it could be set to -40C but didn't leave it there, as it's full
of food and would have taken a long time to settle.

My Alpi wouldn't quite cool to -20C in a hot car so I made an insulated
enclosure for it, 1" foam lined inside with a yoga mat to catch and drain
summer condensation. The exterior is thin birch plywood joined at the
corners with sheet metal angles inside and truss head screws. The lid is a
flap of Harbor Freight moving blanket, doubled.

On Thu, 04 Feb 2021 11:43:58 +0000, Richard Smith
wrote:

Ideas to get a controlled temperature of around -40C (also -40F) in a
test sample?

"Robustly" by physics:
100C - boiling water
0C - ice
-17C - brine-ice slurry (?)
??? -40C ???
-80C - "cardice" - solid CO2
-196C - liquid nitrogen

Reason is, found a way to tensile-test fillet welds, and so far always
seeing breaking strength come out at around 560MPa, when you do the
maths relating breaking force to the fracture area.

The 355MPa yield of the Rectangular Hollow Sections (RHS) isn't seen -
and I know they have exactly that yield stress from beam bending
measurements.

Here's the tests - "Alladin's Cave" of misdemeanours and skulduggery ?
;-)

http://www.weldsmith.co.uk/tech/struct/struct.html
"Steel Structural Performance index-page"

Various tests.

Specifically the fillet weld tensile tests

http://www.weldsmith.co.uk/tech/struct/201124_fwbeamt/201124_fwbeamt.html
"Fillet welds tensile tested in beam test"

http://www.weldsmith.co.uk/tech/struct/210122_fwtest_rig/210122_fwtest_testrig.html
"Tensile-test rig for beam-configuration fillet-weld samples"

Movie of - 10 seconds - shared on "Dropbox"
https://www.dropbox.com/s/esgwfk5jenhm024/210122_fwtr.mp4?dl=0

Yup, I know that as a PhD level scientist I have to work as a welder
because everyone already ensconced in "office engineering" jobs
manicured in their white shirts sees me as a "Dennis Hopper like"
(think eg. "Blue Velvet" (1986) film) character of the science and
engineering world ;-)
If you keep the office door closed to all but your own manicured kind,
you can keep reality out. Who can blame them if no-one comes and
hurls them out into the cold hard world their scheme avoids? :-)

It would be helpful to see whether that "no yield event - straight to
local fracture at high(er) stress" is associated with a low
temperature brittleness charactistic.

I could "dam-off" the RHS close to the weld and at the far end, and
fill it with a cooling fluid.
Ice-brine looks good for -17C.

Throw a blanked over the entire sample for a while for all parts of
the sample to be at that temperature, then slide in the hydraulic
cylinder and "pump it up" and see what the temperature causes or does
not cause.

What about for -40C
???

Propane boils at -42 C at atmospheric pressure.

Joe Gwinn

"Joe Gwinn" wrote in message
...

Propane boils at -42 C at atmospheric pressure.

Joe Gwinn

-------------------------------
I checked the weather on Spitzbergen to see if the experiment could be done
at ambient temperature there.
https://www.accuweather.com/en/sj/lo...orecast/310461

Funny, New England USA was that cold over the weekend, and we are at the
latitude of Spain.
https://brilliantmaps.com/cities-transposed-latitude/

"Jim Wilkins" writes:

"Joe Gwinn" wrote in message
...

Propane boils at -42 C at atmospheric pressure.

Joe Gwinn

-------------------------------
I checked the weather on Spitzbergen to see if the experiment could be
done at ambient temperature there.
https://www.accuweather.com/en/sj/lo...orecast/310461

Funny, New England USA was that cold over the weekend, and we are at
the latitude of Spain.
https://brilliantmaps.com/cities-transposed-latitude/

Spitzbergen idea - LOL !

On Friday, February 5, 2021 at 3:02:33 AM UTC-5, Richard Smith wrote:
"Jim Wilkins" writes:

"Joe Gwinn" wrote in message
...

Propane boils at -42 C at atmospheric pressure.

Joe Gwinn

-------------------------------
I checked the weather on Spitzbergen to see if the experiment could be
done at ambient temperature there.
https://www.accuweather.com/en/sj/lo...orecast/310461

Funny, New England USA was that cold over the weekend, and we are at
the latitude of Spain.
https://brilliantmaps.com/cities-transposed-latitude/

That must mean that the tip end of Narragansett is about the same average temperature as the well known shores of Spain in the summer time.

Spitzbergen idea - LOL !

Wow, images of Spitzbergen are nice. I get words like Spitzbergen and Zugspitze (the highest mountain in German, literally translated as "train peak") mixed up.

"Transition Zone" wrote in message
...

On Friday, February 5, 2021 at 3:02:33 AM UTC-5, Richard Smith wrote:
"Jim Wilkins" writes:

"Joe Gwinn" wrote in message
...

Propane boils at -42 C at atmospheric pressure.

Joe Gwinn

-------------------------------
I checked the weather on Spitzbergen to see if the experiment could be
done at ambient temperature there.
https://www.accuweather.com/en/sj/lo...orecast/310461

Funny, New England USA was that cold over the weekend, and we are at
the latitude of Spain.
https://brilliantmaps.com/cities-transposed-latitude/

That must mean that the tip end of Narragansett is about the same average
temperature as the well known shores of Spain in the summer time.

Spitzbergen idea - LOL !

Wow, images of Spitzbergen are nice. I get words like Spitzbergen and
Zugspitze (the highest mountain in German, literally translated as "train
peak") mixed up.

----------------
Away from the coast the summertime highs here are quite close to Madrid's,
35C and above.

I rode the cable car up the Zugspitze and yes, it's spectacular.

My best memory of European mountains was flying low over the lesser-known
Swabian Jura (Alps) between Stuttgart and Augsburg in an Army helicopter
with a view straight down. Probably the worst was riding a speeding, tilting
van up the winding road to Hohenzollern castle and feeling like we were
about to fly off the road and tumble down the steep slope.

Emperor Frederick the Great was there, in a plain wooden coffin on sawhorses
in the castle's entrance.

Joe Gwinn writes:

On Thu, 04 Feb 2021 11:43:58 +0000, Richard Smith
wrote:

Ideas to get a controlled temperature of around -40C (also -40F) in a
test sample?

"Robustly" by physics:
100C - boiling water
0C - ice
-17C - brine-ice slurry (?)
??? -40C ???
-80C - "cardice" - solid CO2
-196C - liquid nitrogen

Reason is, found a way to tensile-test fillet welds, and so far always
seeing breaking strength come out at around 560MPa, when you do the
maths relating breaking force to the fracture area.

The 355MPa yield of the Rectangular Hollow Sections (RHS) isn't seen -
and I know they have exactly that yield stress from beam bending
measurements.

Here's the tests - "Alladin's Cave" of misdemeanours and skulduggery ?
;-)

http://www.weldsmith.co.uk/tech/struct/struct.html
"Steel Structural Performance index-page"

Various tests.

Specifically the fillet weld tensile tests

http://www.weldsmith.co.uk/tech/struct/201124_fwbeamt/201124_fwbeamt.html
"Fillet welds tensile tested in beam test"

http://www.weldsmith.co.uk/tech/struct/210122_fwtest_rig/210122_fwtest_testrig.html
"Tensile-test rig for beam-configuration fillet-weld samples"

Movie of - 10 seconds - shared on "Dropbox"
https://www.dropbox.com/s/esgwfk5jenhm024/210122_fwtr.mp4?dl=0

Yup, I know that as a PhD level scientist I have to work as a welder
because everyone already ensconced in "office engineering" jobs
manicured in their white shirts sees me as a "Dennis Hopper like"
(think eg. "Blue Velvet" (1986) film) character of the science and
engineering world ;-)
If you keep the office door closed to all but your own manicured kind,
you can keep reality out. Who can blame them if no-one comes and
hurls them out into the cold hard world their scheme avoids? :-)

It would be helpful to see whether that "no yield event - straight to
local fracture at high(er) stress" is associated with a low
temperature brittleness charactistic.

I could "dam-off" the RHS close to the weld and at the far end, and
fill it with a cooling fluid.
Ice-brine looks good for -17C.

Throw a blanked over the entire sample for a while for all parts of
the sample to be at that temperature, then slide in the hydraulic
cylinder and "pump it up" and see what the temperature causes or does
not cause.

What about for -40C
???

Propane boils at -42 C at atmospheric pressure.

Joe Gwinn

Thanks for suggestion. Well rooted in science.
I fear that as the sample gets colder with propane evaporation, we
could get a hair-trim if the evaporated gas ignites.

The sample halves hurl around on sample weld breaking, so putting on a
"vent tube" with the propane burning at the outlet - a "flare" -
doesn't seem a viable solution.

It might be that I have to do something with "cardice" - solid CO2.
Throw-in bits until reaches -40C.

Or cool to lower temperature and pump the cylinder when weld area has is
showing -40C by thermocouple.

Thanks for suggestions.

I just looked online and find
https://en.wikipedia.org/wiki/Brine
that lowest melting point is -21.1C

Something you learn about experimenting - while you do make sure
everything holds together as it should, you don't look for the n-th
degree of accuracy of physical conditions in the proof-of-concept
tries.

To think in planning that a particular exact temperature is important
is the error of thinking that if you specify something enough, "God"
has to conform. Not going to happen. Get a pretty cold temperature
and observe what is there to observe.

Regards,

"Richard Smith" wrote in message ...
....
Or cool to lower temperature and pump the cylinder when weld area has is
showing -40C by thermocouple.

-------------------

That's the first method I would try, to check your assumptions and procedure
and shrapnel containment.

This suggests that impurity levels might be a significant uncontrolled
variable in your experiments:
https://www.tf.uni-kiel.de/matwis/am...tr/s9_1_1.html

Is -40C the lowest you expect in European service?
https://en.wikipedia.org/wiki/Operating_temperature

Some industrial temperature controllers have a cooling option that can
operate a solenoid valve to regulate the temperature with evaporating CO2
from a tank of room-temperature liquid.
https://www.linde-gas.com/en/process...ing/index.html
"Liquid carbon dioxide converts to solid carbon dioxide snow at €“79ºC
(€“109ºF)."

If the test chamber is nearly sealed the escaping gas should reduce or
prevent frost covering the sample. US regulations required an oxygen level
sensor and alarm at the test station. The body's breathing mechanism
responds to CO2 level (pH) in the blood, not oxygen level, so you may not
realize you are about to pass out from anoxia, especially with liquid
nitrogen.

On 2/5/21 3:28 AM, Richard Smith wrote:
Joe Gwinn writes:

On Thu, 04 Feb 2021 11:43:58 +0000, Richard Smith
wrote:

Ideas to get a controlled temperature of around -40C (also -40F) in a
test sample?

"Robustly" by physics:
100C - boiling water
0C - ice
-17C - brine-ice slurry (?)
??? -40C ???
-80C - "cardice" - solid CO2
-196C - liquid nitrogen

Reason is, found a way to tensile-test fillet welds, and so far always
seeing breaking strength come out at around 560MPa, when you do the
maths relating breaking force to the fracture area.

The 355MPa yield of the Rectangular Hollow Sections (RHS) isn't seen -
and I know they have exactly that yield stress from beam bending
measurements.

Here's the tests - "Alladin's Cave" of misdemeanours and skulduggery ?
;-)

http://www.weldsmith.co.uk/tech/struct/struct.html
"Steel Structural Performance index-page"

Various tests.

Specifically the fillet weld tensile tests

http://www.weldsmith.co.uk/tech/struct/201124_fwbeamt/201124_fwbeamt.html
"Fillet welds tensile tested in beam test"

http://www.weldsmith.co.uk/tech/struct/210122_fwtest_rig/210122_fwtest_testrig.html
"Tensile-test rig for beam-configuration fillet-weld samples"

Movie of - 10 seconds - shared on "Dropbox"
https://www.dropbox.com/s/esgwfk5jenhm024/210122_fwtr.mp4?dl=0

Yup, I know that as a PhD level scientist I have to work as a welder
because everyone already ensconced in "office engineering" jobs
manicured in their white shirts sees me as a "Dennis Hopper like"
(think eg. "Blue Velvet" (1986) film) character of the science and
engineering world ;-)
If you keep the office door closed to all but your own manicured kind,
you can keep reality out. Who can blame them if no-one comes and
hurls them out into the cold hard world their scheme avoids? :-)

It would be helpful to see whether that "no yield event - straight to
local fracture at high(er) stress" is associated with a low
temperature brittleness charactistic.

I could "dam-off" the RHS close to the weld and at the far end, and
fill it with a cooling fluid.
Ice-brine looks good for -17C.

Throw a blanked over the entire sample for a while for all parts of
the sample to be at that temperature, then slide in the hydraulic
cylinder and "pump it up" and see what the temperature causes or does
not cause.

What about for -40C
???

Propane boils at -42 C at atmospheric pressure.

Joe Gwinn

Thanks for suggestion. Well rooted in science.
I fear that as the sample gets colder with propane evaporation, we
could get a hair-trim if the evaporated gas ignites.

The sample halves hurl around on sample weld breaking, so putting on a
"vent tube" with the propane burning at the outlet - a "flare" -
doesn't seem a viable solution.

It might be that I have to do something with "cardice" - solid CO2.
Throw-in bits until reaches -40C.

Or cool to lower temperature and pump the cylinder when weld area has is
showing -40C by thermocouple.

Thanks for suggestions.

I just looked online and find
https://en.wikipedia.org/wiki/Brine
that lowest melting point is -21.1C

Something you learn about experimenting - while you do make sure
everything holds together as it should, you don't look for the n-th
degree of accuracy of physical conditions in the proof-of-concept
tries.

To think in planning that a particular exact temperature is important
is the error of thinking that if you specify something enough, "God"
has to conform. Not going to happen. Get a pretty cold temperature
and observe what is there to observe.

There are lots of other things besides sodium chloride to make "salt"
baths from :-). See https://en.wikipedia.org/wiki/List_of_cooling_baths
for one list, and look at reference 2 and the reference pdf in ref 2
(https://www.larkinweb.co.uk/science/...ng%20baths.pdf) for
a bit more info. I'd try calcium chloride hexahydrate/water either at
the ratio for -41C or a bit stronger since they say it is difficult to
reach the listed temps. You could also precool your metal with dry ice
and even add some dry ice to the salt bath while it is cooling down, or
put the salt bath in a small tub in a larger tub with dry ice packed
around it. I'd make the starting ice either from distilled water (cheap
at grocery stores) or reverse osmosis water if you have a home system
already. If having the metal dripping with wet calcium chloride is a
problem during your test put the piece in a ziploc bag. Partially seal
the bag so about an inch at one side is still open then slowly submerge
the bag in plain water while holding that corner out of the water. The
air will be forced out so you get good contact between bag and metal for
good heat transfer. Finish sealing the bag when as much of the air as
possible is removed. Just pretend it is a steak you are about to cook
sous vide :-).

--
Regards,
Carl

Carl writes:

... ... ...


There are lots of other things besides sodium chloride to make "salt"
baths from :-). See
https://en.wikipedia.org/wiki/List_of_cooling_baths for one list, and
look at reference 2 and the reference pdf in ref 2
(https://www.larkinweb.co.uk/science/...ng%20baths.pdf)
for a bit more info. I'd try calcium chloride hexahydrate/water
either at the ratio for -41C or a bit stronger since they say it is
difficult to reach the listed temps. You could also precool your
metal with dry ice and even add some dry ice to the salt bath while it
is cooling down, or put the salt bath in a small tub in a larger tub
with dry ice packed around it. I'd make the starting ice either from
distilled water (cheap at grocery stores) or reverse osmosis water if
you have a home system already. If having the metal dripping with wet
calcium chloride is a problem during your test put the piece in a
ziploc bag. Partially seal the bag so about an inch at one side is
still open then slowly submerge the bag in plain water while holding
that corner out of the water. The air will be forced out so you get
good contact between bag and metal for good heat transfer. Finish
sealing the bag when as much of the air as possible is removed. Just
pretend it is a steak you are about to cook sous vide :-).

--
Regards,
Carl

Stunningly good info. Thanks.

I could see what NaCl-brine-ice does for the test, knowing there's
further I could go.

Dam the ends of the Rectangular Hollow Sections to hold the brine-ice
internally = direct contact. Contained. Salt on the sample wouldn't
matter anyway.

Many thanks again.

"Richard Smith" wrote in message ...

I could see what NaCl-brine-ice does for the test, knowing there's
further I could go.

---------------------------------

During a winter power outage I found that a mix of snow and road salt (NaCl
+ ?) fell to 5F, -15C.

On Fri, 05 Feb 2021 08:28:07 +0000, Richard Smith
wrote:

Joe Gwinn writes:

On Thu, 04 Feb 2021 11:43:58 +0000, Richard Smith
wrote:

Ideas to get a controlled temperature of around -40C (also -40F) in a
test sample?

"Robustly" by physics:
100C - boiling water
0C - ice
-17C - brine-ice slurry (?)
??? -40C ???
-80C - "cardice" - solid CO2
-196C - liquid nitrogen

Reason is, found a way to tensile-test fillet welds, and so far always
seeing breaking strength come out at around 560MPa, when you do the
maths relating breaking force to the fracture area.

The 355MPa yield of the Rectangular Hollow Sections (RHS) isn't seen -
and I know they have exactly that yield stress from beam bending
measurements.

Here's the tests - "Alladin's Cave" of misdemeanours and skulduggery ?
;-)

http://www.weldsmith.co.uk/tech/struct/struct.html
"Steel Structural Performance index-page"

Various tests.

Specifically the fillet weld tensile tests

http://www.weldsmith.co.uk/tech/struct/201124_fwbeamt/201124_fwbeamt.html
"Fillet welds tensile tested in beam test"

http://www.weldsmith.co.uk/tech/struct/210122_fwtest_rig/210122_fwtest_testrig.html
"Tensile-test rig for beam-configuration fillet-weld samples"

Movie of - 10 seconds - shared on "Dropbox"
https://www.dropbox.com/s/esgwfk5jenhm024/210122_fwtr.mp4?dl=0

Yup, I know that as a PhD level scientist I have to work as a welder
because everyone already ensconced in "office engineering" jobs
manicured in their white shirts sees me as a "Dennis Hopper like"
(think eg. "Blue Velvet" (1986) film) character of the science and
engineering world ;-)
If you keep the office door closed to all but your own manicured kind,
you can keep reality out. Who can blame them if no-one comes and
hurls them out into the cold hard world their scheme avoids? :-)

It would be helpful to see whether that "no yield event - straight to
local fracture at high(er) stress" is associated with a low
temperature brittleness charactistic.

I could "dam-off" the RHS close to the weld and at the far end, and
fill it with a cooling fluid.
Ice-brine looks good for -17C.

Throw a blanked over the entire sample for a while for all parts of
the sample to be at that temperature, then slide in the hydraulic
cylinder and "pump it up" and see what the temperature causes or does
not cause.

What about for -40C
???

Propane boils at -42 C at atmospheric pressure.

Joe Gwinn

Thanks for suggestion. Well rooted in science.
I fear that as the sample gets colder with propane evaporation, we
could get a hair-trim if the evaporated gas ignites.

The sample halves hurl around on sample weld breaking, so putting on a
"vent tube" with the propane burning at the outlet - a "flare" -
doesn't seem a viable solution.

It might be that I have to do something with "cardice" - solid CO2.
Throw-in bits until reaches -40C.

Or cool to lower temperature and pump the cylinder when weld area has is
showing -40C by thermocouple.

Thanks for suggestions.

One dodge is to make a heat pipe using propane as the working fluid,
dry ice as the coolant.

Have liquid propane in the sealed copper boiler with a tube going
uphill to a copper condenser cooled by dry ice in alcohol. The dry
ice boils at -109 C, well above the freezing point of propane, so what
will happen is that the propane will boil at -42 C, with the vapor
rising to the condenser, where the propane will liquefy, and run back
down to the boiler. This process is self-regulating so long as things
are well insulated. But do this outside, and a 2-meter flare tube is
a good idea.

The copper stuff can be ordinary plumbing tubing and fixtures. For a
one-off, plumbers solder is good enough. For a true seal, braze with
phosphorus-copper brazing filler, as used for HVAC systems.

Joe Gwinn

"Joe Gwinn" wrote in message
...
....
Have liquid propane in the sealed copper boiler with a tube going
uphill to a copper condenser cooled by dry ice in alcohol.
....
The copper stuff can be ordinary plumbing tubing and fixtures. For a
one-off, plumbers solder is good enough. For a true seal, braze with
phosphorus-copper brazing filler, as used for HVAC systems.
....
Joe Gwinn

---------------------

The pipe fitting that enables making a condenser or similar concentric tube
structure is a pipe reducer with the smaller end bored through on a lathe.
Brass is easier than copper to chuck and turn. A 6-jaw chuck helps hold the
reducer without (much) distortion, or you can jam a fitted wood plug into
the large end.

When I learned industrial refrigeration in the 1970's this is what we brazed
joints with:
https://www.amazon.com/Lucas-Milhaup.../dp/B06Y1N5517

On Fri, 5 Feb 2021 17:40:49 -0500, "Jim Wilkins"
wrote:

"Joe Gwinn" wrote in message
.. .
...
Have liquid propane in the sealed copper boiler with a tube going
uphill to a copper condenser cooled by dry ice in alcohol.
...
The copper stuff can be ordinary plumbing tubing and fixtures. For a
one-off, plumbers solder is good enough. For a true seal, braze with
phosphorus-copper brazing filler, as used for HVAC systems.
...
Joe Gwinn

---------------------

The pipe fitting that enables making a condenser or similar concentric tube
structure is a pipe reducer with the smaller end bored through on a lathe.
Brass is easier than copper to chuck and turn. A 6-jaw chuck helps hold the
reducer without (much) distortion, or you can jam a fitted wood plug into
the large end.

I don't visualize this.

What I was thinking was a simple one-pipe system, with vapor going up
and condensate running down. The propane inventory need not be large.


When I learned industrial refrigeration in the 1970's this is what we brazed
joints with:
https://www.amazon.com/Lucas-Milhaupt-95150-Sil-Fos-Brazing-Alloy/dp/B06Y1N5517

Yeah, that's the stuff.

If you braze all the joints, you can hermetically seal the propane
inside the heat pipe. Make sure that the total volume is large enough
to prevent overpressure damage at room temperature. Or provide a
pressure releas valve and refill before each use.

Joe Gwinn

"Richard Smith" wrote in message ...

......
Yup, I know that as a PhD level scientist I have to work as a welder
because everyone already ensconced in "office engineering" jobs
manicured in their white shirts sees me as a "Dennis Hopper like"
(think eg. "Blue Velvet" (1986) film) character of the science and
engineering world ;-)
If you keep the office door closed to all but your own manicured kind,
you can keep reality out. Who can blame them if no-one comes and
hurls them out into the cold hard world their scheme avoids? :-)

Rich Smith
--------------------------------

The snobbery of "Two Cultures" exists in the US scientific community too. I
first encountered it as a Chemistry undergrad, from professors who either
worked with government and industry or shunned all but pure academic
research, and tried to convince us theirs was the only ethical path.

As a lab manager in a government research facility I worked with both
hands-on and hands-off engineers, and again the theoretical, hands-off ones
could be somewhat intolerant of people who could be both. I also saw that in
Mensa, mainly from mathematicians. It was fun to watch the confusion after
someone who had binned me as a mere craftsman found I could and solve
engineering math problems mentally faster than they could with a calculator.

Personally I've been glad to stay in the lab, designing and building
hardware, and avoid boring meetings and report writing. Another lab tech
made a bumper sticker "Techs can do what engineers only dream of".

Not all great theoreticians kept their hands clean:
https://www.fromthegrapevine.com/inn...ator-invention

"Jim Wilkins" writes:

"Richard Smith" wrote in message ...

.....
Yup, I know that as a PhD level scientist I have to work as a welder
...
Rich Smith
--------------------------------

...
tech made a bumper sticker "Techs can do what engineers only dream
of".
...

LOL ;-)

On Fri, 05 Feb 2021 08:36:21 +0000, Richard Smith
wrote:

"Jim Wilkins" writes:

"Richard Smith" wrote in message ...

.....
Yup, I know that as a PhD level scientist I have to work as a welder
...
Rich Smith
--------------------------------

...
tech made a bumper sticker "Techs can do what engineers only dream
of".
...

LOL ;-)
"Techs keep Engineers out of trouble!"