Oven thermal insulation
Hi Randy,
80°C and 'highest stability' is simply a contradiction in itself.
Therefore, if you really go for highest stability, please run your
voltage reference at < 60°C only, best would be 45°C!
In this case, ordinary styrofoam is suitable, higher temperatures
require poly sulfone, like used on the HP3458A reference board, or the
VALOX(TM) plastic which is used for the LM399.
Frank
Frank,
I don't plan on operating at 80C. I just want an insulation that can
withstand up to 80C so i have a safety margin. 45C is probably too low for
my environment but 50C might be doable.
Thanks,
Randy
On Tue, Jul 7, 2015 at 12:29 AM, Frank Stellmach <frank.stellmach@freenet.de
wrote:
Hi Randy,
80°C and 'highest stability' is simply a contradiction in itself.
Therefore, if you really go for highest stability, please run your voltage
reference at < 60°C only, best would be 45°C!
In this case, ordinary styrofoam is suitable, higher temperatures require
poly sulfone, like used on the HP3458A reference board, or the VALOX(TM)
plastic which is used for the LM399.
Frank
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Bear in mind that the common ordinary styrofoam cup
does just fine when containing boiling water.
Where it has problems is when it is in contact with
the heating elements, and they are allowed to overshoot
the desired temperature greatly.
The answer is to make sure that your heating element is
in good thermal contact with the metal oven, and not in
contact with your insulation... That, and don't get too
aggressive with the delta t component of your PID algorithm.
-Chuck Harris
Randy Evans wrote:
Frank,
I don't plan on operating at 80C. I just want an insulation that can
withstand up to 80C so i have a safety margin. 45C is probably too low for
my environment but 50C might be doable.
Thanks,
Randy
On Tue, Jul 7, 2015 at 12:29 AM, Frank Stellmach <frank.stellmach@freenet.de
wrote:
Hi Randy,
80°C and 'highest stability' is simply a contradiction in itself.
Therefore, if you really go for highest stability, please run your voltage
reference at < 60°C only, best would be 45°C!
In this case, ordinary styrofoam is suitable, higher temperatures require
poly sulfone, like used on the HP3458A reference board, or the VALOX(TM)
plastic which is used for the LM399.
Frank
I bought a couple of the sample sheets of Spaceloft Areogel (Ebay #
171328843398) a couple monthas ago. Cheap enough at $7.99 for a 10x14 piece
with free shipping. It's 5mm thick, and easily cut with scissors.
The datasheet that was supplied with the samples say that its max
temperature is 200°C, so will surely work in a 45°C oven. R-Value is
advertised to be 10.3 per inch.
I bought it in anticipation of building an oven for a voltage reference, as
you are. I'm still considering the size & shape of the box for the oven.
Other irons in the fire presently, so not on my front burner.
It certainly is a better insulator than fiberglass or Great Stuff foam. I
find it rather suspicious that the R-value of Great Stuff doesn't appear in
any of the ads, brochures or data sheets. I think its value is more in
favor of its use as a sealant trather than as insulation.
Cheers,
Dave M
Randy Evans wrote:
Frank,
I don't plan on operating at 80C. I just want an insulation that can
withstand up to 80C so i have a safety margin. 45C is probably too
low for my environment but 50C might be doable.
Thanks,
Randy
On Tue, Jul 7, 2015 at 12:29 AM, Frank Stellmach
<frank.stellmach@freenet.de
wrote:
Hi Randy,
80°C and 'highest stability' is simply a contradiction in itself.
Therefore, if you really go for highest stability, please run your
voltage reference at < 60°C only, best would be 45°C!
In this case, ordinary styrofoam is suitable, higher temperatures
require poly sulfone, like used on the HP3458A reference board, or
the VALOX(TM) plastic which is used for the LM399.
Frank
Chuck wrote:
Bear in mind that the common ordinary styrofoam
cup does just fine when containing boiling water.
Sure, for the 4-5 minutes the water stays above 70C. But over 5-10
years 24/7/365....
I once broke my office coffee cup and temporarily used a styrofoam
cup as a replacement. I brewed tea in it once or twice a day, and in
just a few weeks it had gone through significant dimensional changes
(it was a little smaller and somewhat irregularly shaped).
Best regards,
Charles
Hi:
Look at cork.
Mail_Attachment --
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html
Charles Steinmetz wrote:
Chuck wrote:
Bear in mind that the common ordinary styrofoam
cup does just fine when containing boiling water.
Sure, for the 4-5 minutes the water stays above 70C. But over 5-10 years 24/7/365....
I once broke my office coffee cup and temporarily used a styrofoam cup as a replacement. I brewed tea in it once or
twice a day, and in just a few weeks it had gone through significant dimensional changes (it was a little smaller and
somewhat irregularly shaped).
Best regards,
Charles
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