Vario flask insulation

No. The copper (they should be copper not some other metal) pot scourers
are there as a heat sink, nothing to do with volume.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Andy Durbin" wrote in message
om...


Chris Nicholas wrote in message
...

All the installations I have seen use a standard vacuum flask with no
additional insulation, but they were all buried either beneath/behind
the instrument panel, or inside the fuselage - anyway in shadow.

A key element I have read about, and all mine have been fitted with, is
copper pan scourers loosely filling the interior of the flask, so that
temperature variation within the capacity is eliminated.

However, I am no expert, and I look forward to some who are telling how
it really should be done.

Chris N.


I thought the pot scrubbers were used to reduce the flask capacity to
compensate for the capacity added by a long tubing run.

Andy.

Chris Nicholas wrote in message ...
All the installations I have seen use a standard vacuum flask with no
additional insulation, but they were all buried either beneath/behind
the instrument panel, or inside the fuselage - anyway in shadow.

A key element I have read about, and all mine have been fitted with, is
copper pan scourers loosely filling the interior of the flask, so that
temperature variation within the capacity is elinimated.

It's interesting to note that these two measures have very different
effects. The insulation ensures adiabatic expansion, which means that
the temperature of the air drops as the pressure falls. The copper is
there to make sure that the temperature stays the same.

Isn't thermodynamics fun?

Ian

At 14:00 13 January 2004, Andy Durbin wrote:

I thought the pot scrubbers were used to reduce the
flask capacity to
compensate for the capacity added by a long tubing
run.

Andy

Andy,

You can fill a pint beer glass with water to the brim
and then slowly introduce a fine pot scrubber wihout
spilling a drop if you are careful. I can't remember
where I first heard that but I didn't believe it until
I tried it.

John Galloway

Michael McNulty wrote in message news:DCLMb.408$
A vacuum

Awwww. you cheated, that's not a 'material'....isn't a vacuum a lack
of material?? ;-)

At 14:36 13 January 2004, Bob Lepp wrote:
Michael McNulty wrote in message news: A vacuum

Awwww. you cheated, that's not a 'material'....isn't
a vacuum a lack
of material?? ;-)


That what makes it so good! No material to conduct
heat!')

Cliff

"Todd Pattist" wrote in message . They'll
corrode and put junk into the Bohli.

Snip-----

2) I had to disconnect the Bohli from the TE probe as it
interfered with my older Ilec system which uses a small
internal capacity. It wasn't the Bohli's fault, but the
large capacity on the mechanical and the small capacity on
the electric produced capacity to capacity crossflow that
interfered with the Ilec.
Todd Pattist - "WH" Ventus C

Yeah, I've been thinking of this possibility if I ever want to add something
like the Ilec. I plan to recondition the Bohli compensation diaphragm with
new o-rings and store it carefully so that it can be converted back to
pitot/static connections if the need arises.

Bill Daniels

Everyone is talking about copper insulation inside the vario capacity
bottle but two years ago a German made bottle installed in my PW6 had
steel material -- the compass went nuts. The bottle had to be sent back
for demagnetizing !!

Todd Pattist wrote:
"Bill Daniels" wrote:


I'm fiddling with a Bohli Variometer that originally had a TE compensation
diaphragm that connected to the pitot. (A Bohli uses the same taut band
technology as the Sage except it's shorter and the needle is at the face of
the instrument.)


I've got a Bohli - it's a nice vario. You've got lots of
answers to your insulation question, so I'll just add this -

1) When you add the copper scrubbers to your capacity (good
idea), first pull off any metal buttons on the top of the
scrubbers. They'll corrode and put junk into the Bohli.

2) I had to disconnect the Bohli from the TE probe as it
interfered with my older Ilec system which uses a small
internal capacity. It wasn't the Bohli's fault, but the
large capacity on the mechanical and the small capacity on
the electric produced capacity to capacity crossflow that
interfered with the Ilec.
Todd Pattist - "WH" Ventus C
(Remove DONTSPAMME from address to email reply.)

You can fill a pint beer glass with water to the brim
and then slowly introduce a fine pot scrubber wihout
spilling a drop if you are careful. I can't remember
where I first heard that but I didn't believe it until
I tried it.

John Galloway

What a waste of beer! Hopefully the scrubber didn't have any soap or
detergent? 8-)

Keith

John Galloway wrote in message ...
At 14:00 13 January 2004, Andy Durbin wrote:

I thought the pot scrubbers were used to reduce the
flask capacity to
compensate for the capacity added by a long tubing
run.

Andy

Andy,

You can fill a pint beer glass with water to the brim
and then slowly introduce a fine pot scrubber wihout
spilling a drop if you are careful. I can't remember
where I first heard that but I didn't believe it until
I tried it.

John Galloway

That seems to say that the volume of copper is *very* small so its
mass would be too. Is there any useful heat exchange between a
negligible mass of copper and .45 litres of air?

I'll add the knowledge to my useful pub tricks list though.

Andy

At 15:54 13 January 2004, Keith W wrote:

You can fill a pint beer glass with water to the brim
and then slowly introduce a fine pot scrubber wihout
spilling a drop if you are careful. I can't remember
where I first heard that but I didn't believe it until
I tried it.

John Galloway

What a waste of beer! Hopefully the scrubber didn't
have any soap or
detergent? 8-)

Keith

Keith,

I may be daft but not that daft as another read will
confirm:-)

John