Re: Helium [was: t-bird screwing up]
On 11/2/22 01:07, David Wright wrote:
On Tue 01 Nov 2022 at 06:49:09 (+0100), tomas@tuxteam.de wrote:
On Mon, Oct 31, 2022 at 06:32:17PM -0400, gene heskett wrote:
[...]
I think, but don't know for sure, that they were also helium filled drives,
a guaranteed disaster.
They used the helium to make the heads fly lower, and when the helium leaked
out, and air leaked in,
Possible.
the heads flew too high to read the disk. I don't know where Seagate
recruited the engineers who thought
up that idea,
Whatever, even I with an 8th grade diploma, knows you cannot keep helium
anyplace for very long. Put it in a monel metal
bottle with walls an inch thick and its molecules's are so small that 10% of
it is gone in 6 or 7 hours.
So the He cylinders that we used after a few months in storage
really contained nothing at all!
We had such large bottles at Stellardyne Labs, in Sandy Eggo in the
early 1960 time frame, used to test the
ullage pressure regulators that kept the Atlas from collapsing under its
own weight when it was fully fueled
and ready to give John Glenn his first orbital ride. The procedure for
the end of the night shift was to pump
it all into this bank of bottles with a huge cardox 6 stage compressor
in the back yard, putting them at around
7200 psi. All recorded in an electronic log on rolls of graphic printer
paper.
These bottles had monel walls about 2" thick, 10 feet tall, a dozen of
them. Pipes to/from were about 3" in
diameter, monel with a 1" bore.
8 hours later when the day shift clocked in, those bottles were down to
5800 lbs. That place used 95% of the
US production of Helium at the time, with a new truckload at about $100k
worth of helium nominally 2 x a
week to keep it operational.
I ran the recorders that logged the tests on those pressure regulators
for several months. I was that same year,
a bench tech at Oceanographic Engineering with a backyard dock right on
the bay, building the tv cameras that
were on the navy's Trieste submersible when it went to the bottom of the
mohole. So my fingerprints were all
over those 2 cameras which worked well at 18,000 psi 37k feet down . So
I have been there, and done that in
what most would call pretty exotic places.
I spent the last 18+ years of my working life keeping the local CBS
affiliate on the air, without help other than
min wage tx operators about 80% of that time. The only stuff that got
shipped to the factory when it broke was
stuff they didn't supply manual's on for proprietary reasons. I did all
the rest. The work was fun, sometimes the
people weren't. One girl who was legendarily hard on news cameras was
eventually fired, but I wasn't fire-able.
And I have been accused of walking on electronic water several times. To
me, its a chuckle, goes with the territory.
And these
jerks thought they could seal it up in a drive housing 1/16" thick?
The operative word is seal, not the thickness of the monel walls.
Seal—and no cracks.
You still don't get it, the helium molecule is so small it wiggles thru
a steel walls huge molecules
like they were a layer of felt. Monel alloy is denser but it still leaks.
This is only a half-truth. You know what goes out faster than helium?
Vacuum. And there was a whole glorious epoch in electronics which did
rely on keeping vacuum "in". You should have some fond memories of
that.
I do, and there are still places where a vacuum tube is still the best
way to do the job.
To be fair, most vacuum tubes aren't bathed in helium, but air, and
then only at a one atmosphere differential pressure. A gas cylinder
might be as high as 500 atmospheres.
And vacuum tubes do contain a getter to deal with outgassing, which
will help mitigate slight leaks.
Or, in the case of a high power beam tube such as the now old technology
klystron, where
the magnetically focused electron beam catches and carries the
occasional gas molecule,
and carries it to the collector bucket, a huge copper funnel with at
least 70 gallons of pure
water a minute to cool it, the gas hitting the copper so hard its buried
and takes weeks to
escape back into the vacuum. They were very expensive, and I have tested
more than one
and found it gassy but as long as it didn't arc-over, I could apply the
beam power slowly and
watch the body current fall over the next few hours until it was making
90% power out of a
tube a station in New Orleans had starved for coolant and burnt the
paint off the collector bucket,
and sold it to us for 10k$. All while 4 state engineers with EE's on
the wall were claiming
it wouldn't work as it was bent in shipment from bad repacking. I simply
bent the magnetic
field to match.
To me, they didn't understand the physics involved including E=M*C*C, I
did and do.
They should have sued the school that issued that EE for a tuition
refund for not
teaching them right. Einsteins theory ought to be the first thing they
teach, not skipped,
Its effects on the transit time of any vacuum tube should NOT be a
puzzle by the time they've
a diploma to hang on the wall. My diploma isn't an EE, but a CET. And it
has got me every job I've
applied for since 1972. I saw the announcement of the final test in the
paper, walked in the door
with my $20 to sit for the test, made 2 trips to the john as I was down
with that seasons flu, and
still handed the test papers back to the prof, with an expected 4 hours
to do it, in 45 minutes.
Multiple choice, the prof laid the answer stencil on it and saw a sea of
black he hadn't seen in 5
years of teaching that course, I was the first to pass that test. I
didn't say it, but he was in way over
his head, trying to teach the subject.
Cheers,
David.
Take care and stay well, David.
Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/>
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