h a l f b a k e r yThink of it as a spell checker that insults you, as well.
add, search, annotate, link, view, overview, recent, by name, random
news, help, about, links, report a problem
browse anonymously,
or get an account
and write.
register,
|
|
|
Please log in.
Before you can vote, you need to register.
Please log in or create an account.
|
During the recent events, a remarkable amount of
equipment has failed. I understand how some devices, cars
for example, respond badly to disuse. Things like oil seals
dry out and let in air/water vapor etc. But while being
completely undisturbed, my lab has had 2 computers and 2
freezers fail
catastrophically. Computers are trivial to
replace, they can often be found lying around in other labs
for example, but laboratory freezers often contain things
of a totally irreplaceable nature. A single DNA plasmid that
took a dedicated scientist 3 months to create? We have
>1000 of them. Tissue samples from the only known human
family to have mutations in a certain protein? Just the
permission paperwork and organization of doctors/patients
on the other side of the world through 2 languages &
multiple customs inspections remaining carefully frozen is
a feat. Replacing them? Well, they're all dead, it's an
important protein. Anyhow, let's take a look at how this
problem is normally solved.
So, a lab grade -80C freezer is a hefty beast with a price
tag roughly the same as a Ferrari with similar running costs
and none of the glamour. Because they may contain
valuable or dangerous substances, they usually come with
an alarm system. This usually consists of a lead-acid
battery in the bottom that powers the electronics in the
event of a power failure etc. In our case, the electronics
sense rising temperature and trigger a relay. This relay is
wired into a whole-building alarm system that alerts a
dedicated team of staff who has a list of contacts for each
freezer.
This system failed. For several reasons. In one case, the
alarm triggered the relay did it's thing, the alert went to
the building system and... the dedicated staff retired last
June. In another case, a purchase order for a new battery
was placed only to be cancelled by a senior administrator*
because: "freezers running on batteries, I wasn't born
yesterday!"
So, maybe it is dumb to rely on a 12V lead acid battery
that is doomed to fail. They should be replaced on a
schedule, but science grants are costed to the penny on
exciting sciencey stuff and noone ever got money for
maintenance, calibration, cleaning, or... events. A walk
around the floor revealed 6/28 -80C freezers with battery
warning lights on. Clearly a widespread problem. A more
permanent solution would be useful, so what do we have
to work with? Well, a freezer makes a temperature
gradient, -80C inside, +20C outside a delta of 100C more or
less. That and some insulation is it really. But we can work
with it.
The freezer electronics** don't need much power. This is
fortunate because thermoelectric generators don't make
much. But, enough. So, place a thermoelectric generator,
Peltier element, Seebeck device etc, with one side in
contact with the interior and one side in contact with the
outside. The 100C gradient will be more than enough to
power the electronics so that they can do their thing
during a power failure. Solid State, no battery required.
Should be more reliable.
*Same guy that decided to put 12 freezers in a "freezer
farm" for organization and that "freezers make cold, not
heat! Why do the HVAC guys need to be involved? We
already spent a fortune on all the extra high capacity
electrical outlets"
**like microwaves, designed in 1981 and never changed.
not this
https://www.youtube...watch?v=D76jSwRIivg
a small in-fridge unit might be the way to go. [wjt, May 31 2020, last modified Jun 04 2020]
[link]
|
| |
Retrofit? Probably not. You'd need to cut holes in insulation
etc. It's just a thing that could be built-in for a small cost. |
|
| |
Preventative maintenance isn't avoidable. -80C freezers
build up ice at extraordinary rates, particularly in humid
summers. They also have air filters that need to be cleaned.
They're something that really should be kept on top of, but,
that would have to come from someone's time/budget. |
|
| |
No problem can't be solved with the proper application of high explosives. Your administrator sounds like a problem to me. |
|
| |
//proper application of high explosives// Yes, and judicious use of a shovel. |
|
| |
Come to think of it, the shovel is easily acquired, has no moving parts, no traceable serial number, can be used before, during, and after the removal process... a complete job, neat and clean and plausibly deniable, for less than the cost of Big Louie the explosive expert's lunch on the way to erase* the guy. |
|
| |
*except there's always DNA spatter |
|
| |
Thinning the lining of a box that is designed because of insulation doesn't sound sensible. A better retrofitted storage cell, charged off the mains, not unlike UPS would be my suggestion. Now days the newly inserted electronics will probably come with IoT and txt the affected people directly. |
|
| |
Widget's got the right direction. |
|
| |
I see a lucrative business. If freezers cost as much as a
Ferrari you should charge at least as much as a replacement
Ferrari component for these. And be sure to give them a
sciencey-name for the bean counters to struggle over. |
|
| |
//During the recent events, a remarkable amount of
equipment has failed.// |
|
| |
I blame the installation of 5G towers. I mean, why not? |
|
| |
//Thinning the lining of a box that is designed because of
insulation doesn't sound sensible.// |
|
| |
In theory, you're right. I am creating a thermal path for
heat energy to flow into the interior via the thermoelectric
generator. But,thermal conductivity would be small via eg.
a 45mmx45mm element. |
|
| |
In addition, there already is a hole through the insulation
allowing free gas exchange, it's there to equalize pressure.
Imagine a freezer full of stuff at -80C, you open the door
and rummage around for your stuff** while room
temperature air fills the freezer. You shut it and that air is
cooled rapidly, the pressure drops and your door is now
sealed. So they put a ~30mm hole through the door which
means you can open the door and ensures the freezer fills
with ice derived from water vapor in the air. |
|
| |
So I think you could build the thermoelectric generator into
the vent design. Retrofit isn't going to happen, but the hole
through the insulation is there to be designed around. |
|
| |
//A better retrofitted storage cell, charged off the mains,
not unlike UPS would be my suggestion. Now days the newly
inserted electronics will probably come with IoT and txt the
affected people directly.// |
|
| |
The electronics, lead acid battery and alarm relay already
function like this. The problem is somewhat institutional,
I'm trying to get around the battery failure mode by putting
in a solid state backup power supply that uses a large
energy source inerrant to the function of the device. It's a
bit like a ram air turbine (RAT) on a commercial airliner, if
your aircraft has lost both engines, you need SOME
electrical energy to give the pilots tools to mitigate the
problem. Sure the RAT adds drag and technically worsens
the glide ratio - but at that point the altitude & speed are
the only available energy resources and they can at least
get a radio call out. |
|
| |
*Is there a word more appropriate? It's more of a heat
collector.
**Global academic lab policy stipulates that there should
only be one left handed cryo glove available if at all, the
rest of the searching should be done with standard nitrile
gloves in a race against frostbite and the rapid
accumulation of frost over all the labeling that wasn't very
good in the first place. |
|
| |
//I see a lucrative business. If freezers cost as much as a
Ferrari you should charge at least as much as a replacement
Ferrari component for these. And be sure to give them a
sciencey-name for the bean counters to struggle over.// |
|
| |
No-one usually questions big purchases. It would be nice if
the layers of admin were in any way connected to some sort
of performance indicator, but that's tricky in science. It's a
strangely inverted power/responsibility dynamic where
admin controls the people who deliver science and obtain
the money to pay everyone and organize/maintain
everything in between. |
|
| |
BTW the old school back up method for power/compressor
failure was a temp sensitive valve that opened allowing fairly
rapid release of CO2 from an attached cylinder. |
|
| |
These aren't popular anymore, no-one likes paying for the
cylinder rental, the CO2 cylinder probably gets used for an
incubator emergency and not replaced, and the whole system
probably buys you a few hours. |
|
| |
Peltier junctions constructed as a layered mesh, in the 30 mm radius-ed cylinder form factor, might be a retrofit. Letting air in but still riding off heat entry. |
|
| |