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How to Run a Computer in a Sub-Zero Environment?
Underdog asks: "I've seen tons of Slashdot articles on cooling hardware, but my company may be taking on the task of wiring a large sub-zero (as low as -14) warehouse with temperature sensors and the requisite network equipment and computers to read them. Our initial proposal includes at least a dozen acquisition computers, hung from the racks in the freezer. Does anyone have any experience with installing computers in extremely low temperature locations?"
I have no experience with low temperature settings, but would assume that the main problem would be water condensating on the warmer parts of the computer. So the question would be how to make sure that the water does not short circuit anything. Experience may be taken not only from environments with low temperatures, but also from areas with very high humidity, which might cause similar problems.
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Most important thing is to use a stable operating system, that way it doesn't freeze up.
Thanks folks, I'll be here all week!
Just use any of the Intel processors produced in 2005. Of course, you might have to beef up the A/C to keep the warehouse from thawing...
I once worked for a company that had a computer closet on top of a mountain.It would often get -25 to -50F and sometimes much much lower. If you can find a way to enclose the computers they will keep themselves warm. We just put up some 1"-thick insulation inside the walls of the little shed and the two computers kept it at 40-50F in there at the worst times.
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I left a Mac g4 dual Proc on my back porch in Connecticut for over 3 years summer winter and fall sometimes in winter the keyboard would be covered in snow and I would just turn it over anrd let it dry out it's still working today. I wish I had a Dell siting next to it for a comparasin.
Sorry about spelling and grammer
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This may be missing the point of the OP, but why not install the computers elsewhere and use something like the Sensatronics sensors? The sensor device can be outside the freezer - only the probes need to be in that brutal environment. The device connnects via Ethernet. We monitor using Intellipool Network Monitor, although before we had that package I threw together a Perl script to poll the devices via snmp.
The hard disk is the big problem. It will produce enough heat to keep itself warm and working if installed in an insulated box. It must be kept on at all times or an auxiliary heat-source like a light bulb must be provided when the drive is powered down.
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When some overclockers use sub-zero equipment, condensation becomes a big issue. With stuff like LN2, some OC'ers dump the entire motherboard into a non-conductive tray of oil. You could look into something like that.
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Since cold air has a lower capacity to hold water, warming the air should decrease the relative humidity of the air, bringing you farther from the dew point and make condensation less likely. Just let everything sit in the cooler to get nice and cold before you turn anything on and I think it should be just fine.
It's just for things like water blocks with peletiers where the ambient air temp is really right and the heatsink is super cold that you have condensation issues (like a can of pop.) With the extremely cold (and thus dry) ambient air this issue goes away.
My only concern would be if the freezer was often open for long periods of time letting in warm moist air, but even then I would expect it to condence on cold surfaces like the outsides of your cases, etc, and not on places that will short out.
Transistors are designed to behave within a specific range of voltages and switching speeds for a particular range of temperatures. Most COTS electronics are targeted for an ambient temperature around 72F and work best at that temperature. When temperature extremes are needed, the transistors are actually doped and constructed differently.
That having been said, there are some things you can consider:
1. Do the computers really need to be in the freezer? If there is a way to build it so that they're not in the freezer, do it.
2. Enclose the cases with no ventilation. At subzero ambient temperatures they'll lose enough heat through the chassis. Insulate until the internal temperature is reasonable but not so far that it'll retain too much heat.
3. Install an electric heating coil in the case to bring the temperature up if it drops too low.
4. Underclock everything on the system: the CPU, the PCI bus, etc. Stretching out the clock cycles should give you a greater tolerance to the change in how the transistors behave and lower than expected temperatures.
5. Don't forget to consider the impact of the heat load on the freezer. You said computers with an S. Each one is going to dump 200 watts or more of electric heat into the freezer 24/7. Does the freezer have enough excess capacity to handle that and still do its job?
Moderating "-1, Disagree" is simple censorship. Have the guts to post your opinion.
Putting heaters (computers) in an environment meant to be cold is just adding to the cooling workload. If the computer is at any decent operating temperature, it's going to be heating up the immediate surrounding area, and you don't want that.
Put the computers outside. String sensors as needed. If you have to have electronics near the business end of the sensors, put those electronics under the floor or over the ceiling.
Think of your refrigerator. Would you put even a small computer in there to keep your food warm?
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At least Panasonic Toughbook-29 seems to meet your temperature (and humidity) specifications:s t.asp#12
http://www.panasonic.com/business/toughbook/df_te
Though that is only part of the solution...
--Saval
Taking advice from people who can't keep their server running isn't advised.
During the Cold War it was proposed that a live chicken placed inside of nuclear bomb would be sufficient to keep things from freezing up. In the case of a computer I would suspect the ambient heat of the electronics would be adequate to keep things at a reasonable tempurature provided the compartment and insulation was good enough.
For what it's worth, we've always built room-temperature enclosures to house electronics gear and PCs for the work we do in Antarctica. It's almost always easier and cheaper then trying to insure all your equipment can survive harsh temperatures.
For the odd piece of gear that needs to survive out in the open, we test them thoroughly in a freezer ahead of time. Some things - in particular simple solid state single board gear with no moving parts - seem to do quite well down to -50 C or lower. But, as capacitor values drift and sockets and connectors contract, even some likely candidates fail. Anything with lubricants or precision mechanical parts (drives, fans, etc) are almost certain to cause trouble. Expect your batteries to die and a some read-write storage media to fail.
But, is it really necessary to put a dozen full computers in this environment? It sounds like serious overkill to run a bunch of temperature sensors. If you absolutely need to use PCs, see if you can place them just outside of the cold space and run cables. Or, if that's not possible, put them all in a single, insulated, enclosed space with an active thermostat and some electric heaters. Make sure that when all the PCs are running at full tilt the temperature in the box is slightly below your target, so that you can control it with only a heater.
Better yet, replace the PCs with small readout and control boards. If all you need is to record temperatures to within a few tenths of a degree, building a board that will give you dozens of channels and a straightforward digital interface should be a few day's work for a reasonably competent engineer - and fabbing them may well cost less than a dozen PCs. You can then hand pick parts and packaging that is rated (or tested by you) to low temperatures, or you can build in very small heaters that keep individual parts warm without dumping too much heat into the environment. You may even be able to find such a product off-the-shelf if you hunt around.
If you absolutely must have PCs, see if you can't find a small single-board computer that will do the job. Test several over dozens of thermal cycles in a freezer before deciding to use it, and buy a bunch of extras.
I've done stuff like this with computers for balloon payloads that go up in the stratosphere, where it's around -50 C. Here's two tricks that should help. Trick number one is build a box out of styrofoam building insulation and duct tape. Assuming you're in the US, you'll see a number printed on the insulation like "R5" or "R10." That's the thermal resistance, in BTUs, hours, deg F, and square feet. No, I'm not making that up. Guesstimate the power dissipation of the computer and use that to make the first design, then test and iterate. You'll want to stick a thermometer on the case or other convenient location. If this isn't reliable enough, then trick number two is design your insulated box to run a bit cold, and build a thermostatically controlled heater. We usually designed our own, because we like to do things the hard way, but I believe at someplace like Newark Electronics you can buy a little package that contains a heater and a bimetallic thermostat, you just supply the power.
I've done lots of industrial installations, in places where -14 would be considered 'toasty warm' compared to outside temps in the middle of winter. If I saw a proposal that includes putting full blown computers in the freezer, the first thing I'd do, find another vendor, this one obviously has no clue when it comes to embedded industrial equipment. Mil grade sensors that are good to -40, may not be a dime a dozen, but, there's lots of them out there that you can just buy and install, which will happily feed the data back to a computer sitting in an office somewhere.
The bottom line, if you are going to put rack mount pc's inside the freezer, do your customer a huge favour, and reccommend they find an expert in the field. You will be saving yourself a long term support nightmare, and your customer a whole big pile of money, because the proposed solution is kind of like taking money and flushing it down the toilet.
You looking on slashdot, you dont need a IT guy, you need a good controls guy.
This is cakewalk for them.
You will want a HMI for instance google for Wonderware.
Field sensors can be done is several ways.
PLC's with say up to 128 thermocouples, which would be in enclosures to keep out moisture (nema 4) talking to ONE
pc or mutiple (MMI) (Man Machine Interfaces) vi tcp.
If I knew your layout, I could tell you completely. But really, get a good controls or I/E guy.
Use intel Pentium 4's. They get hot enough to keep the rest of the electronics warm. ;)
But seriously. Seal them off in a little cabinet. and keep that cabinet warmer. At least, say +5 celsius, that's about 40F so that conedsation doesn't form on the electronics and short it out.
Remember, electronics run on smoke, when the smoke gets out they stop working.
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Not true. It will have low humidity, but not zero. However, if the air around the computer is heated from the computer itself, I would be surprised to see any condensation. Low humidity air being heated should be able to hold more water not less. Condensation happens from moisture in warm air coming into contact with cool or cold air. This would be the opposite of what is happening in the freezer. As someone else mentioned, different thermal expansion rates of the computer hardware is probably more of an issue than humidity.
Bottom line, shop for equipment built for the job. If you have a need for this now, it is a very, very good bet that someone has done the same or similar before. I'll guarantee that you aren't the first person to have a need to run computer equipment in low temperatures. You've heard this before, and now, once again: "Don't re-invent the wheel."
For example, in a past life, we needed a gas analyzer shed full of, well, gas analyzers (Gas Chromatography TCD/Mass Spec, associated remote computers, etc.) that would pull in and analyze gas from several process lines. It was basically an insulated hut that sat outside in what could be as low as minus 50 degree celcius temperatures (not counting the bullshit windchill people like to brag with). And yes, it had heaters in it to make sure a the inside temperature was at least around plus 5 degrees C. This is the first time we needed something like this, but yes, there were several suppliers with that kind of experience available who were able to provide bids for the work. Even though it was the first time for us, we weren't breaking new ground. :-)
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