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Oil-Cooling 802.11 Infrastructure
gomoX writes "A group of 802.11b fans in Tordera, Spain, are running a wireless node on the roof of a building, with the idea of a free wireless network for everyone on the neighbourhood. Its a system running linux with a home made can antenna, mounted on a plastic tool box in the roof. To keep it cool under the sun and protect it from rain, wind, they have immersed it into vegetable oil (yes, the whole thing). As oil is non-conductive, everything should run fine. The site is in Spanish, here is the google translation and the google cache."
My experience with vegetable oil is that it fries in heat...how the hell does this work?
Wouldn't vegetable oil retain heat longer than the plastic and metal that it was intended to protect? I could see this thing getting very hot on a sunny afternoon.
The biggest problem with immersion based oil cooling is that it tends to soften PCBs. I suppose that, if you never really jiggle the setup, it will pretty much remain where you leave it (especially if you keep the oil cold and viscious), but it could cause problems.
funny munging
In Australia our major power supplier here does that for all of their high-tension cables that go underground - they're encased in a layer of plastic, but the rest is oil. It not only is cheaper and lighter than other sheathing forms, but it insulates and dissapates heat at the same time
Within a few weeks, especially up in the sun and even slightly open to contamination from the environment(toolboxes ain't exactly hermetic), the oil is gonna go rancid.
I wonder what the by-products of the little beasties will do to the components...
Con el disco duro creíamos no había problema porque dicen que vienen "envasados al vacío" pues ahora podemos decir que no se si todos son igual pero el que usamos en primer lugar NO lo estaba. Lo metimos dentro del aceite y funciono bien, incluso dejamos todo el sistema 2 días enteros funcionando dentro del aceite sin problema alguno, el problema vino al moverlo para colocarlo en el tejado, que fue cuando posiblemente penetro aceite en el interior y una vez en el tejado no arrancaba. Entonces tuvimos que bajarlo todo de nuevo y buscar otro disco duro, instalar todo el linux de nuevo y no meterlo dentro del aceite. O sea que atención: NO hay que meter el disco duro en aceite ya que por algún lado entra dentro si lo meneas un poco
Basically, they inmersed everything in the oil, including the HDD (they didn't need a CD-ROM or FDD) and they figured the HDD would work even though it had moving parts because they're vacuum-sealed. Not so, their first prototype worked for two days and then the HDD died as oil got into the drive mechanism. They had to look for another disk, reinstall Linux and the rest of the software and then figure out a way to keep the hard disk out of the oil.
So there you have it folks, never put your hard disks in Mazola - they die.
Fans are usually removed for this sort of thing. I've seen quite a bit of this with extreme overclockers. The idea is to fill a tank, like a styrofoam cooler, with oil. Drop in a fluid pump, like one for a fish tank. Pump the non-conductive oil OUT of the container, letting it spill over the cooling unit of a stripped window air conditioner, flowing back into the cooler. You can also add a filter to the process to help keep the oil clean.
It takes care of cooling the system -- they can get down to absurd cold temperatures.
There shouldn't be enough pressure for the oil to push itself under the contacts -- unless you immerse the motherboard down a few meters or so.
Ideally, if this isn't a web server and just an AP, they don't need a hard drive. They should switch to a 512 Mb compact flash drive or something with no moving parts.
Learning HOW to think is more important than learning WHAT to think.
I hear that in oil immersion based cooling the oil tends to seep in and interrupt any less than perfect soldering connections, causing mysterious errors.
Any word on this?
It's Christmas everyday with BitTorrent.
There's no reason to run more than half a meter of cable...
Use a small external radio, the sort that has three connectors: power, ethernet, antenna.
Keep the computer, hub, etc indoors and just run cat5 ethernet and some low voltage power cable up the the roof.
On the roof, mount the antenna and the radio. Put the radio in a small weatherpoof box, or even a reinforced plastic bag. You shouldn't need more than 40cm of cable. Heck, use a small adapter and mount the radio TO the antenna itself without any cable. Nearly zero loss.
These little radios aren't too expensive and can handle extreme temperatures. There's no reason to have long cable runs or a PCI/PCMCIA radio card.
Not too hard I would think to coat the motherboard.
Its called 'Conformal Coating', avaliable in silicon or acrylic as a spray-on.
You could just mask off a few sections of the motherboard (CPU socket, card connectors) and spray the board. Or just assemble it and spray the whole thing...
People who typically do total immersion cooling use mineral oil. It is a non-organic oil, so it doesn't spoil. Doesn't conduct electricity either.
Mineral oil is very similar to transformer oil, which is what electricity companies use to keep the transformers cool.
The oil pressure will work on 'both sides' of the contacts, effectively cancelling itself, so that the oil won't be forced under the contacts. As a matter of fact, putting PCBs into (hydraulic) oil has been done in sub sea robotics applications and tested down to below 3000 meters. You'll have to change/modify some components (chrystals, capacitors), but most components handle both oil and pressure quite well over time, including non-soldered connectors. Moving parts, like fans and hard disks are a bad idea in oil, but in under water applications, cooling is rarely a problem.
I'd prefer mineral to olive oil, though...
Look! No sig!
They removed almost every part of water in the oil to avoid problems (yes, a bit can be dissolved into oil)
They could have used mineral oil wich is less acid and would have worked well.
The thing about HDs is like this: they *were* vacuum closed in the beginning, but in some really dry and heat condition (texas, etc) they kinda explosed. So they started putting some small valves on them to avoid this: so the oil goes in.
My english is sow-sow. Sowhat?
There's a very good reason to put the WiFi equipment on the roof as close to the antenna as possible. Wiring to connect the radio to the antenna incurs massive signal loss, or is very expensive (and still incurs loss). It's generally accepted in the 802.11 community networking community ;-) that the best place to put the AP is in a tupperware or other similar weather resistant container right next to the antenna.
Your suggestion about mineral oil is smart IMHO.
simon
home page
A few years ago at a boat show I saw a product at one of the booths which looked like a translucent brown liquid, intended as an electronics waterproofing sealant. It was such a long time ago I don't remember the name of the product, but as a demonstration they had a portable B&W television submerged in the stuff and it was still operating fine.
One of my friends used to work at KFC and he had told me how nasty the old oil would get while it sat outside awaiting pickup for disposal. I guess the little leftover bits of chicken probably had something to do with it, but I'm assuming vegatable oil is a pretty friendly enviorment for bacteria to thrive in nonetheless.
---
DRM is like antifreeze, to the MPAA/RIAA it's sweet, to the consumers it's poison.
This is not the first time it's done. Let me tell you the whole history...
Since three years ago, Iberian hackers hold an annual meeting, called HackMeeting.
The first one (code named hmbcn00) took place in Barcelona (Catalonia), in a squat called Les Naus, in October 2000.
The second one (code named hmleioa01) took place in Leioa (Basque Country) also in a squatted house, the Udondo Gaztetxe, in September 2001.
Finally, last October, it was hold in Madrid the 3rd HackMeeting (code named madhack02).
As the previous meetings, it took place in a squat (El Laboratorio). This time gathered about 600 hackers.
It's not determined yet where the next HackMeeting will take place. Maybe somewhere in the countryside in Aragón.
Well, let's come back to the oil-powered PC.
In every hackmeeting there is a computer room, separated from the talks room. In the 3rd HackMeeting, the local HackLab (called Wau Holland 2001) had assembled a PC, put it in oil and placed in the computer room for public use.
I've placed a selection of pictures of the computer in oil (shot by Maky and Fernando Vicente) in my personal home page. Hope you like them.
Greetings,
Quique
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