Airtight case

C

chopsuwe

[H]ard|Gawd
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Oct 2, 2001
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We have a client in a city with a large amount of geothermal activity. The workstations we have installed are only lasting 4 months before all the hydrogen sulphide in the atmosphere corrodes any exposed copper on the boards. The charcoal filters in the building's air conditioning can only so so much to help. The machine will be fine as long as we can keep the outside air from getting to it.

I have looked at covering the boards in a conformal coating but that leaves the connectors exposed. I'm not too keen on water cooling as this thing needs to be able to run for years with no maintainence. Sticking the whole thing in a sealed aluminium case could be an option but how big would it need to be?

The workstation in question is a Dell Vostro 200 slimline, which consumes about 80W according to the spec sheet.
 
Your problem would be cooling it with no airflow. Maybe a low-power MB and ultra-low-power CPU are in order for this one - Socket P + mobile CPU. It would be somewhat pricier - in fact a laptop might be cheaper/easier to get for the same power. However, even 20W can get nasty unless you get some cooling. If a large box doesn't work on its own, you might be able to rig up a closed-circuit air cooling system with a radiator/heat exchanger. That keeps the air inside the case in the case and the air outside, outside.

Another possibility, especially if hands-off reliability is critical, is to buy a sealed computer specifically made for those kinds of environments using components that are reliable at higher temps.

For the cost of a DIY system (once you include labour), you might pay for a sealed computer.
 
80w would be tough... with 20w or so, you could use a large thermal pad to link the mobo to the back panel of the case... Then maybe some watercooling would be in order... Moving the heat from the CPU to the case body.
 
The problem is in the building, or location of the building.. If these computers are dying in 4 months due to H2S, I can't even imagine the health of the employees using them. That gas is pretty toxic to humans, and at minimum, everyone in that office would have severe lung/eye problems. Even 2 particles per million in the air causes reproductive problems. Anything over 50 particles per million can cause severe bodily damage.. and that's just for short exposures. Above that you're risking death, especially for long exposures over a few minutes.

But if this is just a remote location where computers need to be for some reason unattended, then I'd go with a rough environment mini-ITX passively cooled computer, and have it sealed. There are plenty of military options that will meet those requirements.
 
rofl.. that would be a great solution for a client.. :rolleyes: Especially when the oil allows for breeches of contacts after molecular level breakdowns occur. It isn't a stable solution.
 
what about building an outside box that has better air filtration, that passes on clean air to the case inside.
 
whoa.... H2S???? Man, I hope people aren't being exposed to that. I'm assuming they wear H2S monitors clipped to their clothing? (I have one of those, because a lot of my clients are in the petro-chemical industry).

Like someone else in this thread said- that's nasty stuff.

Hydrogen sulfide.... that's H2S.... right? Are you sure that is what you are dealing with? Hell, fuck the computers- save the people....

Perhaps the concentration is below the unsafe limit, and just enough to corrode the boards?
 
what about just installing some heavy duty filters on the case? It might improve the lifetime a little bit.

Or do they have some sort of server room that gets better air? maybe you can do some sort of sealed low power thin client type machine that connects to a server.
 
TOOL1075 said:
whoa.... H2S???? Man, I hope people aren't being exposed to that. I'm assuming they wear H2S monitors clipped to their clothing? (I have one of those, because a lot of my clients are in the petro-chemical industry).

Like someone else in this thread said- that's nasty stuff.

Hydrogen sulfide.... that's H2S.... right? Are you sure that is what you are dealing with? Hell, fuck the computers- save the people....

Perhaps the concentration is below the unsafe limit, and just enough to corrode the boards?
Click to expand...

They all wear HEV suits and have crowbar next to their coffee mug :D
 
how about a case completely sealed with 1 exhaust port that has a vantec tornado.. that should keep the H2S out right?
 
You said you had looked at conformal coating, but did you also look at protecting the connectors with dielectric grease?
Otherwise since you've said water cooling is out of the picture I'd second the above posts for improved filtering/isolated environmental control.
Although, any chance of doing some sort of thin client solution?
 
A NEMA box is the industry standard. They are air/water tight and designed for outdoor use in environments like that. I have run computers in them before, and as long as you get one big enough, heat is not a huge problem (which is not to say not any). The only downside is the high price.
 
I think it should be possible to build an airtight yet air cooled case, but it will be tricky... I can see a couple of ways of doing this, though.

1: Run ducts between the intake fans and exhaust fans, isolating that airflow from the system. Meanwhile, within the airtight case, use other fans to create convection. If you can get the air passing over the ducts, you MIGHT get enough heat transference, but I doubt it.

2: If you can work with custom heat pipes you could use a similar method. Still use ducts, but use heat pipes to channel the heat away from the CPU and such, directly into the pipe where you place a heat sink. Difficult to do but more likely to work.

However, another poster's suggestion of a water system sounds more sensible.

btw, hi everyone.
 
Thanks for the link to the NEMA cases I thought there must be something like that available.

I think we will have another look at the conformal coating and dielectric grease idea for the time being. A toughbook could be an option but 6x teh price.

The whole city is built in a geothermal area. Every so often there will be a large bang and another house will disappear in favour of a geyser. H2S is the least of the worries. In low concentrations it is pretty harmless to humans but fatal to electronics. The building has filters which are rated for 6 months use but need to be replaced every 4 weeks. And this workstation is located in the server room!
 
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