mickeyrench
Senior Member
- Location
- edison, n.j.
can someone tell me how to pressurize a enclosure to keep outside air out that is distroying componets inside? thanks
pressurize boxes
- Thread starter mickeyrench
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Mr. Wizard
Senior Member
- Location
- Texas
Is it the air, or the moisture in the air? If its moisture then I would recommend using diseccants (did I spell that right?). They are the little packages that read "do not eat" on the outside, and feel like they're filled with little rocks. They usually come with control/computerized equipment.
mickeyrench
Senior Member
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- edison, n.j.
Mule , do we have to watch the pressure going in the enclosures? some enclosures are bibber than others. thanks again
If your in a classified area, I would say yes..but I cant tell you the pressure. If you just have a environmental issue that is in a general purpose area...I would use your scruples and a valve....just make sure you are not pumping more moisture into the enclosure as you will destroy its components....
winnie
Senior Member
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- Springfield, MA, USA
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- Electric motor research
This is outside of my area of expertise, but I have some qualms:
1) If the enclosure is not particularly gas tight, then you will have lots of gas flow needed to keep the enclosure purged. This can be very expensive in terms of the energy used to maintain the gas flow.
2) If the enclosure is gas tight aside from small leaks, then you have to be very careful about pressure control, using some sort of regulator. If you over-pressurize the enclosure, it could literally become a bomb.
How is this done when 'properly' engineered?
-Jon
1) If the enclosure is not particularly gas tight, then you will have lots of gas flow needed to keep the enclosure purged. This can be very expensive in terms of the energy used to maintain the gas flow.
2) If the enclosure is gas tight aside from small leaks, then you have to be very careful about pressure control, using some sort of regulator. If you over-pressurize the enclosure, it could literally become a bomb.
How is this done when 'properly' engineered?
-Jon
The ones that Ive seen in plants that are required in a classified area have guage showing that there is either positive or negative pressure in the enclosure, there is only a guage and a valve.....in some cases a pressure switch is required ensuring that proper pressure is being reached, but that's for classified areas.
Most enclosures that are 4x or 7 will clamp down tight enough to minimize losses......
As for the bomb, thats what a needle valve is for. So the only difference is the guage....your not going to get a good enough seal to hold that much pressure as it will leak before goes boom..
Not sure what the contaminate is - but you might consider a vapor-phase inhibitor. Hoffman has it available.
http://www.hoffmanonline.com/produc...0&catID=80461&itemID=3433&searchFor=inhibitor
76nemo
Senior Member
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- Ogdensburg, NY
petersonra
Senior Member
- Location
- Northern illinois
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- Semi-retired engineer
as a practical matter the gaskets on a typical enclosure won't hold more than a few pounds of pressure (if that), so chances are it won't become a bomb.
this can be a very effective means of keeping out contaminants. a few pointers.
1. Use a pressure gauge and regulator in lieu of a needle valve. It needs to be very low range. You only need perhaps a half an inch of pressure.
2. Have a shutoff valve for the air line.
3. Seal all the conduits entering the box. Expanding foam is a good choice. Air is extremely expensive.
4. Put a coalescing filter on the air coming into the box to get rid of water and oil, and other contaminants.
This sounds a lot like the dry air systems we had employed in our radar waveguides. While what you have is obviously on a much smaller scale what I can tell you is that vapor phase inhibitors, or pressurized air is going to do a lot better than desiccant because those are going to have to be changed out pretty often if you have any significant amount of moisture.
I would say a vapor inhibitor would be a lot easier to put in than a bunch of regulators and valves, but it's really a matter of how much you want to put into it, and how big of an enclosure you're talking about.
I would say a vapor inhibitor would be a lot easier to put in than a bunch of regulators and valves, but it's really a matter of how much you want to put into it, and how big of an enclosure you're talking about.
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