Condensation within an aluminum enclosure

[RFguy]

We have a device that is enclosed within an aluminum enclosure. There is a small hole (0.189 inch diameter) that is covered with a unique water filtering fiber. Thus, water will is prohibited from following through the vent however water vapor, although restricted will pass. Our major concern is about water vapor. Water vapor will pass thru the filter and cause problems with condensation within the unit, since the unit will move from an outdoor to indoor environment. What methods can be used to reduce condensation from occuring within this aluminum enclosure? Is a disiccant useful or will it over time just become a problem? Temperature range is -40C - +85C. Humidity levels 20% - 90%.

 

[prodeng]

Dessicant may be a good option as long as you remember it does have a finite life. Once it has adsorbed all it can, you have to dry it out or replace it. Dessicant manufacturers probably have a way to calculate useful life. If relative humidity is the problem as opposed to the absolute amount, perhaps you could have the enclosure exchange the total volume of air at certain points in time to eliminate excess moisture content. Hope this helps.

 

[paddy]

Keep temperature 5 Deg.C above ambient to keep above the dew point. A small heating element may help.

Alternatively, do you need to have vent at all. Can you fit a simple expansion bellows and keep cabinet sealed with some dessicant inside which will then last for a very long time.

A couple of thoughts.