A helpful first step to remove enclosure moisture is to define the enclosure environment utilizing a temperature/humidity data logger. These low-cost, battery-powered devices (~$200) record Low Humidity Control Cabinets. In addition they indicate the dew-point conditions in the enclosure (Fig. 6). Maintaining enclosure temperatures above dew-point temperatures is a necessity for condensation prevention.
Pursuing this option can be accomplished in a quantity of ways, ranging from desiccant to thermoelectric dehumidifiers-the challenge is always to select an alternative that is inexpensive to both implement and sustain. This type of water-absorption capability of desiccant is dependent on many different factors (e.g., desiccant type, humidity, temperature). As an example, silica gel can absorb as much as 40% of their weight in water. A 4’ x 6’ x 2’ electrical enclosure in a hot/humid environment would saturate 125 g of desiccant within two air exchanges. Therefore, the resulting frequency of required desiccant change-outs (which affects maintenance costs) is basically driven by how well the enclosures are sealed. Unfortunately, in terms of desiccant regimes, each act of opening an enclosure to inspect the desiccant serves as an air exchange.
Dehumidifiers are comparatively cheap, although finding convenient available power inside an enclosure may be problematic. The positive feature is the fact that dehumidifiers remove the manual intervention associated with a desiccant regime. The negative feature of dehumidifiers is they introduce an additional item of equipment that can ultimately fail.
Another strategy is to reduce the opportunity of condensation through internal heaters (or light bulbs) to keep the interior enclosure temperature well above dew-point temperatures. The down-side is that higher temperatures may be detrimental to a few heat-sensitive electronic components, and also the higher temperature actually allows the air to hold more moisture. Venting and fans can aid in avoiding condensation in certain situations-even though Dry Storage Cabinets For Optics still exists. One interesting product the designers of GORE-TEX® have produced involves screw-in vents which allow enclosures to breathe, while providing a barrier to moisture and contaminants. The theory behind this type of venting is it decreases the stress on door seals when you can find pressure differentials involving the enclosure and the environment. By equalizing pressure, the chance of moist air at higher pressure defeating your home seals is lessened.
Moisture-hardening of electronics includes a number of techniques. When it comes to connectors, using waterproof connectors or hardening existing connectors and splices with heat-shrink tubing can be useful to reduce water intrusion and corrosion. Avoiding horizontal orientation of components like printed circuit boards in the enclosure can minimize surfaces where condensation may collect for prolonged periods of time. Conformal coatings for lower-voltage printed circuit boards and the usage of potting (see Fig. 7) of higher-voltage components greatly increase the moisture resistance of components. Potting costs vary in accordance with the scale of order, material selection jmmhra part geometry, but representative costs for very small orders (under 10) typically fall inside the range of $18 to $45 per part. An extra advantage of potting is definitely the added protection from shock and vibration.
Moisture protection of electronics is best approached by pursuing practices that maximize Desiccant Dry Cabinets during equipment installation, along with being ready to mitigate failure through anyone moisture-protection measure during operations. This tactic, in addition to tracking equipment-maintenance performance to comprehend how well moisture-protection measures work, can lead to long-term minimization of electronics moisture-induced problems. MT.