A helpful initial step to eliminate enclosure moisture is to characterize the enclosure environment using a temperature/humidity data logger. These inexpensive, battery-powered devices (~$200) record Dry Storage Cabinets. Additionally they indicate the dew-point conditions inside the enclosure (Fig. 6). Maintaining enclosure temperatures above dew-point temperatures is a requirement for condensation prevention.
Pursuing this alternative can be accomplished in a number of ways, starting from desiccant to thermoelectric dehumidifiers-the process would be to select a choice which is inexpensive to both implement and sustain. Water-absorption ability of desiccant is determined by many different factors (e.g., desiccant type, humidity, temperature). For example, silica gel can absorb up to 40% of the weight in water. A 4’ x 6’ x 2’ electrical enclosure in a hot/humid environment would saturate 125 g of desiccant in approximately 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, when it comes to desiccant regimes, each act of opening an enclosure to examine the desiccant may serve as an air exchange.
Dehumidifiers are relatively inexpensive, although finding convenient available power inside an enclosure may be problematic. The positive feature is the fact dehumidifiers get rid of the manual intervention associated with a desiccant regime. The negative feature of dehumidifiers is because they introduce an additional device that can ultimately fail.
Another method is to minimize the chance of condensation through internal heaters (or light bulbs) to maintain the internal enclosure temperature well above dew-point temperatures. The downside is the fact higher temperatures may be detrimental to a few heat-sensitive electronic components, as well as the higher temperature actually allows the air to hold more moisture. Venting and fans can aid in avoiding condensation in some situations-even though the Dry Cabinets For PCB Storage still exists. One interesting product the makers of GORE-TEX® have produced involves screw-in vents that enable enclosures to breathe, while providing a barrier to moisture and contaminants. The theory behind this type of venting is that it reduces the stress on door seals when you can find pressure differentials in between the enclosure and the environment. By equalizing pressure, the chance of moist air at higher pressure defeating your door seals is lessened.
Moisture-hardening of electronics includes many different techniques. In terms of connectors, using waterproof connectors or hardening existing connectors and splices with heat-shrink tubing can be useful to minimize water intrusion and corrosion. Avoiding horizontal orientation of components like printed circuit boards inside the enclosure can minimize surfaces where condensation may collect for extended periods of time. Conformal coatings for lower-voltage printed circuit boards and using potting (see Fig. 7) of higher-voltage components greatly raise the moisture resistance of components. Potting costs vary according to the dimensions of order, material selection jmmhra part geometry, but representative costs for tiny orders (less than 10) typically fall within the range of $18 to $45 per part. An extra benefit from potting is the added protection from shock and vibration.
Moisture protection of electronics is better approached by pursuing practices that maximize Dehumidifying Dry Cabinets during equipment installation, along with being ready to mitigate failure through any one moisture-protection measure during operations. This plan, together with tracking equipment-maintenance performance to know how well moisture-protection measures work, can lead to long-term minimization of electronics moisture-induced problems. MT.