Selecting Compounds for Wet Environment Applications
What Compounds Are Suitable for Wet Environment Applications?
In wet environment applications, consideration should be given to the jacket compound you choose on the cable of your custom interconnectivity solution.
Discover the best cable material and components for applications exposed to water.
Hydrophilic substances attract or bond with water on a molecular level, while those that are hydrophobic will repel water.
Water absorbed into polymers has a detrimental impact on its performance, such as reduced dielectric properties, dimensional variations and lower mechanical resistances. Therefore, hydrophobic substances are a desirable trait for a cable jacket that’s protecting your current-carrying conductors.
Choosing the Correct Compound
Compounds are on a spectrum of water resistance and the amount of exposure to water in the application will help determine the compound, along with other potential requirements such as listings or approvals.
PVC for example, would often be found as the jacket for a SJTW-rated 110V power extension cord. The ‘W’ in this rating refers to its weather resistance, which allows it to be exposed to water in an environment where it will dry out again. As most know, we use extension cords on a limited basis outdoors because they aren’t designed for permanent installation.
When exposure to water becomes more extensive, Northwire will often recommend a polyurethane (TPU), polyethylene (PE), or polypropylene (PP). In contrast to PVC, high-density polyethylene could be installed for longer periods of time completely underwater.
Eventually, water has a great propensity to ingress into flexible polymer compounds, unlike the rigid ones used for pipe installation in our buildings and homes.
To further combat this water ingress, the construction of the cable also becomes a factor. This is why we’ll add water blocking gels or tapes, silicone-impregnated coppers for the conductors or anti-wicking fillers that help further resist water’s movement or progression.
