Task

Our customer required a cable for RTD temperature measurement that can withstand the temperatures and humidities of the application environment and has no outgassing. The cable must only have a minimum of capillary action and the outer jacket surface must be round in order to ensure that it can be sealed tightly.

Technical challenge

First, the so-called stress cracking resistance must be granted, which may occur in fluoropolymers if they are subjected to drastic temperature change cycles. Next the material-related problem needed to be solved: as these materials can only be extruded as a tube they show significant convolutions when stranding thus the cable looks like a spiral and does not have the required circular cross section.

Solution

For the conductors and braided shield we chose silver plated wires in order to assure protection against corrosion. A special cross-linked inner jacket minimizes the capillary action and offers a clean round radius, resulting later in a perfectly round outer jacket. All materials are certified by the manufacturer to be extremely resistant to stress cracking and have FDA approval and thus prevent the contamination of the application field.