Domino Effect in Rubber Tubing Design

A long standing Hygenic customer, using Hygenic natural rubber tubing as part of their pumping system, began to notice discoloration of the water after use in their system. This discoloration caused user concerns about whether the apparatus was functioning properly.

The customer’s pumping system had recently evolved, but the tubing formulation had not been part of that evolution. The application had a high likelihood of ozone exposure and therefore the tubing was originally formulated to have high ozone resistance. The discoloration was foreseeable as antiozonants; this chemical family in particular, are known to cause staining and will leach from the tubing. Hygenic confirmed this by preparing samples with and without the antiozonant and leaching the samples in water. The tubing formulation containing the antiozonant discolored the water while the tubing formulation with no antiozonant did not. Further testing also indicated that while this discoloration is disconcerting to the end user, there was no indication that the tubing properties were significantly compromised.

Our recommendation was a joint development project to identify a technology that would replace the antiozonant with a non-staining/ less leachable alternative while maintaining the ozone resistance of the current formulation. A secondary option would be to eliminate the antiozonant, but this option was discounted as being too high risk for tubing failure in the end use application.

We successfully replaced the staining compound in a new formulation with a non-staining/ non-leachable alternative. We were able to achieve comparable ozone resistance without compromising any of the other product requirements. The customer conducted an extensive evaluation of the new formulation and implemented it across all product lines.

In summary, the “domino effect” is alive and well in providing custom components with product design. Any change in a product, no matter how simple or seemingly innocuous, needs to be reviewed with the component supplier to be sure there are no unintended consequences.