TPE medical tubing with single-barb fitting is stronger than adhesive-bonded PVC

Eldon James Corp., a supplier of medical tubing and fittings, has published the results of tests it conducted to determine the toughness of tubing produced from Medalist thermoplastic elastomers (TPEs), manufactured by Teknor Apex Co., and the durability of connections between this tubing and single-barb luer fittings. 

In pull-apart tests of more than 1000 assemblies, the connections typically did not fail until forces greater than 8 lb were applied, more than double the requirement set by Eldon James' customer, according to Mark Timbrook, Marketing Director. In burst tests, the TPE tubing withstood average pressures of 500 psi before failure.

TPE's elasticity proved to have a two-fold advantage, says Timbrook. "It enhances the bond between tubing and fitting, in much the same way that the grip of a finger-trap toy tightens as you pull your fingers outward," he explains in a press release. "At the same time, within the parameters of our burst test, the resilience of the TPE prevents the tubing from rupturing. While PVC tubing would burst under similar pressures, the failure of the TPE tubing took the form of bulging."

Seeking an alternative to PVC tubing as well as the adhesives that are typically used to bond it with connectors, Eldon James produced a new range of tubing from Teknor Apex's Medalist MD-585 compound and paired it with USP Class VI–compliant single-barb connectors, which it also manufactures. Single-barb fittings make a better seal with TPE tubing than multi-barb connectors and achieve strength comparable to adhesive assemblies with PVC tubing, according to Timbrook. They are also less costly than adhesive assemblies, adds Eldon James.

Tubing compounds in the Medalist MD-500 Series exhibit crystal clarity and mechanical properties comparable to PVC, says Teknor Apex. They also provide similar clamp resilience and resistance to kinking and necking, have a similar feel, and are more flexible and less dense than PVC.

Medalist materials undergo minimal heat aging–induced color shifts after exposure to gamma sterilization, the company adds, noting that a typical compound in the series exhibits 70% less heat-aged color shift than a gamma-stabilized PVC compound of comparable hardness.