Permeation of moisture out of EPDM rubber hoses

Aqueous coolants have a long history of reliable use in automobile engine cooling. Their use in computers is not new but the new requirement of fill and forget raises some challenges. While the temperatures to which coolants are subjected in computers are low, generally less than 60°C, the closed aqueous cooling loops in computers must operate the life of the machine with zero maintenance with no requirement for fluid replenishment. The paper describes the evolution of the test methods for measuring the permeation rates of water out of EPDM rubber hoses. Improved permeation rate measurement methods and results for de-ionized water and propylene glycol-based water coolants permeating out of EPDM rubber hoses are presented and generalized to provide moisture permeation rates out of hoses of any size given their outer and inner radii.