Clean Air Partners (CAP), a manufacturer of dual-fuel truck engine systems, has acquired HIS Emissions Reduction Systems, which builds catalytic emissions reduction technology. Terms of the deal were not disclosed. San Diego-based CAP said HIS has sold its Catalytic Silencer products, which consists of an integrated catalytic converter and exhaust silencer, to various industrial global markets since 1977. CAP CEO Dan Kabel said the HIS acquisition would enable his company to offer catalytic reduction systems to its trucking customers. Kabel said HIS would become a division of CAP and maintain its facilities in Houston, TX. Harold Harris, founder & president of HIS, will serve as technical director.