S-Flex screwed pump flexible connectors S-Flex screwed pump flexibles are designed to help isolate vibration and noise from suitable pumps in chilled- and heating-water systems. The nylon-reinforced EPDM body uses steel-reinforced collars and BZP-coated carbon-steel unions. Available sizes 15mm, 20mm, 25mm, 32mm, 40mm and 50mm. Technical form