12 mm (0.47 Inch). For all your Pumping & Process Requirements Pumps, Tanks, Vessels, Pipe Work etc. Dellmeco dm50/565-pee 2 air diaphragm pump polyethylene body-epdm-ptfe seals dellmeco's dm polyethylene range offer bsp connections as standard that are able to rotate 180 degrees, their diaphragms are completely smooth on the liquid side surface, with no metal coming in to contact with the liquid.