Danfoss AF-range impulse tube set (OEM designation "Impulse tubes for AFPQ4 PN40 15/20"). The impulse tubes connect the diaphragm chamber of a Danfoss self-acting AF-range pressure/flow controller actuator to the pressure-sensing tapping(s) on the pipework, transmitting the pipe pressure to the actuator so it can hold the set differential pressure or flow. This set is matched to the AFPQ4 controller on valve size DN 15/20 at PN 40. Tube outer diameter 10 mm; union connection G 1/4; material Stainless steel. Permissible medium: District heating/cooling circulation water. OEM P/N 003G1378. EAN 5702421812280. Technical data quoted verbatim from store.danfoss.com (code 003G1378).