3.4 Definitions for the normative design of polypropylene pipes Service Pressure: The maximun pressure that can be handled by pipes intended to conduct liquids in constant use. Nominal pressure (NP): Alfanumeric designation related to the mechanical characteristics of a piping system components. It is used for reference purposes and its denomination is normalized according to ISO 161-1:1996. Safety Coefficient (SC): Specified according to the material and the aplication area. IPS applies the DIN 8077:99 Norm service conditions. For cold and hot water calculation, the safety coefficient used is 1.25; for heating, the coefficient is 1.5. SDR (Standard Dimensional Relation): Value that relates the dimensions of the pipe and it is obtained by calculating of the quotinet between the pipe’s external diameter and its thikness. SDR= External D Thikness Series (S): Adimentional number used to name the different types of pipes. It is set according to the ISO 4065:1996 Norm. S= SDR - 1 2 Design Stress: Of 6.3 MPa. for random polypropilene copolymer ( type 3 ) according to 13470:2005 IRAM EA1 standards. Comparison between Series (S) and Nominal Pressure (NP) EA1 13470:2005 S SDR PN ( bar ) 8.3 17 8.3 5 11 12.5 3.2 7.4 20 2.5 6 25 2 5 32 Nominal pressure and continual service during 50 years IPS Product Service Pressure and Working temperature Maximum resistance to pressure 120 Kgf/cm2 PN S 32 2 IPS Fusion Fittings 32.3 Kgf/cm2 at 20ºC Strengthened Fusion Multilayer 30.9 Kgf/cm2 at 20ºC 120 Kgf/cm2 25 2.5 IPS Fusion Multilayer 24.5 Kgf/cm2 at 20ºC 100 Kgf/cm2 20 3.2 15.5 Kgf/cm2 at 20ºC 80 Kgf/cm2 12.5 5 S3.2 and Maxum S3.2 IPS Fusion Pipe (Cold water) 17