How to choose PPR pipes in different conditions?

Guidelines and selection for Pressure, Temperature, and Grade of PPR Pipes

PPR pipes are mainly divided into six series: S6.3, S5, S4, S3.2, S2.5, and S2, corresponding to different pressure ratings based on the total system usage (design) coefficient C:

When C=1.25, they correspond to nominal pressures of 1.0, 1.25, 1.6, 2.0, 2.5, and 3.2 MPa. When C=1.5, they correspond to nominal pressures of 0.8, 1.0, 1.25, 1.6, 2.0, and 2.5 MPa. The more common pipe series are S5, S4, S3.2, and S2.5. However, due to the significant reduction in the service life of PPR pipes at higher temperatures, when selecting pipes for hot water applications, it is generally advisable to choose a pressure rating one level higher than for cold water pipes. Typically, hot water pipelines use the S3.2 and S2.5 series, while cold water pipelines use the S5, S4, and S3.2 series.

When C=1.25, they correspond to nominal pressures: S5-1.25 MPa, S4-1.6 MPa, S3.2-2.0 MPa, S2.5-2.5 MPa, S2-3.2 MPa.

For selecting cold water pipes, if the water temperature does not exceed 60°C for an extended time and the system's working pressure is, for instance, 0.8 MPa, adding a water pressure of 0.25 MPa (industry experience) makes it 1.05 MPa. Then, multiplying it by a safety factor of 1.2 (determined according to the specific conditions) results in 1.26 MPa. If this exceeds S5 (1.2 MPa), then S4 (1.6 MPa) should be selected, and so on for higher pressure grades.

When selecting pipes for hot water, if the water temperature exceeds 60°C for a long time, start directly from S3.2 (2.0 MPa). For example, if the system's working pressure is 0.8 MPa, the nominal pressure would be calculated as (0.8+0.25)*1.2 = 1.26 MPa, and in this case, S3.2 (2.0 MPa) should be chosen. If the system's working pressure is 1.5 MPa, the nominal pressure would be calculated as (1.5+0.25)*1.2 = 2.1 MPa, and S2.5 (2.5 MPa) should be chosen. If the system's working pressure is 2.2 MPa, theoretically allowing for S2 (3.2 MPa), it is very close, and for safety reasons, PPR pipes should not be chosen; instead, consideration should be given to selecting metal pipes.

Note: ISO15874-2:2013 (E) Pipe dimensions and wall thickness requirements for different series.