Standard Dimension Ratio

Standard Dimension Ratio (SDR ) is a common classification of plastics pipes measure that reflects the ratio between the outer diameter and wall thickness of a pipe:

Tube outside diameter:

Pipe wall thickness: s

The SDR- number is used to specify the pressure resistance; in order to ensure a certain amount of resistance to pressure, depending on the material a particular SDR number is necessary. The following applies:

• the larger the wall thickness, the smaller the SDR number

• the smaller the SDR number is, the pressure-resistant tube

Commonly used are the SDR numbers: 11 (with material PE100 = PN16, safety factor of 1.25 ), 17 (with material PE100 PN10 =, factor 1.25 ) 17.6 and 33