What does PN mean? PN stands for “Pression Nominale”, the nominal pressure of a pipe. The number indicates the maximum permissible operating pressure in bar that a PE pipe can withstand permanently (50-year service life) with water at 20 °C. A PN10 pipe therefore withstands 10 bar, a PN16 pipe 16 bar.
What does PN (nominal pressure) mean?
The nominal pressure PN is the central parameter when selecting pressure pipes made of polyethylene. It describes the maximum operating pressure for which a pipe is designed under reference conditions – that is, for transporting water at 20 °C over a calculated service life of 50 years.
The two most common pressure ratings in the garden and irrigation sector are:
- PN10 – up to 10 bar operating pressure
- PN16 – up to 16 bar operating pressure
The difference between PN10 and PN16 therefore lies in the load capacity: PN16 pipes withstand higher pressures because they have a thicker wall at the same outside diameter. This makes them more robust, but also heavier and more expensive – and the inside diameter turns out smaller.
What is SDR – and how is it related to PN?
While PN describes the pressure rating, the SDR (Standard Dimension Ratio) describes the geometry of the pipe. It is the ratio of the outside diameter d to the wall thickness s:
SDR = d / s
From this follows a simple rule of thumb for the pressure rating of PE pipe: a small SDR value means a thicker wall – and thus a higher pressure rating. A large SDR value stands for a thinner wall and a lower pressure rating.
Important: SDR alone does not yet determine the pressure rating. The material is also decisive, more precisely its minimum strength (MRS). That is why the same SDR results in different nominal pressures for PE80 and PE100. The assignment follows the calculation MOP = (20 × MRS) / (C × (SDR − 1)) with the safety factor C = 1.25 for water.
| SDR | Wall thickness | Pressure rating PE80 | Pressure rating PE100 |
|---|---|---|---|
| SDR 17 | thinner | PN8 | PN10 |
| SDR 13.6 | medium | PN10 | PN12.5 |
| SDR 11 | thicker | PN12.5 | PN16 |
| SDR 9 | very thick | PN16 | PN20 |
The most important assignments for PE100 are therefore: SDR 17 ≈ PN10 and SDR 11 ≈ PN16. With PE80, the values shift down by one step because the material is less load-bearing – the same SDR 17 here results in only PN8.
PE80, PE100, PE100-RC – briefly explained
The material designation indicates how strong the material is. The number corresponds to ten times the minimum strength (MRS) in MPa:
- PE80 – MRS 8.0 MPa. Older or simpler quality, today largely replaced by PE100.
- PE100 – MRS 10.0 MPa. Today’s standard. At the same wall thickness it carries around 25 % more pressure than PE80 – or, at the same pressure, allows a thinner wall and thus a larger flow rate.
- PE100-RC – “Resistant to Crack”. PE100 with increased resistance to slow crack growth, suitable for sand-bed-free and trenchless installation. Same pressure ratings as PE100.
Which pressure rating for which application?
For most garden and irrigation applications, PN10 to PN16 is the right choice. As a guide:
- Garden irrigation, drip and spray systems: mostly PN10 is sufficient, since the real mains pressure in the household is typically 3–6 bar.
- House connection, longer supply lines, higher delivery heads: PN16 offers reserves against pressure surges and pump pressure.
- Drinking-water lines: usually PN16 in PE100, often additionally DVGW-compliant.
- Pressure surges / pump operation: always plan one step of reserve – short-term peaks can exceed the nominal pressure.
Tip: better to choose one step higher if pressure surges, long lines or pumps are involved. The surcharge is small compared to the risk of damage.
Temperature lowers the permissible pressure
The PN specification applies to water at 20 °C. As the medium temperature rises, the permissible operating pressure drops significantly, since PE loses strength when warm. Rule of thumb: at about 40 °C, the permissible continuous pressure is only around 70–75 % of the nominal value. For warm media, you should choose the pressure rating correspondingly higher or use the manufacturer’s specifications on the reduction factor.
FAQ
What is the difference between PN10 and PN16?
PN10 designates a maximum operating pressure of 10 bar, PN16 of 16 bar (each with water at 20 °C). PN16 pipes have a thicker wall at the same outside diameter and thus a smaller inside diameter.
What does SDR mean for PE pipe?
SDR is the ratio of outside diameter to wall thickness (d/s). A smaller SDR value means a thicker wall and a higher pressure rating. With PE100, SDR 17 corresponds to about PN10 and SDR 11 to about PN16.
Which pressure rating do I need for garden irrigation?
For most garden applications, PN10 is sufficient, since the line pressure rarely exceeds 6 bar. With long lines, pumps or possible pressure surges, PN16 is the safe choice.
Is PE100 better than PE80?
PE100 has a higher minimum strength (MRS 10.0 instead of 8.0 MPa) and carries around 25 % more pressure at the same wall thickness. PE100 is the standard today; PE80 is only rarely used now.
Standards and trust
In Germany, PE pressure pipes are manufactured according to DIN 8074 (dimensions, wall thicknesses) and DIN 8075 (material and test requirements). For drinking-water applications, approvals according to the rules of the DVGW are also decisive. When buying, look for the continuous pipe marking with material (e.g. PE100), SDR, nominal pressure and standard.
To join the pipes, depending on the application, detachable compression and PE fittings or permanently tight electrofusion fittings are suitable. How to choose the pressure rating, diameter and connection technology to match your project is shown in our guide Planning your irrigation.
Are you unsure about the design? The expert advice from KLN helps you find the right combination of material, SDR and pressure rating for your application.