PN (Pressure Nominal) is the pressure rating system used for HDPE pipes under IS 4984:2016. It tells you the maximum continuous water pressure the pipe can safely carry at 20°C over its 50-year design life. Choosing the right PN is essential — too low risks pipe failure, too high wastes money on unnecessary wall thickness.
Complete PN Pressure Rating Chart — IS 4984:2016
| PN Rating | Max Pressure (bar) | Water Head (m) | PSI Equivalent | Typical Application |
|---|---|---|---|---|
| PN 2 | 2 | 20 | 29 | Very low pressure gravity systems (PE 63 only) |
| PN 2.5 | 2.5 | 25 | 36 | Gravity flow, rural water supply |
| PN 3.2 | 3.2 | 32 | 46 | Low pressure distribution networks |
| PN 4 | 4 | 40 | 58 | Gravity-fed irrigation, rural water supply |
| PN 5 | 5 | 50 | 73 | Light pressure sprinkler laterals |
| PN 6 | 6 | 60 | 87 | Standard agricultural mains, sprinkler systems |
| PN 8 | 8 | 80 | 116 | Standard irrigation and town water supply |
| PN 10 | 10 | 100 | 145 | High pressure water supply, shallow borewells |
| PN 12.5 | 12.5 | 125 | 181 | Municipal distribution, industrial supply |
| PN 16 | 16 | 160 | 232 | High pressure industrial, deep borewells |
| PN 20 | 20 | 200 | 290 | Very high pressure industrial applications |
HDPE Pressure Classes (PN Ratings)
PN = Nominal Pressure in bar. Green = low pressure (gravity/drip), Red = high pressure (borewell/fire).
How to Choose the Right PN
- 1Find your pump's maximum discharge pressure (shut-off head) in bar — or divide metres of head by 10
- 2Add the elevation difference between pump and highest delivery point (metres ÷ 10 = bar)
- 3Add 20–30% safety margin for water hammer (pressure surges when valves close rapidly)
- 4Choose the next higher PN from the chart above
Example: Submersible pump at 60m depth with 4 bar discharge pressure. Tank is 10m above ground = 1 bar static head. Total = 5 bar. Add 25% surge margin = 6.25 bar. Choose PN 8 to be safe.
Which PN Class for Which Application?
Match your project type to the right pressure rating.
Drip Irrigation
Gravity-fed and low-pressure drip systems
Rural Water Supply
Village water distribution networks
Municipal & Borewell
Town water mains and shallow borewells
Industrial Mains
Factory water and chemical transport
Fire Hydrant Lines
Fire-fighting networks and pumped systems
Deep Borewells
High-head deep borewell riser pipes
PN by Application — Quick Reference
| Application | Recommended PN | Typical SDR (PE 80) |
|---|---|---|
| Gravity tank to field | PN 2.5 – PN 4 | SDR 41 – SDR 26 |
| Sprinkler mainline | PN 6 | SDR 17 |
| Drip irrigation main | PN 4 – PN 6 | SDR 26 – SDR 17 |
| Submersible pump (shallow) | PN 8 – PN 10 | SDR 13.6 – SDR 11 |
| Submersible pump (deep) | PN 12.5 – PN 16 | SDR 9 – SDR 7.4 |
| Municipal water supply | PN 8 – PN 10 | SDR 13.6 – SDR 11 |
| Industrial process water | PN 10 – PN 16 | SDR 11 – SDR 7.4 |
| Sewerage (gravity) | PN 2.5 – PN 4 | SDR 41 – SDR 26 |
PN and SDR Relationship by Material Grade
The same PN rating requires different SDR values depending on the material grade. PE100 achieves higher PN at the same SDR, or the same PN at a higher SDR (thinner wall, lighter pipe):
| PN Rating | SDR for PE 63 | SDR for PE 80 | SDR for PE 100 |
|---|---|---|---|
| PN 4 | SDR 26 | SDR 33 | SDR 33 |
| PN 6 | SDR 17 | SDR 21 | SDR 21 |
| PN 8 | SDR 13.6 | SDR 17 | SDR 17 |
| PN 10 | SDR 11 | SDR 13.6 | SDR 13.6 |
| PN 12.5 | — | SDR 11 | SDR 11 |
| PN 16 | — | SDR 9 | SDR 9 |
| PN 20 | — | SDR 7.4 / SDR 6 | SDR 7.4 |
Common Mistakes When Choosing PN
- Buying the cheapest PN 2.5 pipe for a pump-fed system — it will burst under pump pressure
- Over-specifying PN 16 for a gravity irrigation system — wastes money on unnecessary wall thickness
- Ignoring water hammer — rapid valve closure can create pressure spikes 2–3× the normal operating pressure
- Not accounting for elevation — a 50m hill between pump and tank adds 5 bar of static pressure
- Using PN rating at face value without checking temperature — PN ratings assume 20°C water temperature
Frequently Asked Questions
What does PN mean on HDPE pipe?
PN stands for Pressure Nominal. It indicates the maximum continuous working pressure the pipe can safely carry, measured in bar. PN 10 means the pipe can handle up to 10 bar (approximately 100 metres of water head).
What PN do I need for farm irrigation?
For gravity-fed systems: PN 2.5 to PN 4. For pump-fed sprinkler mainlines: PN 6. For borewell rising mains: PN 10 to PN 16 depending on pump depth and discharge pressure.
Does higher PN mean better quality?
No. Higher PN means thicker pipe walls, not better material. A PN 6 and PN 16 pipe made from the same PE100 resin are equally well-made. Buying PN 16 for a PN 4 application wastes money on unnecessary wall thickness.
Tools & Related Resources
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