A 20-hectare drip scheme and a 200-hectare sprinkler scheme need different pipe, but both fail for the same three reasons: too thin a wall at the pump, too few air valves, and fittings that do not match the pipe class.
The pressure question, in irrigation terms
Working pressure at the pump is not the number that matters at the far end. Friction loss along a long line means the head at the last hydrant can be a fraction of the pump pressure — and that is a design decision, not a pipe decision. What the pipe must survive is the pump head plus surge, and the static head when the line is shut in on a slope.
| Situation | Practical class | Note |
|---|---|---|
| Gravity-fed furrow or basin | PN4 – PN6 | Thin wall, cheap, coil |
| Drip with a booster pump | PN10 | The common export choice |
| Sprinkler, high head | PN16 | Surge matters on fast valve closure |
| Sloping ground, shut-in line | PN16 | Static head can exceed pump head |
Coil, and why it is the default
Drip and sprinkler laterals are laid in long runs with few branches. A 100 m or 200 m coil eliminates joints in the field, which is where irrigation lines leak — not in the pipe, in the joint made at 40 °C by someone in a hurry.
- DN20–DN63 — coil of 100 m / 200 m, laid by hand or with a simple uncoiler.
- DN75–DN110 — coil of 50 m / 100 m, needs a machine to handle.
- Above DN160 — straight lengths; a coil is no longer practical.
Layout mistakes that cost a season
- No air valve at the high point — air locks look like a pump problem and get diagnosed as one.
- No flush valve at the end — sediment accumulates and the last emitters starve.
- Undersized main — friction loss eats the pressure; the pipe is the cheapest part of the scheme.
- Fittings from a different class — a PN6 elbow on a PN10 line is the leak you will find next year.
- No spare coil — one cut by a plough means a day without water.
What we quote for an irrigation scheme
Area, crop, emitter or sprinkler spacing, pump head and flow, total main length, and the topography. We return a main diameter, a class per section, the lateral coil quantity and a fitting list. If the scheme is being designed by an agronomist, send their drawing and we will quote against it.