Dripline selector
Picking a dripline starts with three questions: how many seasons it must last, whether the land slopes, and how long the rows are. Drip tape suits one season on level open fields, a thick-wall line suits greenhouses where it stays for years, and a pressure-compensating (PC) line suits slopes and pots. The tool also shows the Rivulis series in Perge’s catalogue that fit, and the longest row one line can water evenly.
Loading the calculator…
A worked example
Peppers on an open field in Aksu. Rows are 150 m, the land is level, the soil is loam, and the line is for one season. Emitters every 30 cm at 1 L/h, 1 bar at the line’s inlet.
- Line type drip tape, wall 0.15–0.20 mm (6–8 mil), Rivulis D1000
- 16 mm line waters up to 115 m evenly; on a 150 m row the last emitter gets 0.62 bar and the emitters’ flows differ by 21%
- 22 mm line up to 200 m; on a 150 m row the flows differ by 4%, and the row takes 500 L/h
- Choice 22 mm tape, or 16 mm tape fed from the middle of the row (75 m each way)
[The example’s numbers, and the series and sizes Perge stocks, await Perge’s check.]
How it is worked out
First the type. Tape (6–8 mil) does for one season on a level open field. If the line stays for several seasons, pick a thick wall: 0.45–0.76 mm for 2–3 seasons, 0.89–1.14 mm for 4 years or more. Use a pressure-compensating (PC) line on slopes over 2%, or where each plant in a pot or gutter must get the same water.
Then the longest row. The tool works down the line one step at a time, from one emitter to the next. At each step less water flows on; friction comes from the Darcy-Weisbach formula with the Blasius friction factor, and the slope adds or takes away pressure. This is the known Christiansen F factor method done step by step, so it can take the slope into account directly.
For a plain line, the limit is a 10% spread in flow between emitters, which is about a 19% spread in pressure. For a PC line, the limit is the pressure staying above 0.5 bar all along the row. The result is an estimate; the exact length comes from the maker’s own table.
Questions
How long can a drip line run?
It depends on the line size, emitter spacing, flow, pressure and slope. On level land, 16 mm tape with emitters every 30 cm at 1 L/h waters about 115 m evenly at 1 bar. A 22 mm line goes about 200 m in the same case. For longer rows, feed the line from the middle or use a pressure-compensating line.
What wall thickness should a dripline have?
Wall thickness is often given in mil; 1 mil is 0.0254 mm. For one season on an open field, 6–8 mil (0.15–0.20 mm) tape is enough. For 2–3 seasons pick 18–30 mil (0.45–0.76 mm), and for lines that stay for years in greenhouses and orchards, a thick wall of 35–45 mil (0.89–1.14 mm).
Drip tape or thick-wall dripline?
Tape has a thin wall and is light, and it usually lasts one season; open-field vegetable growers replace it every year. A thick-wall line lasts several seasons or even years, and suits greenhouses, vineyards and orchards. If you will roll the line up at the end of the season and lay it again, pick a thick wall.
When do I need a pressure-compensating dripline?
On slopes (steeper than about 2%), on very long rows, and in pots or gutters where each plant must get the same water. A PC emitter gives the same flow across a band of pressure, above about 0.5 bar for most models. On level, short rows you don’t need one.
How far apart should the emitters be?
It depends on the soil and the crop. Water spreads sideways little in sandy soil, so keep to 30 cm at most; in loam 30–50 cm, and in clay up to 60 cm. Closely planted vegetables often have 20–30 cm. In soilless growing, the spacing follows the pots or plants.
What pressure does a dripline work at?
Tape usually works at 0.5–1 bar and should not go over 1 bar. Thick-wall lines often run at about 1 bar; more pressure gives more flow. Pressure-compensating lines give the same flow from about 0.5 to 3.5 bar. Check the limits in each series’ own catalogue.