Pressure and Flow: Two Basic Parameters of Irrigation System Design

Many customers ask "can my pump handle this?" or "why doesn't the tape at the far end spray far enough?" — the answers are hidden in two parameters: water pressure and flow rate. This article explains both clearly so you can judge whether your pump is up to the job.

1. Water Pressure: Know the Units and Conversions First

Three pressure units are common in irrigation: 1 MPa ≈ 10 kg/cm² ≈ 100 m head. Remember this conversion and reading pump nameplates or pressure gauges becomes easy.

Recommended working pressure for common products: micro spray tape 1 - 1.5 kg/cm² (0.1-0.15 MPa); drip generally operates at the 0.05-0.15 MPa level. Too much pressure will scatter the spray orifices and can even burst the tape, while too little pressure shrinks the spray width and starves the emitters of discharge.

2. Flow Rate: How Fast You Can Irrigate

Drip emitter discharge is 2-12 L/h; micro spray tape is estimated by the number and diameter of the holes. Total system flow ≈ simultaneously irrigated area × unit flow per mu (1 mu ≈ 667 m²), expressed as a formula:

Pump flow (m³/h) ≥ irrigated mu at the same time × required flow per mu (m³/h·mu)

Micro spray tape working simultaneously usually needs about 3-6 m³/h per mu, calculated by the number of tape lines and holes — give the pump a 10%-20% margin and don't run it at full load.

3. Line Losses: Where the Pressure Goes

Water meets resistance as it flows through the pipes: the longer the line, the smaller the diameter, and the more fittings and elbows, the greater the pressure loss. This is why "the head sprays far but the tail doesn't". What to do:

• Keep laying length within the recommended range (micro spray tape on level ground: 50-60 m per line);
• Choose a mainline one size larger to reduce losses along the way;
• For long distances or large areas, supply water in separate zones instead of running one line end to end.

4. Quick Pump Selection Calculation

Pump head ≥ elevation difference + line losses + working pressure at the end; flow ≥ total demand of the simultaneously irrigated area. Both conditions must be met at the same time. If you are unsure, send us a photo of the pump nameplate and we will check whether it can handle your area.