Irrigation Water Conveyance and Application Methods
Subtopic: Surface, sprinkler and micro irrigation methods
Question Statement:
In the emitter discharge equation $q = k \cdot H^x$, where $q$ is emitter flow rate and $H$ is operating pressure head, the discharge exponent for a fully pressure-compensating (PC) emitter is approximately:
Options:
(A) $x \approx 0.0$
(B) $x = 0.5$
(C) $x = 1.0$
(D) $x = 2.0$
Answer Key:
A
Step-by-Step Solution & Explanation
- Orifice/turbulent flow emitter: $x \approx 0.50$.
- Laminar flow (microtube): $x = 1.0$.
- Pressure-compensating (PC) emitter: Contains an elastomeric silicone diaphragm that flexes under increasing pressure to throttle the flow area, maintaining nearly constant discharge across a wide pressure range ($100 - 400\text{ kPa}$), meaning $x \approx 0.0$ ($q \approx \text{constant}$). Option A is correct.