Question

The average discharge, operating pressure and emitter constant of a drip emitter are \(4\,\text{L h}^{-1}\), \(110\,\text{kPa}\) and \(0.3\), respectively. The type of emitter is

• A. orifice
• B. long path
• C. pressure compensating
• D. disc

Hint:

Remember the rule of thumb: \(x\!\approx\!1\) (laminar), \(x\!\approx\!0.5\) (turbulent/orifice), \(x\!\approx\!0\) (pressure-compensating). Smaller \(x\) means discharge changes little with pressure.

Answer 1

The Correct Option is C

Step 1: Use the emitter exponent for classification.
Most emitters obey \(q=k\,P^{x}\), where \(x\) (emitter exponent) indicates sensitivity of discharge to pressure. Typical ranges used in design manuals are: \[ \begin{aligned} & x \approx 1.0 &&\text{laminar/capillary (long-path laminar)}
& x \approx 0.45\text{–}0.55 &&\text{turbulent/orifice/vortex/disc}
& x \approx 0\text{–}0.1 &&\text{pressure-compensating (nearly constant }q) \end{aligned} \] An exponent \(\,x=0.3\,\) indicates strong pressure compensation (much lower than the turbulent/orifice value).

Step 2: Match with given data.
Given \(x=0.3\) and a nominal discharge \(q=4~\text{L h}^{-1}\) at a typical operating pressure \(P=110~\text{kPa}\) — these are characteristic of commercially available pressure-compensating drippers (commonly rated 4 L h\(^{-1}\) with low \(x\)).

Final Answer:
\[ \boxed{\text{Pressure compensating (Option C)}} \]