Characteristics of emitters under low pressure are essential for designing drip
irrigation systems. Low pressure data for drip emitters are not available from
manufacturers. A laboratory test was conducted to evaluate the performance of five
types of newly manufactured drip tapes, especially under a low pressure distribution
system. The five drip products that were tested were (i) Toro Drip in PC (PCS 1810-18-
100), (ii) T-Tape (TT15-1245-0100), (iii) Mister_LS (MLD-HDT100), (iv) Mister_PS
(MLD-1PC 25), and (v) Netafim (Techline CV 560 050). Drip tapes tested in this study
have design discharge rates of 4.00 L/hr @ 206.84 Kpa (1.06 gph @ 30 psi), 1.02 L/hr
@ 55.16 Kpa (0.27 gph @ 8 psi), 3.785 L/hr @ 172.37 Kpa (1.00 gph @ 25 psi), 3.785
L/hr @172.37 Kpa (1.00 gph @ 25 psi), and 0.984 L/hr @ 206.84 Kpa (0.26 gph @
20psi), respectively. All of them, except T-Tape, were pressure compensating (PC)
emitters; the T-Tape was non-pressure compensating (NPC). For all products, except
Toro, the emitter spacing was 0.305 m (12 inches) and for Toro, it was 0.46 m (18
inches). Mister_PS (MLD-1PC 25) was the point source (PS) emitter and all others were line source emitters. Drip products were tested with 15 different operating pressures
ranging from 5.97 KPa (0.87 psi) to 344.74 KPa (50.00 psi).
From an evaluation of 60 emitters from each product, the Toro brand showed an
average uniformity coefficient (UC) of 91.24 %, with a coefficient of variation (Cv) of
0.06, T-Tape drip products showed an average UC of 96.63 % with a Cv of 0.04, Mister_
LS showed an average UC of 93.12 % with a Cv of 0.08, Mister_PS showed an average
UC of 96.33 % with a Cv of 0.04, and Netafim showed an average UC of 97.92 % with a
Cv of 0.02. Flow rate vs. pressure head (Q-H) curves were also developed for each drip
emitter tested. From emitter exponent values it was observed that all of the pressure
compensating (PC) products behaved like NPC emitters at low pressures, although they
behaved like PC emitters under normal operating pressures. From statistical analysis, it
was determined that except for Netafim product, all other tested products were effective
under low operating pressures as were under high operating or recommended pressures.
Netafim product had no emission under low pressures.
Using the measured average emission rate and developed Q-H curves, the
distribution uniformities of all products except Netafim were calculated under low
pressure ranges of 5.97 KPa (0.87 psi) to 23.88 KPa (3.50 psi ) for different lengths of
laterals and under 0%, 1%, 2%
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2008-12-152 |
| Date | 15 January 2010 |
| Creators | Dutta, Deba P. |
| Contributors | Lesikar, Bruce J., Singh, Vijay P. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis |
| Format | application/pdf |
Page generated in 0.0022 seconds