Irrigation Sprinkler Uniformity
Christiansen CU and Distribution Uniformity from catch-can readings; pass/fail at 85% and 75%.
Example
You enter
- Catch volumes 100, 95, 98, 102, 105, 99, 97, 101
You get
- Mean 99.625
- Christiansen CU 97.6 %
- Distribution Uniformity 96.4 %
- Pass CU 85 Yes
- Pass DU 75 Yes
Checked against published worked examples from: Irrigation Association / ANSI / ASABE S436 catch-can identity.
Details, formula, and sources
Formula or tableChristiansen CU = 100 × (1 − Σ|x_i − mean| / (n × mean)). Distribution Uniformity DU = 100 × mean_lowest_quarter / mean_all. Pass / fail at CU 85 / DU 75.
Source and editionChristiansen 1942 paper by name; USDA NRCS National Engineering Handbook (NEH) Part 623 (Irrigation) by name.
Free accessUSDA NRCS NEH Part 623 free at nrcs.usda.gov.
What governsEstimate. AHJ and licensed professional govern.
API field namescatch_volumes, mean, CU, DU, pass_CU_85, pass_DU_75