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Old 08-28-2012, 12:25 AM
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DanaMac DanaMac is offline
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Join Date: Mar 2002
Location: Somewhere in the state of CO
Posts: 13,166
Irrigation audit results

So, since it is a little slow for us, I took my guys to Ewing for a day, and we did some auditing. When they built the building, and did the landscaping, the manager had some say in the irrigation design. There is one section that is 30'x30', and it has 3 zones that water it, for this exact purpose of auditing.
Zone #1 has 4 rotors, all in the corners.
Zone #2 has spray heads spaced at 10' apart, standard RB nozzles.
Zone #3 has spray heads spaced at 15' apart, standard RB nozzles.
They water this 30x30 section, and nothing else.

I didn't worry about the rotors, as I wanted to compare some spray nozzles and MPs. We did 5 different audits. Once I enter the info into a spreadsheet, I'll post those as well. We used 48 catchments, and kept them all in the same places for all 5 audits. We calculated the audit two different ways - one was with all 48 cans, and a secondary audit with 40 cans, eliminating the 6 along the front edge of the direction of the wind, and 2 more along the next row. It wasn't bad, but it was maybe 5-8 mph at times. The measurements were fairly weak along that front row due to the wind.

Grass was a little long, and affected the 10' nozzles due to a lower angle. A few heads were a little crooked, but not too bad

Audit #1 - 10' spacing - standard RB nozzles - 35 psi at the heads - 5 minute run time
Initial audit = 35.5% DU
1.84" per square foot per hour (psfph)
This one stayed at about 35.5% even removing the 8 heads

Audit #2 - 10' spacing - Toro Precision nozzles - 42 psi - 5 minute run time
Initial audit = 20% DU
1.16" psfph
Secondary audit = 26% DU
1.25" psfph

Audit #3 - 15' spacing - standard RB nozzles - 28 psi - 5 minutes run time
48% DU
1.59 psfph
Secondary = 61.7% DU
1.75" psfph

Audit #4 - 15' spacing - Toro Precision nozzles - 32 psi - 5 minutes run time
Initial audit = 49% DU
0.97" psfph
Secondary = 69% DU
1.09" psfph

Audit #4 - 15' spacing - Hunter MP 2000 - 40 psi - 10 minutes run time
Initial audit = 69% DU
0.61" psfph
Secondary audit = 72.6% DU
0.65" psfph
**this is a little screwy because you wouldn't normally put MP 2000s 15' apart - but it's what we used**

I know the MP spacing was not right for the 2000s, but they were overwhelmingly more consistent. We can read it in the spec sheets all we want, but until we see them work in the field, it doesn't mean much. The consistency of the catchments was mind blowing, compared to the standard nozzles. I should have tried the 1000s, or even the 3000s with the half circles plugged off.

I did not do the calculations myself for all the audits, nor have I checked the math for all 5 audits. The three of us worked different ones. So when I enter into my spreadsheet, the numbers may be off somewhat. Just thought I would share our findings with you all.
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