In theory, Jabbo is correct but Tom knows exactly what I am talking about. You can't always adjust the nozzles to get the proper precipitation rate.
The Hunter manual lists precipitation rates (P.R) for each nozzle at 180 degrees (half arc) however we can calculate what the P.R. will be for any configuration using the following equation:
P.R.=(Flowrate*34650)/arc_angle*(radius*radius)
Using this equation we can calculate the following:
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GPM Radius(ft) %Adjustment 90 degree arc 180 degree arc 360 degree arc
--- ---------- ----------- ------------- -------------- --------------
.75 16 <font color="red"> 38% 0.5966</font id="red"> 0.2983 0.1491
1.0 19 16% 0.7955 0.3977 0.1987
1.5 22 0% 1.1932 <b>0.5966</b> 0.2983
2.0 25 -12% 1.5909 0.7955 0.3977
2.5 28 -21% 1.9886 0.9943 0.4972
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As Jabbo said, matching the GPM will effectively match the P.R. The above table shows the standard P.R for the 1.5gpm nozzle in a half arc configuration in bold. If I wanted to match the P.R. in a quarter arc, I would choose the nozzle with half the flow and adjust it to the same radius as the one I am using in a half arc configuration. In this case the .75-16ft nozzle will match the 1.5gpm-22 foot nozzle if stretched to 22 foot. If you look at the P.R in the first row under 90 degree arc, you will see it matches the value bolded under the 180 degree arc for the 1.5 nozzle. The problem is that the .75 gpm nozzle would have to be at 38% its design radius in order to achieve this. According to Hunter, they are adjustable to 25% of their rated radius. I don't know if 38% is even possible.
Placing them in separate zones sounds like a viable alternative, but choosing a different nozzle and adjusting the flow rate I think would be pushing it.
Thanks to you both for your input.