Flow Rate and Hydraulic Diameter
The chart above shows the relationship between flow rate and hydraulic diameter for three airless spray orifices with 24" spray patterns. The data shown are for a 1225, 1231 and 1239 spray tip respectively. The flow rates are for water at 20.15°C and 2000 psi.
You will notice that the hydraulic diameter measures noticeably less than the rated orifice size. This is discussed on the Cv Value page.
The slope of this curve fit is specific to the basic geometry of the spray orifice. In other words, spray tips with a different "V" angle, but similar hydraulic diameter will produce a different curve fit slope. Therefore, spray tips that are scaled one size to the next with similar ratios (i.e. Aspect Ratio) will follow a given trend.
It is the change in "V" angle that affects the aspect ratio of the orifice. In this case, the included "V" angle for a these 12XX spray tips is approximately 26.6° to 26.8°.
The included "V" angle of 1221 and 1223 spray tips is approximately 23.7° to 24.2°. The 1221 and 1223 would produce a different sensitivity relationship between flow rate and hydraulic diameter.
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