Pressure in parallel pipes

If the length of the 2 branches differ friction in that branch will be more. As water always follow the path of least resistance the flow in the shorter pipe will be higher to balance the pressures at the branching point.

The cross sectional area of two 1" pipes is much less than that of a single 2". There will be a pressure drop at the fork and through the nozzles. Standard piping specs will allow you to calculate the drop due to viscous effects, diameter, length, and flow rate are the key factors. The max flow of 30 gpm is set in the forks and nozzles. If your question is will the nozzles cavitate the answer is if you don't want them to they will and if you do want them to they won't.

Best wishes,

Mr. Gee

That's right, the cross sectional area of 1" is only one forth (not one half) of 2" dia pipe. This means the total areas after the branch-off is only half of up stream. So a huge velocity rise there at branch-off and further velocity rise at the nozzles where possible reduction of cross sectional areas.

Quantity = Area X Velocity, holds good only for a range.