Hydraulics & Pressure
Appliance Loss
Appliance loss is the pressure water gives up turning and splitting inside a device such as a gated wye, manifold, or monitor. Budget about 25 psi for an appliance in the lay.
Any hardware the water passes through costs pressure as the flow changes direction and divides. Treat an appliance like a short piece of extra hose in the pump discharge pressure: nozzle pressure, plus friction loss, plus the appliance.
Leave the appliance out of the calculation and every branch downstream of it runs weak. It is an easy line item to forget precisely because it is hardware rather than hose.
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