Spray impact means the force of spray droplets hitting the target surface.
Solid stream jet nozzles have the strongest spray impact, and the wider the spray angle becomes or the larger the spray area becomes, the weaker the spray impact becomes.
Also, the impact decreases as the distance between the nozzles and the object becomes longer.
While each series of nozzles carefully designed in details can well enough withstand the specified pressures, depending on a system operation, water hammering may result in pressure increases of three to five times the spray pressure.
For use at high pressure, metal nozzles instead of plastic are recommended.
As the viscosity of the liquid increases, generally spray capacity and angle decrease and spray distribution diverges from the standard one. Also, spray pattern tends to be distorted.
Because viscous liquid increases the resistance inside a pipe towards a nozzle, the liquid pressure drop should be also taken into consideration.