Downstream chemical injectors are used to introduce chemicals or cleaning agents into the water downstream of the high-pressure pump. The chemicals are mixed with water after the water has been pressurized at the end of the pressure washing wand or gun. The "venturi" effect creates a vacuum to pull the chemical into the water stream as it flows through the injector. This allows the chemical to be applied at a lower pressure and flow rate to prevent damage to delicate surfaces or to ensure the proper amount of chemical is applied.
Downstream chemical injectors are commonly used in cleaning applications, such as in the cleaning of buildings, vehicles and outdoor surfaces, as well as in industrial settings where cleaning and disinfecting are required.