This part of PS 799 specifies the construction of, and operational requirements and test methods for, differential pressure Venturi-type liquid additive injectors — a component of systems used to inject chemicals, including liquid fertilizers, liquid solutions of water-soluble fertilizers, acids, caustics, pesticides, herbicides and other liquid additives, into irrigation systems. This International Standard does not specify means of preventing backflow of liquid additives to potable water supply systems, the assembly of such means near to the Venturi injector being covered by water protection regulations.