Downstream Injectors: To avoid chemicals such as degreasers, soaps, disinfectants, and acids from damaging your pump a Downstream Injectors can be used instead of an Upstream Injector. A Downstream Injector is installed on the outlet of the pump whereas an Upstream Injector is installed on the inlet side of the pump. JE Adams Downstream Injectors can either be purchased with or without an adjustable knob and comes standard with a stainless steel ball. Our Acid Downstream Injectors are made with a ceramic ball (just order with an “A” in front of the Item #). JE Adams Downstream Injectors come in various GPM: 1-2, 2-3, 3-5, 5-8 with a standard 180 degree temperature rating and 3000 PSI.