apparatus and processes are provided for handling fluids in numerous industrial applications . materials addition devices , including venturi hoppers , and other eductor assemblies , are joined in compact , horizontal , and / or vertical configurations , with one or more shearing devices , including , high and low velocity shearing devices individually , as well as , a combination high and low velocity shearing device . pipe and valve configuration allow several alternate paths through or around such assemblies and devices , in alternate directions , including the option to backflow through the high velocity shearing device for the removal of obstructions . in the high velocity shearing devices provided , a special jet insert is provided , along with jet insert installation related apparatus , by which the jet insert is easily retained in , and removed from , the piping in the high velocity shearing device . various inlets into the materials addition devices , either singularly , or in combination allow optional paths for the entry of bulk materials , as well as , powdered polymers , liquid chemicals , and other materials , with a special tangential inlet used in some cases to work in combination with other inlets , to prevent vacuum dead spots during the process of introducing materials through inlet paths other than the traditional hopper throat . also provided is a detachable side plate adjacent the mixing chamber of the venturi hopper and / or eductor assemblies which , when removed , allows an additional port for the entry of bulk materials , and also allows quick inspection , servicing and / or removal of the venturi jet .