ABSTRACT
Metering is the continuous or batch injection of controlled volumes of reactants into process streams. Pumps used for metering are either special versions of reciprocating pumps or conventional pumps with special control. Metering control can be open loop, closed loop, or combined. When process flows can vary widely, controlled volume pumps require combined open and closed loop control to produce the required reactant flow range. Most controlled volume pumps are simplex, thus the flow pulsates significantly. System corrections and pulsation dampening, when necessary, are made in the same manner as those for larger reciprocating pumps. Conventional plunger or hydraulically actuated diaphragm pumps are used for “rough” metering.
