What is a metering pump used for?

Peristaltic pumps are used extensively as metering pumps in laboratory and medical applications but advances in materials technology have led to heavy duty pumps capable of dealing with highly viscous fluids, sludges and slurries in a wide range of industrial applications.
Reciprocating plunger pump is a kind of metering pump. It is a positive displacement pump, which achieves the purpose of conveying liquid through periodic changes in the working chamber. the mechanical energy of the prime mover is directly converted into pressure energy for the conveying liquid by the pump; the liquid volume of the pump only depends on the change value of the working chamber volume and The number of changes per unit time (frequency), and (theoretically) has nothing to do with discharge pressure.