An improved system, apparatus and method for injecting a chemical from a storage tank into a natural gas or liquefied petroleum gas pipeline at a flow-controlled injection rate is provided. The system, apparatus and method including a pair of positive-displacement pumps driven in substantially complementary fashion by a single driver, a controller controlling the driver, and each pump being fed from the storage tank and discharging chemical into the pipeline. The system, apparatus and method may also include a second pair of positive-displacement pumps having substantially similar displacement and operatively connected to the first pair of positive-displacement pumps, the first pair of positive-displacement pumps being driven in a substantially complementary fashion with the second pair of pumps by a single driver or a pair of drivers.