by means of the actuator fitted to the stroke mechanism. It is also possible to apply both variable speed and stroke variation to pump capacity control.

An interesting development is the water driven dosing pump which, as it is driven by the flow to be dosed provides proportional dosage to flow without the added complication of adding flow measurement systems.

The rotary motion of the motor is translated into a reciprocating movement by the drive mechanism or gearbox. In the case of sera pumps this is a robust, gear-oil filled gearbox giving exceptional reliability and economic operational performance. Both ‘modified-cam and slide-crank mechanisms are employed and their use is dependant on pump capacity. Usually slide-crank above 1.1kW motor size.
Pump capacities may be increased while retaining required system pressure by adding additional pump heads. This also has the potential to smooth delivery especially if an odd number of heads are utilised.

Typical applications can include one or more of the following, low flow rate, high accuracy, high system pressure, difficult media, corrosive, hazardous, high temperature, high viscosity or if it’s a slurry and also dosing may be controlled by computer, microprocessor, DCS, PLC or flow proportioning.

Due to the reciprocating action and two stage operation of dosing pumps the delivery is pulsating and additional equipment must be installed in order to obtain a consistent flow. Pulsation dampers fitted to the delivery of dosing pumps achieve this while also reducing pipe vibration and overall system component stress.