hi madhusmile
first you will know what is the diluition of polymer.
Polymers are so viscous so it's necessary to make a diluition.
For example if the polymer solution after diluition is 0.1% for dimensioning the pump the calcolus is:
700 gpm = 159 m3/h 5 ppm = 5 g/m3
153m3/h x 5g/m3 = 765 g/h
765/0.001 = 765000 g/h = 765 kg/h
If the density of solution is 1000 kg/m3:
the dosing pump will be 0.765 m3/h = 765 l/h = 3.36 gpm
that's all.
Bye
DocMax