A perfectly insulated double pipe heat exchanger is operating at steady state. Saturated steam enters the inner pipe at $100^{\circ}C$ and leaves as saturated water at $100 ^{\circ}C$. Cooling water enters the outer pipe at $75^{\circ}C$ and exits at $95^{\circ}C$. The overall heat transfer coefficient is $1\: kW\: m^{-2}\:K^{-1}$ and the heat transfer area is $1\:m^{2}$. The average specific heat capacity of water at constant pressure is $4.2\:kJ\: kg^{-1}\:K^{-1}$. The required cooling water flow rate is ______________ $\text{kg}$ $s^{-1}$ (rounded off to two decimal places).