A $$400m$$ long horizontal pipe is to deliver $$900$$ kg of oil
$$\left( {S = 0.9,\,\,\upsilon = 0.0002{m^2}/s} \right)$$ per minute. If the head loss is not to exceed $$8$$ $$m$$ of oil, find the pipe diameter.

(Friction factor in laminar flow: $$f = 64/{R_e}$$)