Industrial Gas Pipe Flow Modeling

I need accurate pipe-flow calculations to finalise an industrial gas-distribution system that is now at the layout stage. The job centres on a single line (straight runs, a handful of elbows and valves)... (Budget: $3000 - $5000 SGD, Jobs: Computational Fluid Dynamics, Electrical Engineering, Engineering, Finite Element Analysis, Mechanical Engineering, Piping, Process Engineering, Simulation, Thermodynamics)