Pipe Sizer - Pressure/Gravity

Pipe sizing app for water systems - both pressure and gravity. Supports S.I and I-P units.
The calculations are based on the Hazen-Williams equation for the pressure systems and the Manning's equation for the gravity systems.
User can pick from a variety of currently available pipe materials, more will be added in future updates based on users requests.
The app automatically recommends the most suitable pipe size for the required flow rate, based on friction rate and velocity limits set by the user.

Any feedback is welcome, and will be the basis for subsequent updates.