Following inferences about the flow rate can be made for a laminar flow in a horizontal pipe from the above analysis;

• It is directly proportional to the pressure drop
• It is inversely proportional to the viscosity
• It is inversely proportional to pipe length
• It is proportional to fourth power of pipe diameter

This flow properties are established experimentally by two independent scientists (G. Hagen and J. Poiseuille) and is known as "Hagen-Poiseuille" flow.
In case of non-horizontal pipes, the above expressions are slightly modified as;
                                          (16)
                                          (15)
                                          (16)
where is the angle made by the pipe with respect to horizontal and is the specific weight of the flowing fluid