what would be the pressure of paint by an airless spray paint pump with15:1 ratio that was powered by 20psi of

Answer 1

The very instant its coming out of the nozzle , the pressure reaches a maximum of 300 psi.

This can be derived by the simple equation of 15 (from 15:1) and 20psi:

20 x 15= 300

But remember, there are many other factors involved such as friction and atmospheric pressure, so it will probably never actually reach 300 psi

Answer 2

That would be dependant upon the paint being used and the size of the spray nozzels and what setting is was set to. Most air based paint tools have adjustable spray patterns and adjustable outgoing pressures right at the point of release. Some are also hand controlled based on the movement of your fingers.

And on top of that you also have to consider the density and viscosity of the paint being used. It can be anything from an extremely watered down water paint to something thicker than the consistancy of tar.

So this is extremely application dependant.