Chanaa dai,

Actually this type of equation applies to flow charecteristics in control valve (In Hydraulics). I think there are different types of valves based on the charecteristics as fast opening, linear, equal percentage etc(actually I also forgot all, polera khaaiyo) In this equation,

Y = 0.02 e ^ (3.91X)

X is opening i.e 0 for 'close' and 1 for 'fully open' while Y is percentage rate of flow i.e 1 means fluid flowing in full capacity.

But I think those type of curves apply everywhere (I dont know others).

And Loots,

I just found out the constants based upon your quation. You have the right equation and if you watch my datas, you can find equal %(almost 48%) increase (not increment) with the equal % increment( not increase), IMO.  

BTW, I dont know the mathematical defintition of this 'Equal percentage curve' as I said in my first post I just like to apply mathematics but never done correctly.

Parbatya