if i have Ms Pipe of dia 1900mm and another with 800 mm. i need to join them with a tapper. how much length of taper it could be needed?? and give the formula also.
I don't have TPF.
This is a general and it's a try. You have insufficient condition to explain the length of taper part.
The image goes here.
The amount of taper depends on how/what flows through the pipes. I recall that a total taper of 15° or less will prevent turbulence in air flowing through a duct.