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## Homework Statement

A compressor is required to drive acetylene gas at 1.85 kg/s through a horizontal pipe, 68.7 m long. The maximum pressure that may be developed by the compressor is to be found, and gas pressure at the delivery end of the pipeline must be 470 kPa. The system is to operate isothermally at 20 degrees.

If a pipeline has a diameter of :0.0924 m, to what pressure must the gas be at the compressor if delivery pressure is to remain the same?

## Homework Equations

Data:

Molecular weight = 26 gram/mol

Gas Constant = 8.314 Jmol^(-1)K^(-1)

Fanning friction factor =0.002

I have attached the equation for horizontal, isothermal ideal gas flow in a pipe of constant cross section.

## The Attempt at a Solution

The answer is : 527.5 kPa

I understand the logic behind the question and the process that needs to be followed but I seem to have difficulty with the part where we need to use the 'iteration' method.

I have attached my working out. My question is with this iteration method when do we know when to stop? Sometimes in questions you find the pressure in your first attempt and in others in order to get the answer you need to do 3 steps. In this question it took me a 2 step process. Can someone please help me? I am preparing for exams and I need to use this method in questions like these but I don't know when to stop or when my answer is right. Is there a way of checking or knowing I am on the right track or how many steps I need to find the right answer?

Thanks for the all the help in advance.