Return to Homework 4 main page | Return to Homework page | Return to CM310 Homepage
  1. Please answer the following questions:
    1. What is the difference between schedule 40 and schedule 80 pipe?

      2. "Schedule 80 has a thicker wall and will withstand about twice the pressure of schedule 40 pipe. Both have the same outside diameter so that they will fit the same fittings," Geankolis 3rd edition p83
    2. At what value of Reynolds number does the transition from laminar to turbulent flow occur in pipes?

      3. Flow is laminar for Re < 2100 and turbulent for Re>4,000; between 2100 and 4000 is a transitional region where either type of flow could be seen, although in practical situations, the flow will be turbulent. (Geankoplis 3rd edition p89)
    3. What is the roughness of commercial steel?

      4. "The most common pipe, commercial steel, has a roughness of e=4.6 x 10-5 m." Geankoplis 3rd edition p89
    4. The chart on page 88 of Geankoplis 3rd edition gives values of Fanning friction factor versus Reynolds number for flow in a tube. We showed in class that dimensional analysis of the equations of change tells us that friction factor is only a function of Reynolds number (for flows without free surfaces). Is the analysis we carried out to arrive at that conclusion valid for the flow of gasses in pipes? Why or why not?  It's not really valid because we started with the equation of motion for an incompressible fluid, and gasses are not incompressible. Geankoplis reports, however, that experiments have shown that the friction factor methods hold if the density of the gas changes less than 10% in a flow of interest (p 91; 3rd edition).
Return to Homework 4 main page | Return to Homework page | Return to CM310 Homepage