Solving Pressure Problems


Guage pressure, or Pguage, doesn't take into account the atmospheric pressure in its readings. In chemical engineering, unless other wise stated, we want to use absolute pressure in calcualations. Converting from Pguage to Pabsolute is done using the following formula:

Pabs = Pguage + Patm

note: Let me re-emphasize, when pressure is initially given in guage, alway's first convert Pguage to Pabsolute before any other calculations.


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Upon studying this section, you should be familiar with the following:

    • How to use the Mass Balance Equation for reactive and unreactive chemical processes.
    • Be able identify a process as either a Batch or Continuous.
    • Write a Flow Chart with the information given in a problem statement.
    • Write a Table after writing a flow chart.
    • Use the principle of Degree's of Freedom to the extent only of writing boundries which will allow you to write the maximum number of equations.

A Material Balance Intro


Chemical processes are often very elaborate with many types of equipment used to obtain a desired product. Chemical engineer's are interested in many of the physical parameter's associated with each process, such as the flow rate of material the enters and leaves a peice of equipment, as well as several other parameters including the temperature and pressure of the material. Learning to keep track of the material and these physical properties in chemical processes is the objective of this course.

Here is an example of a two component process, the boxes represent equipment, and the arrowed lines represent streams of material.

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