Process Control Tutorial

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Introduction

What is Process Control?

Process Control consists of the systems and tools used to ensure that processes are well defined, performed correctly, and maintained so that the completed product conforms to established requirements. 

Process Control is the active changing of the process based on the results of process monitoring. Once the process monitoring tools have detected an out-of-control situation, the person responsible for the process makes a change to bring the process back into control.

All process control configurations, whether manual, automatic, or computer-based, have three essential elements: a measurement; a control strategy; an element for implementing the control action.

 

The Process Control objective is to maintain the output of a specific process within a desired range. For example, to control the temperature of a continuous stirred-tank reactor.

Figure 1: Example to control the temperature of a continuous stirred-tank reactor by a sensor.

Process control is extensively used in industry and enables mass production of consistent products from continuously operated processes such as oil refining, paper manufacturing, chemicals, power plants and many others. Process control enables automation, by which a staff of operating personnel can operate a complex process from a central control room.

Figure 2: NASA's Shuttle Flight Control Room in Houston, Texas

What is a process?

Click on each green spot and know more about processes:

How is Process Control seen by NASA's Process Control Focus Group (PCFG)?

Process Control was utilized as an essential element for managing risk to ensure the safety and reliability of the Space Shuttle Program. It was recognized that strict process control practices aided in the prevention process escapes that may result in or contribute to in-flight anomalies, mishaps, incidents and nonconformances.

The PCFG developed free products for the suppliers of the Space Shuttle Program. These products stressed the importance of process control. A program where a great number of parts must function under extreme environments, process control must be rigorously applied to a large number of parts suppliers that employ a variety of manufacturing process. If control was not appropriately applied, there was a risk of failure.

According to the PCFG, "the Space Shuttle Process Control Management Plan defined the minimum requirements for process control related to flight hardware and critical ground support equipment for the Space Shuttle Program prime contractors."

The following standards were developed to exert process control. They include some examples of the engineering tools and techniques.