And I feel like I've been here before.
Yes I feel like I've been here before.

("Deja Vu," by David Crosby of CSNY, 1970)

PTOA Segment 1: Starting to Focus on the Process Variable "Temperature"

PTOA Readers and Students reflected upon their fundamental understanding of "Temperature" as a measure of "hotness" and "coldness."

"Normal" and "Abnormal Temperatures" were shown to be relative terms defined more by what is expected in a given environment. Process Operators must know what temperatures to expect in the processing environment to be able to identify when an abnormal temperature exists.

The two most common temperature scales in the processing environment, Fahrenheit and Centigrade/Celsius, were introduced. The variance in the scales was inferred by examples. A link to an online Temperature Conversion resource was included in this PTOA segment. The resource is also listed in the PTOA Resources which can be accessed via the menu at the bottom of the PTOA Home Page.

PTOA Readers and Students learned that, as familiar and uncomplicated as it may appear, Temperature is an important process parameter that is monitored by outside Process Operators.

A picture of an outside Process Operator recording an assumed local temperature displayed on a local Temperature Indicator (TI) was shown. This picture provided a visual aid regarding how outside Process Operators monitor the processes that they are responsible for.

The concepts of "inside ambient temperature" and "outside ambient temperature" were introduced.

PTOA Students must understand that the outside ambient temperature cannot be manufactured. The outside ambient temperature is the temperature of the outside environment wherever the processing facility is located.

PTOA Students must understand that inside ambient temperatures can be manufactured; for example, air conditioners and room heaters maintain desired room temperatures.

Likewise, the temperature of the fluids flowing through processing pipes are manufactured by industrial-sized temperature-changing equipment.

The familiar concept of using energy to create desired temperatures provides the cornerstone of future PTOA Focus Studies.

 

PTOA Segment 2: Four Great Reasons to Monitor Temperature

The study of Temperature as an important Process Variable continued; PTOA Readers and Students were challenged to reflect upon how an outside Process Operator can use his/her knowledge of the process to maintain the desired operating temperature.

Four great reasons for monitoring temperatures were proposed:

PTOA Readers and Students discovered that non-desirable temperatures can impact yield, impair safe plant operations, and/or create an unwanted multi-phase mixture of gas/liquids/solids in the process stream. Local TIs could also be used to verify temperature readings observed in the control room.

By the conclusion of PTOA Segment 2, PTOA Readers and Students have learned that the variance of Temperature can significantly impact process operations. Hence, Temperature is an important parameter that must be monitored and controlled.These lessons support the upcoming statement made in PTOA Segment 7 that Temperature is one of the four major "process variables."

PTOA Segment 2 included a visual example of a local TI.

PTOA Segment 2 reminded PTOA Readers and Students that they are already familiar with changes of state (aka phase changes) and that changes of state occur due to changes in temperature.

 

PTOA Segment 3: Do You Know What I Mean?

This Instructional Jargon segment defined Process Temperature, Process Fluid, and Process Stream.

PTOA Readers and Students must understand these concepts and definitions before continuing to read PTOA segments.

PTOA Segment 3 also included definitions for "Fluid," "Vapor," and "Gas" and explained why the term "Gas" will be used....albeit, inaccurately... throughout the PTOA.

 

PTOA Segment 6: Every Picture Tells A Story, Don't It?

This initial introduction to Process Industry Schematics began with Piping and Instrumentation Diagrams (P&IDs).  P&IDs are both an original process design document and crucial resource for modern Process Operators to learn the purpose of the processing plant that they are accountable for.

PTOA Readers and Students identified local TIs on a P&ID excerpt.

The ISA P&ID symbol for a TI located at the bottom of a processing vessel was compared to a visual aid showing an actual TI connected to a real process vessel.

PTOA Readers and Students learned how to draw ISA P&ID symbols for local TIs and were introduced to ISA P&ID tag name nomenclature and ISA P&ID symbol keys.

The role of the International Society of Automation (formerly Instrument Society of America) was introduced as the gate-keeper for establishing and maintaining P&ID symbol nomenclature.

The other important process industry schematic for Operators...the Process Flow Diagram...was mentioned.

 

PTOA Segment 7: What Do P&IDs Have in Common with Crime Scenes?

The integrated studies of the Process Variable Temperature and the Process Industry Schematic known as a P&ID continued.

PTOA Readers and Students were shown a real P&ID excerpt. PTOA Readers and Students were challenged to pick out processing hints that P&ID symbols give to a P&ID reader.

The ISA P&ID rules for differentiating process stream lines from instrument connecting lines were introduced and illustrated on the P&ID excerpt. PTOA Readers and Students observed TIs connected to process equipment (a carbon filter) and a different TI connected to a process stream line.

The important role of arrowheads on P&ID process stream lines was introduced and illustrated. Arrowheads inform the P&ID reader which way the process stream is flowing.

A visual aid of an actual TI and its hardware connection to a thermowell (TW) was shown.

A comparison of two P&IDs illustrated how TIs are sometimes drawn with thermowells (TWs). PTOA Readers and Students became aware of how P&IDs can exhibit slight variances with ISA symbols.

Regardless of slight differences, PTOA Readers and Students learned that all instruments and equipment that appear on a P&ID have a purpose; no instrumentation or equipment is arbitrary. Every symbol on a P&ID gives a hint as to the role it plays in processing plant operations.

 

PTOA Segment 8: Give Me A "T" for "Temperature"

The integrated studies of the Process Variable Temperature and Process Industry Schematics continued; more ISA nomenclature for local Temperature instruments was introduced.

PTOA Readers and Students learned the procedure ISA established to assign tag names:

The first letter of a tag name is associated to whichever entity is being monitored and controlled; for example,  ISA has assigned "T" to mean "Temperature" when it appears as the leading letter in an instrument tag name.

The last letter in a tag name identifies what the instrument is, for example "I" for indicator and "W" for well.

Later in the segment, PTOA Readers and Students learned that a middle tag name letter represents the function of the instrument.

Building upon knowledge gained regarding local TIs and TWs, PTOA Readers and Students learned how the ISA P&ID symbols for local Temperature Indicating Controllers (TICs), local Temperature Transmitters (TTs), and local Temperature Recorders (TRs).

These ISA P&ID symbols were matched to real-world visual aids of local TICs and TRs so that PTOA Readers and Students could associate the symbols with the field instruments they represent.

 

PTOA Segment 9: All Board Operators are Control Freaks

The studies of the Process Variable Temperature and Process industry Schematics (P&IDs) continued to be integrated with a new focus on Process Industry Automation.

PTOA Readers and Students were introduced to the concept of pneumatic control and learned that a device called the pneumatic transmitter made it possible to centralize indicating, controlling, recording, and alarm functions into a control room.

The many benefits of centralizing automated control into a control room were mentioned. These benefits explained why process control evolved from having an outside Process Operator responsible for local instruments into creating Control Board Operators that use Control Board Panels to interface with a far away process plant.

Very important, the four main Process Variables were introduced.

The prior PTOA segments had prepared PTOA Readers and Students to accept that Temperature is a processing parameter which requires monitoring and controlling by Process Operators and Control Board Operators.

This now-familiar understanding of variances in Temperature was extended to include the need to monitor and control variances in process Pressure, Flowrate, and Level.

PTOA Students must understand that Process Operators and Control Board Operators spend their shifts...correction: spend their lives... monitoring and controlling process Temperatures, Pressures, Flowrates, and Levels.

 

©2015 PTOA Segment 00017
PTOA Deja Vu Review 1-1

 

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