Turn around ...Fate must have woke her
'Cause Lady Luck she was waiting outside the door.

I'm winning, I'm winning
I'm winning, I'm winning
I'm winning ... and I don't intend on losing again.

("Winning," by R. Ballard sung by Carlos Santana, 1981)

 

CROSSING THE PROCESS VARIABLE TEMPERATURE
FOCUS STUDY AREA FINISH LINE

YOU DID IT!

You have completed the fourth and final portion of the PTOA Process Variable Temperature Focus Study Area!

Stop what you're doing and take a victory lap right now!

Next time you are at the store, buy your favorite pint of ice cream and eat it all without sharing because YOU earned it!

 

Big Internet High Five with Your Mentor!

The very next PTOA Segment features a tidy summary of all  the competencies that you have acquired to this point so that you can be even more impressed with yourself.

 

Then the traditional Deja Vu Review of content and jargon used in the recently concluded PTOA Temperature Detection and Measurement Focus Study will follow.

Afterward ...once those reviews are completed ...

Totally new concepts related to the Process Variable Pressure will begin.

Wait! Don't stress out!

The PTOA Process Variable Pressure Focus Study Area is much shorter than the just-completed Process Variable Temperature Focus Study Area.

The PTOA Focus Study Areas dedicated to the Process Variable Flow and the Process Variable Level are also much shorter.

Your Mentor intentionally chose the PV Temperature to begin PTOA's guided self-study because everybody in the 93 countries that access the PTOA has a fundamental understanding of "Temperature."

 

Furthermore ...

There are many more types of process industry equipment used to change process stream temperatures than equipment used to change the other process variables.

Also ...

Optimizing the operation of temperature-changing equipment significantly impacts the profitability of the processing plant.

Process Operators that do not know how to optimize the operation of temperature-changing process industry equipment are wasting money!

 

LOOKING AT TEMPERATURE DETECTION AND MEASUREMENT IN THE REAR VIEW MIRROR

Just 118 PTOA Segments ago, PTOA Readers and Students who started reading the PTOA Segments in the intended sequential order began to aggregate a knowledge base built upon the new concepts and jargon related to the Process Variable Temperature.

Now they have a solid foundation for the highway that will propel them swiftly onward.

Temperature Detection and Measurement was the most recently concluded PTOA focus study related to the Process Variable Temperature.

Throughout that focus study, PTOA Readers and Students learned the following:

• The physical properties of Stuff/Matter/Mass can predictably change with temperature. These predictable changes in physical properties with temperature can be used by Mankind to infer a measured process temperature. Physical properties include  "volume changes" and "linear expansion rate" and "conductivity."
• Technology makes it possible to use "volume changes" (aka density changes) caused by temperature changes to measure process temperatures via liquid-in-glass thermometers and fluid-filled systems.
• Technology makes it possible to use the comparative "linear expansion rates" of two conjoined metal strips (a bimetallic strip) to measure temperature.
• Bimetallic strip technology can also be used for simple on-off temperature control and local temperature recording.
• Examples of the practical application and use of the Absolute Temperature scales °K and °R appeared in this focus study.
• Bourdon tubes function as transducers. A transducer is a device that changes one form of energy into another. The helically wound bourdon tube converts molecular movement sensed in a fluid-filled system into mechanical movement that is linked to a pointer and dial.
• Technology makes it possible to use the physical property of electrical "Conductivity" (and/or its inverse "Resistance") as it varies with temperature to generate an electrical output that can be amplified, converted, and eventually transmitted to a DCS device. Electrical temperature measurement devices include thermocouples, RTDs, and thermistors.
• Ohm's Law and the Electricity Transport Phenomenon rule the behavior of electrical circuits. Electrical circuitry is needed to convert RTD output and some thermistor output into standard signals that can be transmitted to a DCS device.
• Useful real-world linear or otherwise predictable relationships exist between changes in temperature and all the technologies used to measure temperature. Analyzing the slope of their graphed relationship reveals how steady the relationship is ... or isn't. PTOA Readers and Students can use the graph-analyzing tools that were incorporated in to this  focus study throughout the PTOA ... and life!
• Optical and IR pyrometry can closely approximate a temperature without any contact between the instrument and the surface having its temperature measured.
• Instrument Techie PTOA Readers and Students  learned how to determine an instrument's accuracy, repeatability, and reliability.
• Instrument Techie PTOA Readers and Students learned how measurement response lag can negatively impact the accuracy of temperature measurement.
• Instrument Techie PTOA Readers and Students learned the reason for and application of compensating bourdon tubes for fluid-filled temperature measurement and pressure measurement, cold junction compensation & extension wires for thermocouples, Wheatstone Bridges and excitation circuits for RTDs.

Whew! That's a lot of knowledge!

Your Mentor's vast processing experience predicts that PTOA Readers and Students who have persevered and completed the PTOA Segments in the intended sequential order currently possess more core competency about the Process Variable Temperature than the typical Process Operator currently possesses.

You better believe that Plant Owners want to employ Operators that know how to optimally operate the temperature-changing equipment!

Incidentally ...

Your Mentor is aware which PTOA Readers and Students have chosen not to read the PTOA Segments in the intended sequential order.

All's I can say is:

You Don't Know What You Don't Know!

So here's an easy link back to the PTOA Segment #1 entitled "How Hot is Hot?"

Your Mentor highly recommends that you take the time to become a Know-It-All like your PTOA peers.

 

SOMETHINGS YOU SHOULD HAVE THOUGHT ABOUT 

The introduction to the most recently completed focus study on Temperature Detection and Measurement posed some ponderable questions that you should have thought about while reading.

What does it mean in the real world to have a temperature detected, measured and indicated through a 'minor process line' connection?

 

The nearby photo was featured in PTOA Segments #108, #109, and #110 and is a great real-world example of what would appear as a "minor process line" drawn on a P&ID.

No process fluid flows through minor process lines.

Minor process lines on a P&ID simply show how the instruments and other auxiliary equipment are physically attached to the main equipment and vessels through which the main process streams being upgraded flow.

How does the TE/TI detect some kind of change in molecular movement, then convert the movement into a temperature measurement and also locally display the temperature in a way human beings can understand?

In PTOA Segment #103, Instrument Techie PTOA Readers and Students learned how a helically wound bourdon tube experiences mechanical movement (called displacement) when a change in temperature causes the expansion or contraction of the working fluid that is in the tube. The mechanical movement is linked to a pointer on a dial face that the Outside Process Operator can easily read.

PTOA Readers and Students are very familiar with the P&ID excerpt below which depicts a schematic of the flows entering, leaving, and bypassing shell and tube heat exchanger E-1004.

Every component of Temperature Control Loop 10045 that controls the tube outlet temperature was analyzed way back in PTOA Segment 16 entitled "Ever Evolving ISA Symbols."

What kind of physical connection does the P&ID excerpt illustrate exists between the shell side outlet process flow line and TE 10045?

What kind of signal is sent from TE 10045 to TIC 10045?

All PTOA Readers and Students will recognize that an electrical standard signal is shown transmitting from TE 10045 to TIC 10045 on the P&ID excerpt.

The electrical signal could be in some magnitude of amps or volts ...  that kind of detail is not discernible from the P&ID.

However the hints on the P&ID can be combined with the recently gained knowledge about temperature detection and measurement to deduce that TE 10045 must be a thermocouple or an RTD.

If the temperature sensor were an RTD, the real world connection (shown on the P&ID excerpt as a minor process line between the pipe and the ISA symbol TE 10045) could be the hardware shown from the nut of the "Fitting" to the "Connecting Head" in the below schematic.

How the heck can a TE detect a change in molecular movement and convert that movement into a measurement that is eventually conveyed as an electrical signal to the controller TIC 10045 located in the control room?

If the temperature sensor is a thermocouple, PTOA Readers and Students can apply what they have learned to infer that the measuring junction of the themocouple (aka hot junction) would transduce the molecular movement that results from a temperature change into a milliVolt signal that would be amplified and transmitted to the control room.

Instrument Techie PTOA Readers and Students could also Imagine that cold junction compensation and extension wires must have been properly selected and incorporated into the thermocouple installation to reduce the emfs that would otherwise cause inaccurate temperature measurements.

If TE 10045 is an RTD, PTOA Readers and Students know that the pure metal lead wires are impacted by  temperature changes which change their electrical resistance output which is in the non-standard signal form of ohms.

Instrument Techie PTOA Readers and Students understand that the RTD installation must include a Wheatstone Bridge to convert the ohms into a standard signal of volts ... and/or the bridge might include a galvanometer that converts the bridge output into the standard signal of milliAmps. An excitation current must also be supplied for the RTD to function.

Yes Indeedo!

PTOA  Readers and Students now competently understand how the temperature-measuring devices that are found all over the processing plant and drawn on P&IDs with ISA symbols are performing their respective temperature-measuring functions and yielding semi-accurate to accurate temperatures.

After studying the P&ID excerpt PTOA Readers and Students can conclude  that it is the shell side outlet temperature detected by TE 100045  that determines how much tube side inlet flow will be bypassed around E 1004 and allowed to flow through TV 10045.

In a future PTOA Instrumentation Focus Study Area, PTOA Readers and Students will learn that the process stream which flows through a control valve ... like the bypassed stream flowing through TV 10045 ...is the "manipulated process variable."

As is shown in the P&ID excerpt, the "manipulated process variable" can be a totally different process stream than the "measured process variable" ... the logically nick-named process stream that  interfaces with the detection and measuring device (TE 10045).

TAKE HOME MESSAGE: PTOA Readers and Students have completed the PTOA Focus Study on Temperature Detection and Measurement.

PTOA Readers and Students have also completed the PTOA Process Variable Temperature Focus Study Area.

Well done!

©2016 PTOA Segment 00119
PTOA Process Variable Temperature Focus Study Area
PTOA Process Industry Automation Focus Study Area

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