Chemistry (related to instrumentation)

Chemistry

http://www.ibiblio.org/kuphaldt/socratic/sinst/book/liii_1v36.pdf

See PDF Pages 241-298
(57 pages total)

Hart Communicator Test with RTD & Thermocouple

 Basic Concept of Hart PDF page 1024
http://www.ibiblio.org/kuphaldt/socratic/sinst/book/liii_1v36.pdf
(be willing to wait just a moment file size is large)

Ibid: PDF page 1435 about RTDs ,1443 about sensor connections
Ibid: PDF page 1447 about thermocouples, 1450 Types, 1469 about temp indicator connected to one.

Key Terms for Hart Communicator Test

Calibration

(1)A test during which known values of pressure are applied to the transducer and corresponding output readings are recorded under specified conditions.
(2)The matching of a pressure controller or indicator to the characteristics of a specific transducer. Most frequently done utilizing span resistor internal to the pressure transducer. Procedure is termed RCal.
(3)Adjustment of an instrument to standards of known accuracy and stability. (http://www.viatran.com/glossary#C)

Calibration

is used to perform such operations as

performing a sensor trim, D/A trim, and scaled D/A trim. (Hart 375 Manual PDF page 53)

Loop test

is used to set the output of the device at aspecified analog value, and may be used to test the integrity of the loop and the operation of indicators, recorders, or similar devices in the loop. (Hart 375 Manual PDF page 53)

Reranging

A procedure allowing the modifications of configuration values and parameters that change the transmitter 4-20 mA output settings in response to input pressure readings.(http://www.viatran.com/glossary#R)

Sensor Trim

A digital trim procedure which permits the adjustment of a digital process variable to a precisely known input pressure. Zero Trim and Full Trim are the two Sensor Trim functions.(http://www.viatran.com/glossary#S)


Questions:

• What does the Dry Block Calibrator do?  ___ , ___ 

My Answer???:  Heat, Cool (Brief Reference see top of page 2)

• How does the RTD calibrator Simulate the Temperature scale?

• How does the thermocouple calibrator change the temperature scale setting? (Ex: betwxt K, J , T )  

My answer:  By pressing the store button

Derrick TassinOctober 6, 2013 at 12:58 PM

To change the temperature scale setting for the thermocouple calibrator, on the service manuel it says to use the dip switches, and to change t/c type to use the scroll button.

____ is always the negative ____

My answer: (concerning thermocouples)
the red , wire is always negative

Pressure & Level Class Labs

 About the Differential Pressure Transmitter PDF Page 1261
 http://www.ibiblio.org/kuphaldt/socratic/sinst/book/liii_1v36.pdf

Hart 275 Manual ***Link

Rosemount 3051  Reference Manual

 

 

Rerange (pfd p. 54) The Range Values command sets each of the lower and upper range analog

values (4 and 20 mA points and 1 and 5 Vdc points) to a pressure. The lower

range point represents 0% of range and the upper range point represents

100% of range. In practice, the transmitter range values may be changed as

often as necessary to reflect changing process requirements. For a complete

listing of Range & Sensor limits, refer to “Range and Sensor Limits” on

page A-4.

NOTE

Transmitters are shipped from Emerson Process Management fully calibrated

per request or by the factory default of full scale (zero to upper range limit).

NOTE

Regardless of the range points, the 3051 will measure and report all readings

within the digital limits of the sensor. For example, if the 4 and 20 mA points

are set to 0 and 10 inH2O, and the transmitter detects a pressure of 25 inH2O,

it digitally outputs the 25 inH2O reading and a 250% of range reading.

 

P.56

Reranging using the Field Communicator and applied pressure is a way of

reranging the transmitter when specific 4 and 20 mA points (1 and 5 Vdc

points) are not calculated.

 

Sensor Trim

P. 80

Sensor Trim Overview

Trim the sensor using either sensor or zero trim functions. Trim functions vary

in complexity and are application-dependent. Both trim functions alter the

transmitter’s interpretation of the input signal.

…
Sensor trim is a two-point sensor calibration where two end-point pressures

are applied, and all output is linearized between them. Always adjust the low

trim value first to establish the correct offset. Adjustment of the high trim value

provides a slope correction to the characterization curve based on the low

trim value. The trim values allow you to optimize performance over your

specified measuring range at the calibration temperature.

 

See next page--à

 

 

ANALOG OUTPUT TRIM   --------(Digital-to-Analog Trim)

p. 77

The Analog Output Trim commands allow you to adjust the transmitter’s

current output at the 4 and 20 mA (1 and 5 Vdc) points to match the plant

standards. This command adjusts the digital to analog signal conversion.

Zero Trim 275 Hart Communicator--- 

HART sensor trim upper 275

HART communicator connection points Communicator loop resistance video

•  Read this PDF on JouleDeadweight Tester
• *operating instructions start on p. 20

•  Blog post

RTD/ Thermocouple Calibration

 Click link below to view calibration procedure

Hart 275 Communicator Manual *Link

• Generic online menu tree (PDF page 29)

Hart 375 Communicator Manual  *Link

• Glossary PDF Page 105

https://docs.google.com/file/d/0B4VZxTBlmecNOVJ3eFh2QVBJQWs/edit?usp=sharing

Note** Model 3144 TT navigation diagram to access snsr trim select snsr trim, but on

Model 644 TT select Scaled D/A Trim to get to snsr trim (sensor trim)

picture: Below attachment for  Model 3144 Temperature Transmitter.

250 Ohm Resistor attached to negative terminal to power supply

terms

Thermistor- Small enough to fit on a dime this is a special kind of semiconductor changes electrical resistance with temperature changes.
 With increased sensitivity it detects small temperature changes more than an RTD can.

Sensitivity- a device's ability to detect changes in a variable.
The more resolution a device has within a variable range the more that the change in the variable can be detected.

Thermocouple- an arrangement of 2 dissimilar metals in the form of wires joined together at both ends. It detects temperature by generating an electrical voltage.

The difference in voltage measurement of the variable or hot junction to that of the reference or cold junction determines a voltage from which a corresponding known temperature can be found on a chart specifically for that said thermocouple. If millivoltage is between 2 reference temperatures a
calculation*  is performed to determine the actual temperature

Calucation involves *Span Math to convert milivoltage to temperature

Pressure and Level class

PDF of Some Formulas we came up with

These are to convert from psig to psia & vice versa as well as determining inches of water from those.

Mass Flow Rate Problem

 PDF of Problem

Video
Remember to convert degree Celcius to degree F