*pp = paragraph
PDF Look on page 49
Image of Loop sheet with Some analytical symbols
Piping & Instrumentation Diagram (About on wikipedia.org)
Interpreting Instrument Diagram Symbols
Definitions: Conductivity, Conductance, Resistivity, Resistance,Cell Constant, PH, ORP
- Conductance - A measure of the ability of a circuit to pass current.(pp* 1.03)
- Conductivity- Of a substance is the conductance of a unit length & cross-sectional area of that substance.(pp 1.04)
- Resistance - a measure of the ability of an electrical circuit to oppose current flow. (pp 1.03)
How is the Cell constant is determined & what the cell constant for conductivity instrument designates.
Dissociation : the miracle property of water
Know how these are made: Conductivity Probe, PH probe, ORP probe
Relative to how each are constructed
Know Maximum Temperature & Pressure limits for conductivity, PH, & ORP probes.
Know the unit of measurement for conductivity, PH & ORP
Have a good understanding of What Grab sampling is
Should be able to follow the flow through the sample conditioning systems shown in the first 2 chapters of your analytical book
will have on test
-Pressure Reduction Sample conditioning system
-Temperature Reduction Sample conditioning system
- Calibration inhancement sample conditioning systems
Know the 'innereds' of conductivity relative to the two basic conductivity _probe assemblies_ you're going to find.
What probe should not be used in metal piping?
Ans: Conductive Probe
Which one is the Inductive Probe?
the one with a hole in the middle. why does it have the hole?
Ans: Inducing current flow in the center out
Through the use of 2 coils the primary coil and the secondary coil. The 2nd coil measures the induced current caused by the Primary coil.
what in the water is giving a path for the current?
Ans: ions
The current flow (in the loop of the inductive probe) will only be as much as what?
Ans: As the number of ions you find in it.
In conductivity the path for current to flow is ionic.
In Pure water what do we do? What is the attempt made to purify water?
To remove contamination at the ionic level (not just the visual level).
- Until we remove the dissolved ion contamination the water may appear pure, but it is not pure.
If an analytical system removes the sample from the process what type of system would we call that?
Vs. the type of system we would tag if we placed the probe directly into the process.
- 2 types are?
- Incitu- probe directly in the process,
- Extractive-the process must be conditioned before being presented to the probe
Retractable probe (placed in process) process is below the limits set by the manufacturer of the probe is referred to as an
incitu analysis the probe is directly in the process.
If we have sample conditioning system where we have to do pressure or remove heat or filter that is refered to as an
extractive analytical operation Brought to instrument for analysis.
Definitions for temperature labs on 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)
Calibrating the transmitter increases the measurement precision by allowing
corrections to be made to the factory-stored characterization curve by digitally
altering the transmitter’s interpretation of the sensor input.
To understand calibration, it is necessary to understand that smart
transmitters operate differently from analog transmitters. An important
difference is that smart transmitters are factory-characterized, meaning that
they are shipped with a standard sensor curve stored in the transmitter
firmware. In operation, the transmitter uses this information to produce a
process variable output, in engineering units, dependent on the sensor input.
(PDF of 644 Smart Temp TRansmitter page47)
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)
Loop test verifies the output of the transmitter, the integrity of the
loop, and the operations of any recorders or similar devices installed in
the loop. (PDF of 644 Smart Temp TRansmitter page41)
- 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)
Rerange
Reranging the transmitter sets the measurement range to the limits of
expected readings. Setting the measurement range to the limits of expected
readings maximizes transmitter performance; the transmitter is most accurate
when operated within the expected temperature range for your application.
(PDF of 644 Smart Temp TRansmitter page44)
- 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)
Sensor Input Trim
Perform a sensor trim if the transmitters digital value for the primary
variable does not match the plant’s standard calibration equipment. The
sensor trim function calibrates the sensor to the transmitter in temperature
units or raw units. Unless your site-standard input source is
NIST-traceable, the trim functions will not maintain the NIST-traceability of
the system.
The Sensor Input Trim command allows the transmitter’s interpretation of
the input signal to be digitally altered (see Figure 3-5). The sensor
reference command trims, in engineering (F, °C, °R, K) or raw (Ω, mV)
units, the combined sensor and transmitter system to a site standard using
a known temperature source. Sensor trimming is suitable for validation
procedures or for applications that require calibrating the sensor and
transmitter together. (PDF of 644 Smart Temp TRansmitter page48)
- Know the difference between your reference & measurement electrodes. How they are constructed & what their purpose is.(there is a purpose for each one)
- Probes are an asssembly with electrodes & what other device does each probe assembly consist of ?
- What other device does it have to contain when measure Ph or ORP conductivity?
- Ans. RTD (resistance temperature detector)
Need to know what the PH scale is 0-14. What portion of the PH scale is Neutral, Acidic, and Basic?
Buffers / standards for determination are always 4,7,& 10
You use two for 2-point sampling (not as reliable as 1-point grab sampling <---resist that as much as you can - great as a means of checking the machine, but stinks as a means of checking Ph & ORP not the path you want to take)
3 PH buffers you want to calibrate your electrode
3 conditions you are likely to find
- Acid stream (always below 7) use a 4,7 buffer
- Caustic or Basic Stream (always above 7) use 7,10 buffer
- Neutralization Process where ph runs both above & below 7, where 7 is the stated goal in neutralization. In this instance use the 4& 10 buffer (typically for calibration)
Be able to answer following Qs:
- Liquids with an oxidizing potential have a(n) ___ of electrons & a ____ polarity.
- A. Excess, Negative
- B. Excess, Positive
- C. Shortage, Negative
- D. Shortage, Positive
- What is the solution for the reference electrode for the Ph or ORP probe?
- Ans: KCl (Potassium Chloride)
Span Math Sheet on Test
Loop Sheet on Test ----------Analytical Loop Sheet (more complicated loopsheet )
Image of Loop sheet with Some analytical symbols example found
Interpreting Instrument Diagram Symbols
Piping & Instrumentation Diagram (About on wikipedia.org)
Where can the definitions can be found from labs
in 644 & 3144 Temp. manuals online.
Everything On Review
Questions To turn in on test day
CHAPTER ONE
- What is the unit of measurement for conductance?
Siemens Symbolized with G
- Why does pure water have low conductivity?
low ion concentration
- When you increase the temperature of a liquid,
what happens to its conductivity?
it increases
- No direct contact is necessary between the coils
and the solution in what type of probe?
Inductive Probe
- What kind of contact with hazardous calibration
liquids should you always avoid?
Avoid Skin or eye contact
- How can you check a probe’s accuracy against
off-line instruments?
- What type of probe should you never install in a steel pipe?
Conductive Probe
- In a conductivity probe, what must always be
completely covered by the process liquid?
- What should you always follow to install or
remove a probe?
- What monitors the exposure of a worker to a
particular gas?
CHAPTER 2
- What is a measure of the number of hydrogen ions
in a process liquid?
- What is the pH of a neutral solution?
- What is the unit of ORP measurement?
- What are the two electrodes that make up pH and
ORP probes?
- What must you use for calibration if the process
liquid chemicals cannot be duplicated in a buffer solution?
- What device indicates when filters need to be
replaced or backflushed?
- In a pH or ORP installation, must the pressure at
the outlet be higher or lower than the inlet pressure?
- What is the maximum temperature most pH or ORP
electrodes can withstand?
- What device is used in a pH or ORP installation
to lower the temperature of the process liquid to an acceptable level?
- What kind of electrode can be installed or removed
without shutting down the process system?
