Instruction Manual
P/N 20002315, Rev. A
February 2005
Micro Motion
®
Enhanced Density
Application
Theory, Configuration, and Use
Micro Motion
®
Enhanced Density
Application
Theory, Configuration, and Use
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Contents
Chapter 1 Before You Begin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Purpose of manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Terminology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Transmitter interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.4 Procedures described in this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter 2 Enhanced Density Theory and Background . . . . . . . . . . . . . . . . . . . . 3
2.1 About this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Enhanced density application overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3 Measuring density, specific gravity, and concentration . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3.1 Definition of density, specific gravity, and concentration . . . . . . . . . . . . . . 3
2.3.2 Effects of temperature on density, specific gravity, and concentration. . . . 4
2.3.3 Calculating concentration from density . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Defining a Micro Motion enhanced density curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.5 Enhanced density application example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Chapter 3 Loading a Standard or Custom Curve . . . . . . . . . . . . . . . . . . . . . . 13
3.1 About this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Standard and custom curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 Loading procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.3.1 Using ProLink II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.3.2 Using the display on Series 3000 4-wire transmitters . . . . . . . . . . . . . . . 16
3.3.3 Using the display on Series 3000 9-wire transmitters . . . . . . . . . . . . . . . 17
Chapter 4 Configuring a User-Defined Curve. . . . . . . . . . . . . . . . . . . . . . . . . 19
4.1 About this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 Measurement units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.3 Configuration steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.3.1 Using ProLink II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.3.2 Using the display on Series 3000 transmitters. . . . . . . . . . . . . . . . . . . . . 24
4.4 Curve fitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Chapter 5 Using an Enhanced Density Curve. . . . . . . . . . . . . . . . . . . . . . . . . 29
5.1 About this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.2 Specifying the active curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.2.1 Using ProLink II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.2.2 Using the display on Series 3000 transmitters. . . . . . . . . . . . . . . . . . . . . 30
5.3 Using enhanced density process variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.4 Modifying the curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.5 Saving a density curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Enhanced Density Application: Theory, Configuration, and Use i
Contents continued
Chapter 6 Advanced Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.1 About this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.2 Maximum order during curve fit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.3 Density curve trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.3.1 Offset trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.3.2 Slope and offset trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Appendix A Isotherm and Concentration Curve Ranges . . . . . . . . . . . . . . . . . . 37
A.1 About this appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
A.2 Fewer versus more points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
A.3 Fewer versus more points, and required ranges. . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Appendix B Configuration Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
B.1 About this appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
B.2 Electronic versus paper configuration records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
B.3 Derived variable: Density at reference temperature . . . . . . . . . . . . . . . . . . . . . . . . . 41
B.4 Derived variable: Specific gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
B.5 Derived variable: Mass Conc (Dens) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
B.6 Derived variable: Mass Conc (SG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
B.7 Derived variable: Volume Conc (Dens) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
B.8 Derived variable: Volume Conc (SG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
B.9 Derived variable: Conc (Density) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
B.10 Derived variable: Conc (SG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
ii Enhanced Density Application: Theory, Configuration, and Use
Chapter 1
Before You Begin
1.1 Purpose of manual
This manual is designed to provide two types of information: how the enhanced density application
works, and how to configure and use the enhanced density application.
1.2 Terminology
• Enhanced density curve – A three-dimensional surface that describes the relationship between
temperature, concentration, and density.
• Standard curves – A set of curves that are supplied by Micro Motion as part of the enhanced
density application, and are suitable for use in many processes. These curves are listed and
described in Chapter 3.
• Custom curve – A curve that has been built by Micro Motion according to customer
requirements.
• User-defined curve – A curve built by a customer, using the enhanced density application.
Theory and Background User-Defined CurvesStandard or Custom CurvesBefore You Begin
1.3 Transmitter interfaces
Depending on your transmitter, one or more of the following interfaces is available for the enhanced
density application:
• ProLink II – available for all transmitters except the Series 3000 9-wire
• PocketProLink – available for all transmitters except the Series 3000 9-wire
• The display (PPI) on the Series 3000 9-wire (ALTUS) transmitter
• The display (PPI) on the Series 3000 4-wire (MVD) transmitter
This manual shows the ProLink II interface and the Series 3000 display interfaces. The
PocketProLink interface is similar to the ProLink II interface.
1.4 Procedures described in this manual
There are two configuration procedures:
• If you purchased the standard curves or one or more custom curves, all you need to do is to
load the curve(s) into a transmitter slot. Instructions for loading a curve into a slot are provided
in Chapter 3.
• If you did not purchase standard or custom curves, you can configure your own curve(s), using
your own process data. Instructions for configuring a user-defined curve are provided in
Chapter 4.
Enhanced Density Application: Theory, Configuration, and Use 1
Before You Begin continued
After all curves have been loaded or defined, the active curve must be specified. Minor customization
of the curve is possible. The enhanced density application is now available for use in transmitter
configuration. Instructions for specifying the active curve, modifying a curve, and using a curve are
provided in Chapter 5.
The optional density curve trim is described in Chapter 6.
2 Enhanced Density Application: Theory, Configuration, and Use
Chapter 2
Enhanced Density Theory and Background
2.1 About this chapter
This chapter provides a conceptual overview of the relationship between density and concentration
and how concentration can be calculated from density. Additionally, this chapter discusses how this
calculation is implemented in the enhanced density application. Finally, this chapter provides an
example of enhanced density used in a real-world application.
Note: This chapter does not provide configuration instructions. For assistance with loading a
standard or custom curve provided by Micro Motion, see Chapter 3. For instructions on configuring a
user-defined curve, see Chapter 4.
2.2 Enhanced density application overview
Micro Motion sensors provide direct measurements of density, but not of concentration. The enhanced
density application calculates enhanced density variable,s such as concentration or density at
reference temperature, from density process data, appropriately compensated for temperature.
Theory and Background User-Defined CurvesStandard or Custom CurvesBefore You Begin
The derived variable, specified during configuration, controls the type of concentration measurement
that will be produced (see Section 2.3.1). Each derived variable allows the calculation of a subset of
enhanced density process variables (see Table 2-1). The available enhanced density process variables
can be used in process control, just as mass, volume, and other process variables are used. For
example, an event can be defined on an enhanced density process variable.
2.3 Measuring density, specific gravity, and concentration
Density, specific gravity, and concentration are central concepts in the enhanced density application.
This section defines these terms and describes the characteristics that are relevant to the enhanced
density application.
2.3.1 Definition of density, specific gravity, and concentration
Density is a measure of mass per unit volume. Density measurements apply to both pure substances
such as mercury or silver and compounds such as air and water. Typical density units include:
•kg/m
•g/cm
• lb (mass)/ft
• lb (mass)/gal
3
3
3
3
Enhanced Density Application: Theory, Configuration, and Use 3
Enhanced Density Theory and Background continued
Specific gravity is the ratio of two densities:
Density of Process Fluid at Reference Temperature T1
-------------------------------------------------------------------------------------------------------------------------------------------------------
Density of Reference Fluid at Reference Temperature T2
Water is typically used as the reference fluid. The T1 and T2 temperature values may be different.
Specific gravity has no units. The following reference temperature combinations are frequently used
to calculate specific gravity:
• SG20/4 – Process fluid at 20 °C, water at 4 °C (density = 1.0000 g/cm
• SG20/20 – Process fluid at 20 °C, water at 20 °C (density = 0.9982 g/cm
• SG60/60 – Process fluid at 60 °F, water at 60 °F (density = 0.9990 g/cm
Concentration describes the quantity of one substance in a compound in relation to the whole, for
example, the concentration of salt in salt water. Concentration is typically expressed as a percentage.
Concentration can be based on mass or volume:
-----------------------------------------------------------
Total Mass of Solution
Volume of Solute
-----------------------------------------------------------------
Total Volume of Solution
Mass of Solute
3
)
3
)
3
)
Typical concentration units include:
• Degrees Plato
• Degrees Balling
•Degrees Brix
• Degrees Baume (light or heavy)
• Degrees Twaddell
• %Solids/Mass
• %Solids/Volume
•Proof/Mass
• Proof/Volume
2.3.2 Effects of temperature on density, specific gravity, and concentration
Density always changes with temperature; as temperature increases, density decreases (for most
substances). See Figure 2-1. The amount of change is different for different substances.
4 Enhanced Density Application: Theory, Configuration, and Use
Enhanced Density Theory and Background continued
Figure 2-1 Density affected by temperature
Temperature = 4 °C Temperature = 25 °C
100 kilograms
100.0 liters
Density at 4
°C = 1000 kg/m
3
100 kilograms
100.3 liters
Density at 25
°C = 997 kg/m
3
Specific gravity does not vary with changing temperature, because it is defined at reference
temperatures.
When concentration is measured, the solute and the solvent typically have different responses to
temperature, that is, one expands more than the other as temperature increases. Therefore:
• Concentration values based on mass are not affected by temperature. This is the most common
type of concentration measurement. See Figure 2-2.
• Concentration values based on volume are affected by temperature. These concentration
measurements are rarely used, with the exception of the distilled spirits industry (proof is a
concentration measurement based on volume).
Figure 2-2 Concentration not affected by temperature
Theory and Background User-Defined CurvesStandard or Custom CurvesBefore You Begin
++
55 kg sucrose 45 kg water 100 kg sucrose solution
55 °Brix concentration
at all temperatures
Enhanced Density Application: Theory, Configuration, and Use 5
Enhanced Density Theory and Background continued
Because of these temperature effects, there is not a one-to-one relationship between density and
concentration (see Figure 2-3). A three-dimensional surface – concentration, temperature, and
density – is required. This three-dimensional surface is the enhanced density curve. Different process
fluids have different enhanced density curves. A typical enhanced density curve is shown in
Figure 2-4.
Figure 2-3 Relationship between density and concentration at two different temperatures
1.8
1.8
1.6
1.6
)
3
1.4
1.4
1.2
1.2
Density (g/cm
1.0
1
Temperature 1
Temp 1
Temperature 2
Temp 2
0.8
0.8
0 50 100
0 50 100
Figure 2-4 Example density curve
1.6
1.5
1.4
1.3
Y axis:
Density
1.2
1.1
Concentration (%)
100
20
60
Z axis:
Temperature
1.0
12
16
20
24
28
32
X axis:
Concentration
6 Enhanced Density Application: Theory, Configuration, and Use
36
40
44
48
52
Enhanced Density Theory and Background continued
2.3.3 Calculating concentration from density
There are two main steps in calculating concentration (see Figure 2-5):
1. Applying temperature correction to density process data. This step maps the current point on
the enhanced density surface to the equivalent point on the reference temperature isotherm,
producing a density-at-reference-temperature value.
2. Converting the corrected density value to a concentration value. Because all density values
have been corrected for temperature, any change in density must be a result of change in
composition of the process fluid, and a one-to-one conversion can be applied.
The enhanced density curve data stored in the transmitter contains the coefficients required to collapse
the surface to the density-at-reference-temperature curve, and to map that curve to the concentration
axis.
Figure 2-5 Enhanced density calculations
1.6
1.5
1.4
1.3
Y axis:
Density
1.2
1.1
1.0
X axis:
Concentration
12
16
20
24
28
32
36
40
44
48
52
100
Theory and Background User-Defined CurvesStandard or Custom CurvesBefore You Begin
Reference
temperature
isotherm
20
60
Z axis:
Temperature
2.4 Defining a Micro Motion enhanced density curve
This section provides a conceptual overview of the process of defining an enhanced density curve.
Specific configuration instructions are provided for standard or custom curves in Chapter 3, and for
user-defined curves in Chapter 4.
There are five steps involved in defining an enhanced density curve:
• Specifying the derived variable
• Specifying required reference values
• Defining the enhanced density surface
• Mapping density at reference temperature to concentration
• Curve fitting
Enhanced Density Application: Theory, Configuration, and Use 7
Enhanced Density Theory and Background continued
Step 1 Specifying the derived variable
The enhanced density application can calculate concentration using any of several different methods,
for example, mass concentration derived from reference density, or volume concentration derived
from specific gravity. The method used, and therefore the concentration measurement in effect, is
determined by the configured “derived variable.”
Depending on the specified derived variable, different enhanced density process variables are
available for use in process control. Table 2-1 lists the derived variables and the available process
variables for each derived variable. Be sure that the derived variable you choose will provide the
enhanced density process variables required by your application, and can be calculated from the data
that you have.
Note: All “net” process variables assume that the concentration data is based on percent. This
includes Net mass flow rate, Net volume flow rate, and the related totals and inventories. If you will
be using a “net” process variable for process measurement, ensure that your concentration values are
based on percent solids.
Table 2-1 Derived variables and available process variables
Available process variables
Derived variable – ProLink II label
and definition
Density @ Ref
Density at reference temperature
Mass/unit volume, corrected to a given
reference temperature
SG
Specific gravity
The ratio of the density of a process fluid at
a given temperature to the density of water
at a given temperature. The two given
temperature conditions do not need to be
the same
Mass Conc (Dens)
Mass concentration derived from reference
density
The percent mass of solute or of material
in suspension in the total solution, derived
from reference density
Mass Conc (SG)
Mass concentration derived from specific
gravity
The percent mass of solute or of material
in suspension in the total solution, derived
from specific gravity
Volume Conc (Dens)
Volume concentration derived from
reference density
The percent volume of solute or of material
in suspension in the total solution, derived
from reference density
Density at
reference
temperature
✓✓
✓✓✓
✓✓ ✓ ✓
✓✓✓✓ ✓
✓✓ ✓ ✓
Standard
volume
flow rate
Specific
gravity
Concentration Net
mass
flow rate
Net
volume
flow rate
8 Enhanced Density Application: Theory, Configuration, and Use
Enhanced Density Theory and Background continued
Table 2-1 Derived variables and available process variables (continued)
Available process variables
Derived variable – ProLink II label
and definition
Volume Conc (SG)
Volume concentration derived from specific
gravity
The percent volume of solute or of material
in suspension in the total solution, derived
from specific gravity
Conc (Dens)
Concentration derived from reference
density
The mass, volume, weight, or number of
moles of solute or of material in
suspension in proportion to the total
solution, derived from reference density
Conc (SG)
Concentration derived from specific gravity
The mass, volume, weight, or number of
moles of solute or of material in
suspension in proportion to the total
solution, derived from specific gravity
Density at
reference
temperature
✓✓✓✓ ✓
✓✓ ✓
✓✓✓✓
Standard
volume
flow rate
Specific
gravity
Concentration Net
mass
flow rate
Net
volume
flow rate
Theory and Background User-Defined CurvesStandard or Custom CurvesBefore You Begin
Step 2 Specifying required reference values
Depending on the derived variable, different reference values are required for the enhanced density
calculation. Table 2-2 lists and defines the reference values that may be required. Table 2-3 lists the
derived variables and the reference values that each requires.
Table 2-2 Reference value definitions
Reference value Definition
Reference temperature of process fluid The temperature to which density values will be corrected
Reference temperature of water The T2 temperature value to be used in calculating specific gravity
Reference density of water The density of water at the T2 reference temperature
Table 2-3 Derived variables and required reference values
Reference values
Reference temperature
Derived variable
Density @ Ref ✓
SG ✓✓✓
Mass Conc (Dens) ✓
Mass Conc (SG) ✓✓✓
Volume Conc (Dens) ✓
Volume Conc (SG) ✓✓✓
Conc (Dens) ✓
Conc (SG) ✓✓✓
of process fluid
Reference temperature
of water
Reference density of
water
Enhanced Density Application: Theory, Configuration, and Use 9
Enhanced Density Theory and Background continued
Step 3 Defining the enhanced density surface
The enhanced density surface provides the information required to perform temperature correction on
density process data, that is, to map process density values to density at reference temperature. To
define the enhanced density surface:
1. Specify 2 to 6 temperature values that will define the temperature isotherms
2. Specify 2 to 5 concentration values that will define the concentration curves
3. For each data point (intersection of a temperature isotherm with a concentration curve),
specify the density of the process fluid at the corresponding temperature and concentration.
For example, to define the enhanced density surface shown in Figure 2-6, with 6 temperature
isotherms and 5 concentration curves, you must specify the density of the process fluid at
Concentration A and Temperature 1, at Concentration A and Temperature 2, and so on through
Concentration E and Temperature 6.
Figure 2-6 Example density curve
Concentration curves A–E
1.6
1.5
1.4
1.3
Y axis:
Density
1.2
1.1
1.0
12
X axis:
Concentration
16
20
24
28
32
36
40
44
48
52
100
20
60
Z axis:
Temperature
Micro Motion recommends:
• Specifying the reference temperature as one of the temperature isotherms
• Selecting a range of temperature values that includes and is slightly larger than the range of
expected process temperatures
• Selecting a range of concentration values that includes and is slightly larger than the range of
expected process concentrations
Data for many process fluids can be obtained from published tables. Data for sodium chloride is
shown in Table 2-4.
Temperature
isotherms 1–6
10 Enhanced Density Application: Theory, Configuration, and Use
Enhanced Density Theory and Background continued
Table 2-4 Density of sodium chloride (NaCl) in water (H
Concentration % 0 °C 10 °C 25 °C 40 °C 60 °C 80 °C 100 °C
1 1.00747 1.00707 1.00409 0.99908 0.9900 0.9785 0.9651
2 1.01509 1.01442 1.01112 1.00593 0.9967 0.9852 0.9719
4 1.03038 1.02920 1.02530 1.01977 1.0103 0.9988 0.9855
8 1.06121 1.05907 1.05412 1.04798 1.0381 1.0264 1.0134
12 1.09244 1.08946 1.08365 1.07699 1.0667 1.0549 1.0420
16 1.12419 1.12056 1.11401 1.10688 1.0962 1.0842 1.0713
20 1.15663 1.15254 1.14533 1.13774 1.1268 1.1146 1.1017
24 1.18999 1.18557 1.17776 1.16971 1.1584 1.1463 1.1331
26 1.20709 1.20254 1.19443 1.18614 1.1747 1.1626 1.1492
O) at different temperatures and concentrations
2
Step 4 Mapping density at reference temperature to concentration
Note: If density at reference temperature or specific gravity was specified as the derived variable,
conversion to concentration is not required because these two variables are not measures of
concentration. Therefore, this step is omitted.
The enhanced density application must be able to map the density-at-reference-temperature curve to
concentration. This is accomplished by:
Theory and Background User-Defined CurvesStandard or Custom CurvesBefore You Begin
• Specifying 2 to 6 concentration values. Micro Motion recommends using the same values that
were used in Step 3.
• For each concentration value, specifying the corresponding density of the process fluid at
reference temperature.
Again, data for many process fluids can be obtained from published tables. For example, if the
process fluid is sodium chloride in water, and the specified reference temperature is 25 °C, the third
column of data in Table 2-4 provides the required values.
Step 5 Curve fitting
When data entry is complete, the transmitter automatically generates the enhanced density curve.
There are two measures of the goodness of a density curve:
• The outcome of the curve-fitting algorithm. Concentration will be calculated from the input
data only if the curve fit results are
Good. If the curve fit results are Poor or Fail, you must
repeat the process with modified data. Options include:
- Correcting inaccurately entered data
- Reconfiguring the curve using fewer temperature isotherms or concentration curves
If the curve fit results are
Empty, the curve-fitting calculation has not completed or has failed.
Wait for another minute, or reenter your data.
• The curve fit error. This value is based on the average error of the curve fit and does not
include any error values used to define the density curve, or any error in the density or
temperature measurements.
Note: Determination of the overall accuracy of the concentration calculation is complex and can be
laborious. If this information is required, contact Micro Motion customer service.
Enhanced Density Application: Theory, Configuration, and Use 11
Enhanced Density Theory and Background continued
The curve fit error is reported in the concentration unit that is currently active. It may be
represented as a value like the following:
In this example, if the concentration unit for the density curve is % solids, the average curve fit
error is 0.000084337 % solids.
2.5 Enhanced density application example
A plant uses a caustic cleaning solution (NaOH in H
To meet emission standards, the total concentration of NaOH in the wastewater cannot exceed 5%.
The concentration standard is defined on mass (rather than volume).
Without the enhanced density application
Based on testing, the cleaning solution is assumed to flow into the discharge tank at a concentration of
50%. Therefore, to comply with emission standards, one unit of the cleaning solution should be
diluted with 19 units of water. Periodically, samples are tested in the lab to monitor compliance.
This approach has the following drawbacks:
• The concentration of the cleaning solution may be different from the original sample.
• The concentration of the cleaning solution may vary beyond tolerances.
• Laboratory testing is slow and expensive, and may not catch serious variance: some batches
may be in violation of standards, while other batches contain more water than required, which
is unnecessary expense.
• Processing waste one batch at a time is inefficient.
• There is no provision for handling bad batches.
8.4337E-5
O) and discharges it into the city water system.
2
With the enhanced density application
A continuous blending process is implemented. A downstream flowmeter with the enhanced density
application is configured to measure concentration (mass). Through a PLC, the flowmeter controls an
upstream valve that controls the flow of water into the static mixer.
Using this technology:
• Any variation in the concentration of the cleaning solution flowing into the discharge tank is
compensated for, immediately and automatically.
• No laboratory testing is required.
• Batching is eliminated, along with bad batches.
12 Enhanced Density Application: Theory, Configuration, and Use
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