Chemtrac LCA-1, LCA-3, LCA-2 Operation Manual
OPERATIONS MANUAL
Models: LCA-1, LCA-2, LCA-3
Laboratory Charge Analyzer
Revised 05/01/2017
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TABLE OF CONTENTS
Contents
1. Product Description .............................................................................................................................. 5
1.1 General .......................................................................................................................................... 5
1.2 Applications ................................................................................................................................... 6
1.2.1 Determining Coagulant Dosage ............................................................................................ 6
1.2.2 Determining Caustic Dosage ................................................................................................ 6
1.2.3 Determining Polymer Dosage ............................................................................................... 6
1.2.4 Charge Demand .................................................................................................................... 6
1.2.5 Determination of Isoelectric Point ......................................................................................... 6
1.2.6 Other Applications ................................................................................................................. 6
1.3 Model Designation ........................................................................................................................ 6
1.4 Included Items ............................................................................................................................... 6
1.5 Options .......................................................................................................................................... 6
1.5.1 pH and Temperature ............................................................................................................. 6
1.5.2 Roll Away Case ..................................................................................................................... 6
1.6 Specifications ................................................................................................................................ 7
1.7 LCA Components .......................................................................................................................... 8
1.7.1 LCD Display & Menu Keypad ................................................................................................ 8
1.7.2 Stand Release (Raise & Lowers Stand) ............................................................................... 9
1.7.3 Probe and Piston ................................................................................................................... 9
1.7.4 Beaker (Optional) .................................................................................................................. 9
1.7.5 Magnetic Stirrer and Stir Bar ................................................................................................. 9
1.7.6 Coagulant / Polymer Titrant Container .................................................................................. 9
1.7.7 Acid / Base Titrant Container ................................................................................................ 9
1.7.8 Coagulant / Polymer Titrant Pump ........................................................................................ 9
1.7.9 Acid / Base Titrant Pump ...................................................................................................... 9
1.7.10 pH electrode and Temp probe .............................................................................................. 9
2. User Menu .......................................................................................................................................... 10
2.1 Titration Setup (LCA-2 & LCA-3 Only) ........................................................................................ 10
2.1.1 Sample Volume ................................................................................................................... 10
2.1.2 Charge Titration................................................................................................................... 10
2.1.3 pH Titration (LCA-3 Only) .................................................................................................... 11
2.2 Calibration ................................................................................................................................... 12
3. Operation ............................................................................................................................................ 13
3.1 Water Treatment – Determining Optimum Coagulant Dosage ................................................... 13
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3.1.1 Introduction .......................................................................................................................... 13
3.2 Preparation for Sample Testing .................................................................................................. 17
3.2.1 Collect Raw Water Sample ................................................................................................. 17
3.2.2 Prepare Sample for Testing ................................................................................................ 18
3.2.3 Positioning Sensor into Sample .......................................................................................... 18
3.2.4 Sensor Conditioning & Stabilization .................................................................................... 19
3.2.5 pH Measurement and Adjustment ....................................................................................... 19
3.2.6 Titration Procedure .............................................................................................................. 20
4. Maintenance ....................................................................................................................................... 22
4.1 Signal Health Readout ................................................................................................................ 22
4.2 LCA Sensor Cleaning .................................................................................................................. 22
4.2.1 Cleaning Procedure ............................................................................................................ 22
4.2.2 Use of Approved Cleaners .................................................................................................. 23
4.2.3 List of Approved Cleaners For LCA Sensor ........................................................................ 23
4.3 Titrant Pump Cleaning / Maintenance ......................................................................................... 24
4.4 pH Probe Cleaning ...................................................................................................................... 24
4.5 Storage ........................................................................................................................................ 25
4.5.1 LCA Storage ........................................................................................................................ 25
4.5.2 pH Probe Storage................................................................................................................ 25
4.6 LCA Sensor Check and Calibration ............................................................................................ 25
4.6.1 Basic Function Test ............................................................................................................. 25
4.6.2 Test Procedure Using Verification Solutions ...................................................................... 25
4.7 Application Questionnaire ........................................................................................................... 27
Figure 1 - Double Layer Charge ................................................................................................................... 5
Figure 2 - Streaming Current Sensor ............................................................................................................ 5
Figure 3 – LCA Components ........................................................................................................................ 8
Figure 4 – Display & Menu Keypad .............................................................................................................. 8
Figure 5 – User Menu Diagram ................................................................................................................... 10
Figure 6 – Optimum Depth of Probe in Sample .......................................................................................... 19
Figure 7 – Manual Titration ......................................................................................................................... 20
Figure 8 – Automatic Titration ..................................................................................................................... 21
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1. Product Description
1.1 General
The Laboratory Charge Analyzer (LCA) is used to
determine the charge demand (aka coagulant
demand) of an aqueous sample like raw water
coming into a water treatment plant. The LCA
performs a titration of the sample using
coagulants (or polymers) until the sample’s
charge is neutralized. The LCA provides a realtime measurement of charge neutralization using
streaming current technology. Streaming current
is a term which is commonly interchanged with
“charge” or “charge measurement.” Streaming
current is a very small current that is generated
by the mechanical separation, or shearing, of ions
from the diffuse layer that surrounds charged
species like macromolecules and colloidal
particles (Figure 1).
A streaming current device (Figure 2) is easily
identified by its reciprocating plastic piston that
travels inside the annulus of a plastic probe fitted
with two electrodes. The movement of the piston
displaces the liquid in the annulus, forcing the
liquid to travel rapidly across the piston surfaces.
Soluble and colloidal charged species in the
sample momentarily attached to the reciprocating
piston via Van Der Waals attraction forces, and
the rapid fluid motion across the piston surface,
causes loosely bound counter-ions to be sheared
away from the charged species attached to the
cylinder walls. Electrodes in the cylinder
measure this tiny current generated by the
sheared counter-ions. The signal is electronically
processed and the resulting readout is called the
streaming current value (SCV), which can be
thought of as a mV value, but actual correlation
to a true mV value is not possible unless the
instrument is specially calibrated using zeta
potential measurement.
The SCV is sometimes referred to as “Particle
Charge” or “Ionic Charge” measurement by other
manufacturers.
The LCA-3 is unique among lab charge analyzers
in that it can control the pH during the charge
titration and this allows the LCA to more
accurately determine the optimum coagulant
dosage (versus those units which cannot control
pH). Sample pH is especially important when
working with inorganic coagulants and pH must
be taken into consideration when performing
titrations in order to obtain accurate charge
demand analysis results.
Higher alkalinity samples may require the pH to
first be lowered with additions of Acetic in order
to ensure the aluminum species are in the correct
form for charge analysis (this is akin to chlorine
measurements where the sample pH is buffered
to improve measurement accuracy). Lower
alkalinity samples will possibly require the
addition of a base (e.g.. sodium hydroxide). This
manual attempts to cover the most important
aspects of the laboratory charge analysis testing
procedures, but it is very important to realize that
several factors will impact the measurement
result. It is highly recommend to consult with
Chemtrac’s application experts to ensure the test
procedure is optimized for plant conditions.
Figure 1 - Double Layer Charge
Figure 2 - Streaming Current Sensor
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1.2 Applications
1.2.1 Determining Coagulant Dosage
In water treatment applications, the LCA provides
a fast and simple method of determining the
optimum coagulant or polymer dosage needed
for maximum removal of turbidity (NTU) and
organics (NOM/TOC).
1.2.2 Determining Caustic Dosage
The LCA-3 with its automatic pH titration can be
used to determine how much base (e.g. caustic,
lime) is needed along with coagulant to achieve
optimum pH conditions for coagulation.
1.2.3 Determining Polymer Dosage
In wastewater applications, the LCA can
potentially be used to help optimize polymer
dosage for clarification and dewatering.
Measurements of centrifuge centrate, or gravity
belt thickener or belt filter press filtrate, can be
made to see where charge is running, and
confirm proper dosing.
1.2.4 Charge Demand
In Pulp & Paper applications, the LCA is used to
determine the cationic or anionic charge demand
of a sample which helps quantify swings in
charge that can occur on the paper machine.
Charge demand is determined by titrating a
sample with a polymer of opposite charge
(typically DADMAC or PVSK).
1.2.5 Determination of Isoelectric Point
The LCA can be used to find the Isoelectric Point
(IEP) of dispersions using an Acid or Base
titration. The IEP is the pH at which a particular
molecule or particle carries no net electrical
charge.
If the sample is cationic, the sample is titrated
with a base until the SCV value reaches 0 (or
neutral). If the sample is anionic, an acid is used
instead.
1.2.6 Other Applications
The LCA can be used in a variety of other
applications where soluble/colloidal charge is of
concern.
1.3 Model Designation
The LCA comes in three models which are
identified as LCA-1, LCA-2, and LCA-3. The
model number is located on the instruments
identification label, which is found on the back of
the device.
LCA-1 has no internal titration pumps, requiring
all titrations to be performed manually.
LCA-2 has one internal pump for titrating the
sample with a coagulant or polymer.
LCA-3 has two internal titration pumps. One
pump is for titrating the sample with a coagulant
or polymer. The second pump can be used for
titrating the sample with an acid or base; or used
with an anionic polymer when doing charge
demand titrations. The LCA-3 comes standard
with the pH and temperature probe option.
1.4 Included Items
LCA Model:
1 2 3
Probe
Piston
Magnetic Stirrer
Stir Bar
Sample Beaker
Opt
Opt
Opt
Power Cord
pH Probe
Opt
Opt
Coag / Poly Dosing Pump
Acid / Base Dosing Pump
5 cc Graduated Cylinder
1.5 Options
1.5.1 pH and Temperature
Models LCA-1 and LCA-2 can be equipped with
the pH and temperature probe option. This option
comes standard on model LCA-3. The pH probe
allows the user to easily perform pH adjustment
prior to or during the coagulant titration. This
option also allows the user to easily conduct
testing for determining the isoelectric point.
1.5.2 Roll Away Case
The roll away case allows for easier transport and
safe storage of the LCA.
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1.6 Specifications
Dimensions Width: 8.5”
Depth: 9.2”
Height (Stand Lowered): 26”
Height (Stand Raised):
Weight 18 lbs. (8.2 kg)
Power Requirements 115VAC, 50/60Hz, 410 mA
Optional 220VAC, 50/60Hz, 205 mA
Environmental Temperature 41-140F / 5-60C
Enclosure Powder Coated Aluminum
Display Backlit LCD
Measurements LCA-1
-SCV (Streaming Current Value, or mV)
-Manual/Hand Titration
LCA-2:
-SCV (Streaming Current Value, or mV)
-Automatic Charge Titration
-Coagulant Dose (ppm, mg/l)
-Charge Demand (μeq/l)
LCA-3:
-SCV (Streaming Current Value, or mV)
-Automatic Charge Titration
-Coagulant Dose: parts per million (ppm)
-Charge Demand: μeq/l
-Automatic pH Titration
-pH & Temp (F/C)*
-Acid/Base Dose: parts per million (ppm)*
-pH of isoelectric point (optional, requires pH)*
*Also available as option on LCA-1 and LCA-2
Sample Size 225 mL to 2000 mL (250 mL, 1000 ml, or 2000 ml beaker
sizes can be used, Beakers not included)
Materials in contact with sample Delrin, 316 stainless steel, PTFE (magnetic stir bar)
Titrant Pumps (LCA-2 and -3 only) Solenoid operated micro-pump with 50 µl dispense
volume. Material of construction: POM, PTFE, FKM.
LCA-2 has single pump, LCA-3 has two pumps.
Titrant Bottles (LCA-2 and -3 only) 250 mL Nalgene Bottles
pH Probe (Optional, Standard on LCA-3) Measurement range 0 – 14.
Temp Probe (Optional, Standard on LCA-3) Measurement range 0 – 140 F
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1.7 LCA Components
Figure 3 – LCA Components
1. LCD display
2. Keypad (Menu, navigation buttons,
Motor Power, Titrate, & Prime)
3. Stand Release (raises & lowers stand)
4. Probe & piston
5. Beaker (optional, sizes may vary)
6. Magnetic stirrer with stir bar
7. Titrant container (coagulant, cationic
Polymer) LCA-2 & LCA-3 Only
8. Titrant container (acid, base, anionic
polymer) LCA-3 Only
9. Coagulant/polymer pump (LCA-2, -3)
10. Acid or base pump (LCA-3)
11. pH probe (optional, standard on LCA-3)
Temp probe (opt., standard on LCA-3)
1.7.1 LCD Display & Menu Keypad
Figure 4 – Display & Menu Keypad
1. Streaming current value (charge). Range
-1000 to +1000
2. pH reading. Range 0 to 14
3. Elapsed time. Shows how long the
titration has been running
4. Signal Health. Reads >90% when probe
signal is healthy. <90% could mean
sensor needs maintenance, or possibly
too much solids in the sample.
5. Primary dosing pump dosage. Shown
here as coagulant dosage. Will display
as ml, ppm, or µeq/l.
6. Secondary dosing pump dosage. Shown
here as base dosage. Will display as ml,
ppm, or µeq/l.
7. Menu button. Allows user to calibrate
readings and change titrator settings
8. Enter button, and Motor On / Off button.
Serves as “enter” button when in menu,
and stops and starts the motor when in
normal operation.
9. Menu navigation buttons
10. Titrate button. Starts the titration.
11. Prime button. Causes pump to dispense
50 strokes to prime and verify pump
calibration.
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1.7.2 Stand Release (Raise & Lowers Stand)
The Stand Release button on the left hand side
of the enclosure is used to raise and lower the
LCA so that a sample beaker can be placed
under the sensor.
1.7.3 Probe and Piston
The probe and piston are both made of durable
Delrin plastic. These are critical components of
the LCA which produce the streaming current
reading. Proper care and inspection of these
parts is important to maintaining accurate charge
measurement results. Refer to maintenance
instructions in this manual for proper cleaning and
care of these parts.
1.7.4 Beaker (Optional)
Beakers are not supplied with the LCA but can be
ordered with the unit if desired. Various size
beakers can be used with the LCA. The smallest
beaker is a 250 mL and the largest size beaker
that is typically recommended is 2,000 mL.
Round or square beakers, glass or plastic, are
fine to use.
1.7.5 Magnetic Stirrer and Stir Bar
The LCA is supplied with a magnetic stirrer and
stir bar. The adjustable height of the LCA allows
for other magnetic stirrer make & models to be
utilized if desired.
1.7.6 Coagulant / Polymer Titrant Container
Models LCA-2 and LCA-3 come equipped with a
250 mL Nalgene Titrant Container for coagulant
(e.g. Alum, Ferric) or polymer (e.g. Dadmac).
This titrant container is located on the left side.
The coagulant or polymer needs to be diluted
down into a 1% (or less) solution.
1.7.7 Acid / Base Titrant Container
The LCA-3 has an additional titrant container on
the right side that is to be filled with the
appropriate acid or base solution. The acid or
base titrant must be diluted (typically 1% or less)
and compatible (in the diluted form) with the
following materials: POM, PTFE, FKM. Acetic
acid is usually recommended when pH reduction
is required prior to charge titration (typically
required for higher alkalinity samples when using
coagulants like alum, ferric, or low basicity PACl).
A base like sodium hydroxide is recommended
when pH needs to be raised during the titration to
maintain optimum pH. The raising of the pH
during the charge titration may be required on
lower alkalinity / lower pH waters, especially
when feeding acidic coagulants (e.g. alum or
ferric).
1.7.8 Coagulant / Polymer Titrant Pump
The coagulant titrant pump (also referred to as
the charge titration pump) is located to the left of
the probe on models LCA-2 and LCA-3. Each
stroke of the pump delivers approximately 50 µl
of coagulant. This pump cannot be used to titrate
neat (undiluted) coagulants.
1.7.9 Acid / Base Titrant Pump
The acid/base pump (also referred to as the
buffer pump) is located to the right of the probe
on model LCA-3. Each stroke of the pump
delivers approximately 50 µl of buffer solution.
This pump cannot be used to titrate neat
(undiluted) buffers.
1.7.10 pH electrode and Temp probe
The pH electrode and temperature probe is
optional on models LCA-1 and LCA-2, but comes
standard on LCA-3 They are located to the right
side of the LCA’s probe. The pH probe is
connected to a BNC male connector for easy
removal. The temperature probe is permanently
affixed to the LCA and cannot be removed
(except by factory). The pH reading is very
important to obtaining accurate charge readings
and coagulant dosage determination on the LCA.
The probe should be kept wet at all times and put
into pH 7 buffer solution for short term storage.
Place probe in KCl storage solution for longer
term storage. Handle carefully to avoid dropping
and damaging the probe.
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