Chemtrac CCA3100 Operation Manual

OPERATIONS MANUAL

OPERATIONS MANUAL

OPERATIONS MANUALOPERATIONS MANUAL

CCA3100

CCA3100

CCA3100CCA3100

Coagulant Charge Analyzer

Revised 04/11/12 MQ

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TABLE OF CONTENTS

SYMBOL KEY & SAFETY PRECAUTIONS PAGE 4

WARRANTY INFORMATION PAGE 5

1.0 COAGULANT CHARGE ANALYZER PAGE 6

1.1 INTRODUCTION Page 6

1.2 BACKGROUND Page 6

1.3 STREAMING CURRENT AND DOUBLE LAYER Page 7

2.0 SPECIFICATIONS AND COMPONENTS PAGE 9

2.1 SPECIFICATIONS Page 9

2.2 PROBE ASSEMBLY Page 10

2.3 SIGNAL PROCESSING Page 12

3.0 OPERATION PAGE 14

3.1 SENSOR AND PISTON Page 14

3.2.1 Removal Page 14

3.2.2 Insertion Page 14

3.2.3 Standard Cleaning Procedure Page 15

3.2 REPLACEMENT PARTS Page 16

4.0 PRACTICAL CHARGE MEASUREMENT PAGE 17

4.1 CONDITIONING Page 17

4.2 CHARGE MEASUREMENT Page 17

4.3 CHARGE DEMAND (TITRATION) Page 18

4.3.1 Suggested Titration Procedure Page 19

4.3.2 Suggested Charge Measurement Procedure Page 21

4.4 APPLICATIONS Page 22

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SYMBOL KEY

Risk of Electric Shock Note

SAFETY PRECAUTIONS

BEFORE ATTEMPTING TO UNPACK, SET UP, OR OPERATE THIS
INSTRUMENT, PLEASE READ THIS ENTIRE MANUAL.

MAKE CERTAIN THE UNIT IS DISCONNECTED FROM THE POWER SOURCE
BEFORE ATTEMPTING TO SERVICE OR REMOVE ANY COMPONENT.

FAILURE TO FOLLOW THESE PRECAUTIONS COULD RESULT IN PERSONAL

INJURY OR DAMAGE TO THE EQUIPMENT.

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WARRANTY INFORMATION

Warranty: Chemtrac®, Inc. warrants its product to be free of defects in material and

workmanship for a period of one (1) year from date of shipment to the original customer. Upon

receipt of written notice from the customer, Chemtrac®, Inc. shall repair or replace (at the

discretion of Chemtrac®, Inc.) the defective equipment or components. Chemtrac®, Inc.

assumes no responsibility for equipment damage or failure caused by:

A. Improper installation, operation, or maintenance of the equipment.

B. Abnormal wear and tear on moving parts caused by some processes.

C. Acts of nature (i.e. lightning, flooding, etc.)

This warranty represents the exclusive remedy of damage or failure of the equipment. Under

no circumstances shall Chemtrac®, Inc. be liable for any special, incidental, or consequential

damage, such as loss of production, profits or product quality. The warranty cannot be

guaranteed if the customer fails to service and maintain the equipment in accordance with

Chemtrac’s written instructions and policies, as stated in the Operations Manual.

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1.0 COAGULANT CHARGE ANALYSIS

1.1 INTRODUCTION

The Coagulant Charge Analyzer (CCA) can provide valuable data concerning charge demand

and coagulation for water treatment systems. The CCA’s output is the STREAMING

CURRENT VALUE (SCV), a term which is commonly interchanged with “charge” or

“charge measurement.” A voltage and current is generated by electrically charged particles in

the sample that are momentarily attached to the cylinder walls within the probe. A

reciprocating piston causes fluid motion, which shears the loosely bound counter-ions away

from the particles attached to the cylinder walls. Electrodes in the cylinder measure this current

generated by the sheared counter-ions. The signal is electronically processed and the output is

the SCV.

The loosely bound counter-ions, mentioned above, are a component of the “double layer.” This

concept is described in Section 1.3. Both streaming current and zeta potential are based upon

the double layer principle. Therefore, the streaming current value produced by the CCA is

comparable to the well known zeta potential.

1.2 BACKGROUND

As originally developed, the streaming potential measurement utilized a capillary passage or

porous plug of the material of concern, through which the bulk fluid can be forced by an

applied pressure. Counter-ions in the diffuse layer surrounding the material then migrate with

the fluid, creating an electrical potential or current, either of which can be measured. If the

current is measured, it is termed the “streaming current.” The CCA 3100 measures the

streaming current without the need for a capillary passage or porous plug. Rather, the

laboratory unit employs a piston and probe assembly, which is completely described in the

following sections.

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1.3 STREAMING CURRENT AND THE DOUBLE LAYER

Surface chemistry and physics are important to water treatment chemistry and the

destabilization of colloidal particles that naturally occur in water. One branch of surface

chemistry is colloidal chemistry, which is the study of a stable combination of particles that are

dissolved or suspended in a second substance. Two important aspects of colloidal chemistry

are the particle sizes (on the order of microns) and the net charge of these particles. Because of

their small size, surface area plays a major role in their behavior, along with the charge density

associated with each particle.

One goal of coagulation and flocculation is to reduce suspended particles (turbidity) that if

otherwise left untreated would negatively impact drinking water quality either by aesthetical,

chemical, or microbiological contamination. Generally, naturally occurring particles carry a

net negative charge in raw water. Positively charged coagulants are effective in aggregating the

smaller particles into larger, more filterable, particles through collisions brought about by

mixing with raw water. The cationic floc particles formed during coagulation react with the

surface of the anionic colloid to destabilize its charge structure. The Diffuse layer, or the outer

layer of the colloid, holds ions that are spaced further apart and can be displaced when a shear

force is applied. The CCA effects the shearing of counter-ions, and then measures the current

generated by the movement of these cationic particles. This is how the streaming current value

is measured by the CCA

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