Xylem ConOx User Manual

ConOx

Operating manual

Combined Conductivity and Dissolved Oxygen Sensor

ba75383e03 10/2004

ConOx

Accuracy when

going to press

The use of advanced technology and the high quality standard of our instruments are the result of continuous development. This may result in differences between this operating manual and your instrument. Also, we cannot guarantee that there are absolutely no errors in this manual. Therefore, we are sure you will understand that we cannot accept any legal claims resulting from the data, figures or descriptions.

Reprinting - even as excerpts - is only allowed with the explicit written authorization of WTW GmbH, Weilheim. Printed in Germany.

ConOx Contents

ConOx - List of contents

1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

1.1 Structure and function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

1.2 Instrument identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

3 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

3.1 Scopes of delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

3.2 Getting the sensor ready for measuring . . . . . . . . . . . . . . . . . .32

4 Measuring / Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

4.1 Calib ra t io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

4.2 Measu ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

4.3 Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

5 Maintenance, cleaning, replacement . . . . . . . . . . . . . . . . . . 34

5.1 General maintenance instructions . . . . . . . . . . . . . . . . . . . . . . 34

5.2 Outside cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

5.3 DO module: Changing the electrolyte solution and

membrane cap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

5.4 DO module: Cleaning the electrodes . . . . . . . . . . . . . . . . . . . .38

5.5 Checking the DO module for freedom from zero-current . . . . .40

5.6 Aging of the conductivity measuring cell . . . . . . . . . . . . . . . . . .40

5.7 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

6 What to do if... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

6.1 Error symptoms of DO measurement . . . . . . . . . . . . . . . . . . . . 42

6.2 Error symptoms of conductivity measuremen t . . . . . . . . . . . . .42

7 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

7.1 Conductivity basic module . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

7.2 Dissolved oxygen (DO) module . . . . . . . . . . . . . . . . . . . . . . . . 44

8 Wear parts and accessories . . . . . . . . . . . . . . . . . . . . . . . . . 47

Overview ConOx

1 Overview

1.1 Structure and function

The ConOx is a modular sensor for conductivity , dissolved oxygen (DO) and temperature. It consists of two basic components:

l Conductivity basic module, according to the quadripole measuring princi-

ple, with integrated temperature sensor

l Removable dissolved oxygen module, according to the galvanic measur-

ing principle

Structure of the

ConOx

Conductivity basic module

41, 2 3 5

78961110 12

Dissolved oxygen (DO) module

1 Voltage electrode (inside, 2x) 2 Current electrode (ring, 2x) 3 Temperature sensor in a graphite enclosure 4 Shaft 5 Connection head 6 WP 90 membrane cap (filled with electrolyte solution) 7 Gold working electrode (cathode) 8 Insulator 9 Lead counter electrode (anode) 10 Screw thread base with ventilation area 11 Cap nut 12 Plug connection 13 Closing cap for conductivity basic module 14 Closing cap for DO module

ConOx Overview

The conductivity basic module can be used as an independent conductivity measuring cell. For this pu rpose, unscrew the DO module and cl ose the open plug connection with a closing cap.

The DO module is connected to the conductivity basic module via a watertight, three-pole plug connection. The conduc tivity basic module measures the temperature, which is required for the determination of the DO content. For this reason the DO module only works in conjuncti on with the conductivity basic module.

Recommended

fields of

application

Conductivity basic

module

Dissolved oxygen

(DO) module

l On site measurements in rivers, lakes and wastewater l fishfarming l Ground water measurements l Applications in water laboratories

1.2 Instrument identification

A series number is printed on both ConOx modules. Keep these numbers ready if you have questions to ask the WTW service department. The series numbers contain the following information:

The number is printed on the shaft.

12 3

03360013

The number is printed on the cap nut.

1234

0342A007

1 Manufacturing year 20... (example: 2003) 2 Calendar week of manufacturing (CW 36) 3 Sequential batch number (0013)

1 Manufacturing year 20... (example: 2003) 2 Calendar week of manufacturing (CW 42) 3 Sensor type (type A) 4 Sequential batch number (007)

Safety ConOx

2Safety

This operating manual contains special instructions that must be followed during the operation of the sensor.

Always keep this operating manual in the vicinity of the sensor.

Special user

qualifications

General safety

instructions

The membrane cap of the DO module is filled with a small amount of an alkaline electrolyte solution. All maint enance work t hat requi res deali ng wit h the electrolyte soluti on must only be carr ied out by persons who know how to deal with chemicals safely.

The individual chapters of thi s operating manual use safety labels like the one below to indicate danger:

Caution

indicates instructions t hat must b e followed pr ecisely in orde r to avoid slight injuries or damage to the instrument or the environment.

3 Commissioning

3.1 Scopes of delivery

3.1.1 Scope of delivery of the ConOx

l ConOx combination conductivity and DO sensor,

DO module filled with electrolyte soluti on and ready to use

l 1 closing cap for conductivity basic module l 1 closing cap for DO module l 3 exchange membrane caps, WP 90 l Calibration and storage vessel, OxiCal l Polishing strip, SF 300 l Electrolyte solution, ELY/G l Cleaning solution, RL/G l Operating manual for ConOx

Note

The membrane cap that is mounted on the DO sensor for delivery serves mainly as a transport protection. Depending on the duration of the transport and storage period, it may have a shortened oper ational lifetime. If the measuring system cannot be calibrated (error message on the ins trument), please proceed according to section secti on 5.3 DO

ELECTROLYTE SOLUTION AND MEMBRANE CAP.

-CX

MODULE: CHANGING THE

ConOx Commissioning

3.1.2 Scope of delivery of the conductivity basic module

l Conductivity basic module l 1 closing cap, mounted on the conductivity basic module l Operating manual for ConOx

3.1.3 Scope of delivery of the DO module

l DO module, filled with electrolyte solutio n and operabl e l 1 closing cap, mounted on the DO module l 1 exchange membrane cap, WP 90 l Polishing strip, SF 300 l Electrolyte solution, ELY/G l Cleaning solution, RL/G l Operating manual for ConOx

Note

The membrane cap that is mounted on the DO sensor for delivery serves mainly as a transport protection. Depending on the duration of the transport and storage period, it may have a shortened operati onal lifetime. If the measuring system cannot be calibrated (error message on the instr ume nt), please proceed according t o s ection sec tion 5.3 DO

ELECTROLYTE SOLUTION AND MEMBRANE CAP.

MODULE: CHANGING THE

Commissioning ConOx

3.2 Getting the sensor ready for measuring

3.2.1 M easurements with the conductivity basic module

Make sure that the plug connection is tight ly closed by the closing cap. When mounted, the closing cap (1) must be screwed on up to the stop.

Before screwing on the closing cap, check the following points:

l The sealing (2) must be clean and evenly positioned in the groove. l The plug connection and the inside of the closing cap must be clean.

Screwing on the

DO module

3.2.2 M easurements with the combination sensor

Make sure that the DO module and conductivity basic module are screwed together tightly. When mounted, the cap nut of the DO module has to be screwed on up to the stop.

21 3

Before screwing on the DO module, check the following points:

l The sealing (3) must be clean and evenly positioned in the groove. l The plug connection must be dry on both sides.

Position the DO module (1) on the conductivity basic module and carefully and with slight pressure turn it until th e guidi ng nib on the DO module locks in place in the corresponding groove on the conductivity basic module. Subsequently tighten the cap nut (2) up to the stop. The thread onl y snatches if the DO module was correctly positioned.

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