Idronaut OCEAN SEVEN 306 User manual

OCEAN SEVEN 306

pH and redox probe

OPERATOR'S MANUAL

OCEAN SEVEN and Idronaut are registered trademarks of Idronaut S.r.l.

Other products and services mentioned in this document are identified by the trademarks or service marks of their respective

companies or organisations. No part of this publication, or any software included with it, may be reproduced, stored in a retrieval

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the prior written permission of the copyright holder. Idronaut S.r.l. provides this document as is without warranty of any kind either

expressed or implied including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose.

Idronaut S.r.l. may make changes of improvements in the equipment, software, firmware, or specifications described in this document

at any time and without notice. These changes may be incorporated in new releases of this document. This document may contain

technical inaccuracies or typographical errors. Idronaut S.r.l. waives responsibility of any labour, materials, or costs incurred by any

person or party as a result of using this document. Idronaut S.r.l. shall not be liable for any damages (including, but not limited to,

consequential, indirect or incidental, special damages, or loss of profits or data) even if they were foreseeable and Idronaut S.r.l. has

been informed of their potential occurrence arising out of or in connection with this document or its use.

IDRONAUT –Brugherio (MI) OCEAN SEVEN 306 12-2015

This document may not, in whole or in part, be copied, photocopied, reproduced, translated, or reduced to

any electronic medium or machine-readable form without prior consent in writing from IDRONAUT S.r.l.

About this manual

This manual will serve as a guide to you when you use the OCEAN SEVEN 306 probe.

Use it to understand the purpose of each of the OCEAN SEVEN 306 probe components and

functions.

It will help you to understand the OCEAN SEVEN 306 probe behaviour.

It will serve you as a reference when some problems arise when using the OCEAN SEVEN 306

probe.

Software updates and technical support

Please visit our website download area for software updates and technical support: http://www.idronaut.it

Warranty

The OCEAN SEVEN 306 probe is covered under a one-year limited warranty that extends to all parts and

labours and covers any malfunction that is due to poor workmanship or due to errors in the manufacturing

process. The warranty does not cover shortcomings that are due to the design, nor does it cover any form of

consequential damage as a result of errors in the measurements. If there is a problem with your IDRONAUT

OCEAN SEVEN 306 probe, first try to identify the problem by following the procedure outlined in the

troubleshooting section of this manual, if any. Please contact your representative or IDRONAUT S.r.l.. if the

problem is identified as a hardware problem or if you need additional help in identifying the problem.

Please make sure to contact IDRONAUT S.r.l. to obtain the relevant instructions before the OCEAN

SEVEN 306 probe is returned to IDRONAUT (see cleaning instructions).

For systems under warranty, IDRONAUT S.r.l. will attempt to ship replacement parts before the

malfunctioning part is returned. We encourage you to contact us immediately if a problem is detected and

we will do our best to minimize the downtime. Every effort has been made to ensure the accuracy of this

manual. However, IDRONAUT S.r.l. makes no warranties with respect to this documentation and disclaims

any implied warranties of merchantability and fitness for a particular purpose. IDRONAUT S.r.l. shall not be

liable for any errors or for incidental or consequential damages in connection with the supply, performance

or use of this manual or the examples herein. The information in this document is subject to change without

notice.

Disposal of Waste Equipment by Users in the European Union

The recycling bin symbol on the product or on its packaging indicates that this product must not be disposed

of with your other waste. It is your responsibility to dispose of your waste equipment by handling it over to

a designated collection point for the recycling of waste electrical and electronic equipment. The separate

collection and recycling of your waste equipment at the time of disposal will help to conserve natural

resources and ensure that it is recycled in a manner that protects human health and the environment. For

more information about where you can drop off your waste equipment for recycling, please contact your

local city office, your waste disposal service.

IDRONAUT –Brugherio (MI) OCEAN SEVEN 306 12-2015

TABLE OF CONTENTS

1. INTRODUCTION 1

1.1. pH AND REFERENCE SENSORS 1

1.1.1. pH sensor 1

1.1.2. Reference sensor 2

1.2. THE REDOX SENSOR 2

1.3. TECHNICAL SPECIFICATIONS 3

1.3.1. AISI 316L housing - 600 bar 3

1.3.2. White POM housing - 150 bar 4

1.4. SENSOR WIRING 7

1.5. SHIPPING LIST 8

2. DAILY OPERATIONS 8

3. CALIBRATION 8

3.1. REFERENCE SENSOR QUALITY 8

3.2. pH BUFFER TRUE VALUE 9

4. pH CALCULATION AND CORRECTION 9

5. REDOX CALCULATION 10

6. MAINTENANCE 11

6.1. REFERENCE SENSOR 11

6.2. pH SENSOR 11

6.2.1. To etch the sensor, perform the following: 11

6.2.2. Important remark on the pH measurement 12

6.3. REDOX SENSOR 12

7. OCEAN SEVEN 306 –ELECTRONIC SCHEMATICS 13

7.1. CUSTOMIZATION of the pH SENSOR MEASURING RANGE 15

7.2. DETERMINATION OF THE pH SLOPE FACTOR 15

OCEAN SEVEN 306 - pH and redox probe 1

IDRONAUT –Brugherio (MI) OCEAN SEVEN 306 12-2015

1. INTRODUCTION

The OCEAN SEVEN 306 pH and redox combined sensor probe is provided with an analogue output

0..5V and allows the in situ determination of pH and redox (oxidation reduction potential) in natural

waters as oceans, lakes, rivers and estuaries, at depths down to 600 bar. The OCEAN SEVEN 306 pH

and redox combined sensor, is specifically designed to simplify the integration in CTD probes.

1.1. pH AND REFERENCE SENSORS

The measurement of pH in seawater demands high accuracy since seawater has a high ionic strength

and is weakly buffered. The pH range in the oceans is particularly restricted and, only in very special

cases, the observed values are outside the range of 7.8 and 8.4 pH and, in some seas, the range extends

from 6.5 to 9.0 pH. Some problems have always arisen from the use of traditional reference sensors

with porous diaphragms, when measuring the pH in seawater, in particular at pressures in excess of a

few bars, due to the high and variable junction potentials that are generated. The IDRONAUT

reference sensor is in contact with the unknown solution by means of a small hole in the glass tip. This

minimizes and stabilizes the junction potential between the inner gel electrolyte and the liquid to be

measured. The reference sensor is a Silver/Silver Chloride cell in a saturated potassium chloride solid

gel and the sensor head is made of titanium.

It is also available a reference sensor specifically developed for long-term monitoring of seawater

where the internal cell is 0.7 mol NaCl. The glass body of the sensor is fitted with a plastic hydrating

cap filled with the IDRONAUT REFERENCE SENSOR STORAGE SOLUTION based on 3-mol KCl (or

NaCl) or, if not available, even with KCl saturated solution to avoid drying of the gel when not in use.

This cap must be removed before measurements. The pH sensor has a titanium head, a glass body

and a pH sensitive glass tip, which can withstand pressures up to 150 bar or even 700 bar (special

version). During all periods of inactivity, the glass tip must be fitted with a white plastic hydrating cap

filled with the pH 7 Buffer Solution, or simply with clean water. This is to prevent the pH-sensitive

glass from dehydration, which slows down the sensor response. This cap must be removed before

measurements.

1.1.1. pH sensor

Type: blue glass membrane (100 MOhm @ 20°C).

Measurement range: 0..+14 pH.

Accuracy: 0.01 pH.

Resolution: 0.001 pH.

Drift: 0.05 pH/month.

Response time: 3 s.

Max pressure: 700 bar.

Sensor body: titanium.

Compensation: automatic thermal compensation.

Life: 2 years if intensively used to for

monitoring, up to 4 years if used weekly for

daily profiling or monitoring.

Calibration frequency: monthly.

Maintenance: glass membrane renewing using the pH Sensor

Etching Solution.

OCEAN SEVEN 306 - pH and redox probe 2

IDRONAUT –Brugherio (MI) OCEAN SEVEN 306 12-2015

1.1.2. Reference sensor

Internal cell: Ag/AgCl filled with solid gel.

Max pressure: 700 bar.

Sensor body: titanium.

Life: 1 year if intensively used for monitoring,

up to 2 years if used weekly for daily

profiling or monitoring.

Maintenance: stored with the Reference Sensor Storage

Solution.

WARNING

The above stated life performance implies that the pH and reference sensors are

properly hydrated by means of the hydrating plastic cap filled with distilled

water for the pH sensor and with the Reference Sensor Storage Solution for the

reference sensor.

STANDARD POTENTIALS OF THE SILVER/SILVER CHLORIDE REFERENCE ELECTRODE

FILLED WITH SATURATED KCl WITH RESPECT TO THE HYDROGEN ELECTRODE

Temperature °C Uo (mV)

0 220,5

5 216,1

10 211,5

15 206,8

20 201,9

25 197

30 191,9

35 186,7

40 181,4

45 176,1

50 170,7

55 165,3

60 159,8

65 154,3

1.2. THE REDOX SENSOR

The REDOX sensor measures the oxidation-reduction potential of the REDOX couples present in the

medium; it makes use of the same reference sensor of pH as a reference. The sensor itself consists of a

platinum wire, which ends at the tip of the glass body (in which it is embedded), where the glass

body is rounded. The REDOX state of any natural environment is the result of a combined effect of

chemical and biological processes of reversible and/or irreversible nature and, therefore, difficult to

define. Because of the number of unknown reactions and lack of reversibility, the measured potential

is not representative of a true Eh value but is only the e.m.f. of an electrochemical cell (e.g. Pt +

reference electrode). Such cell difference potentials measured in natural environments are still very

often referred to the hydrogen scale and expressed as REDOX potentials or Eh. The potential of our

reference electrode (Ag / AgCl; KCl sat.) is +202 mV at 20° C which is to be added to the measured

value. Therefore, if for example we measure a value of 100 mV, the true Eh value is +302 mV, whereas,

if we measure a value of -100 mV, the true Eh value is +102 mV, and so on. In other words, the positive

OCEAN SEVEN 306 - pH and redox probe 3

IDRONAUT –Brugherio (MI) OCEAN SEVEN 306 12-2015

potential of the reference electrode with respect to hydrogen must be always added to the value

measured by our probe. When using reference electrodes different from the hydrogen ones, it is usual

practice to present data as Eh by obviously taking into account the potential of the reference electrode

with respect to the hydrogen electrode. For this reason, we present REDOX data as Eh.

Type: platinum electrode.

Measurement range: -1000 to +1000 mV.

Accuracy: 1 mV.

Resolution: 0.1 mV.

Max Pressure: 700 bar.

Response time 3s.

Sensor Body: titanium.

Compensation: none.

Life: unlimited.

Calibration frequency: not available.

Maintenance: cleaning of the glass/Pt surface with

special sandpaper.

1.3. TECHNICAL SPECIFICATIONS

1.3.1. AISI 316L housing - 600 bar

Measuring principle: potentiometric

pH sensor: glass membrane

Redox sensor: platinum electrode

Reference sensor: Ag/AgCl double bridge

Measuring range:

pH 3..11 pH (*)

Redox +/- 1000 mV

Accuracy: pH 0.03 pH

Redox +/- 10mV

Resolution: pH 0.01 pH

Redox +/- 2mV

Time constant: t63% < 1 s

Temperature range: -2.. +38°C

Output: pH: 0..5 VDC

Redox: 0..5 VDC (**)

Power supply: 12VDC (11..15 VDC)

Power consumption: 30 mA@12 VDC

Mechanics:

Probe housing: AISI 316L

Sensors body: titanium

Probe diameter: 48.5 mm

Probe length: 325 mm (includes bulkhead connector)

OCEAN SEVEN 306 - pH and redox probe 4

IDRONAUT –Brugherio (MI) OCEAN SEVEN 306 12-2015

Connectors:

Bulkhead male connector: IMPULSE IE55-1206-BCR

Dummy connector: IMPULSE IE55-1206-SCP

Mating female pigtail (1.8m): IMPULSE IE55-1206-CCP

Bulkhead male connector pin-outs:

Pin 1: power GND

Pin 2: analogue GND

Pin 3: pH 0..5V analogue output

Pin 4: power supply 12VDC (11..15 VDC)

Pin 5: redox 0..5V analogue output

Pin 6: not connected

Pigtail (2m) female connector and wire colours:

Pin 1: white power GND

Pin 2: black analogue GND

Pin 3: red pH 0..5V analogue output.

Pin 4: green power supply 12VDC (11..15 VDC)

Pin 5: blue redox 0..5V analogue output

Pin 6: brown not connected

(*) The pH electronic range is customizable to: 0..14 pH, 2..12 or 3..11(default), see the description

in the HW schematic section.

(**) The Redox electronic measuring range is +/- 2000 mV. An offset of +2500mV is imposed on the

Redox sensor output to obtain a positive voltage from +500 mV up to +4500 mV. Calculation on

how to obtain the true Redox value is described in a dedicated section.

1.3.2. White POM housing - 150 bar

Measuring principle: potentiometric

pH sensor: glass membrane

Redox sensor: platinum electrode

Reference sensor: Ag/AgCl double bridge

Measuring range:

pH 3..11 pH (*)

Redox +/- 1000 mV

Accuracy: pH 0.03 pH

Redox +/- 10mV

Resolution: pH 0.01 pH

Redox +/- 2mV

Time constant: t63% < 3 s

Temperature range: -2.. +38°C

Output: pH: 0..5 VDC

Redox: 0..5 VDC (**)

Power supply: 12VDC (11..15 VDC)

Power consumption: 30 mA@12 VDC

1 - Bulkhead connector face view

OCEAN SEVEN 306 - pH and redox probe 5

IDRONAUT –Brugherio (MI) OCEAN SEVEN 306 12-2015

OCEAN SEVEN 306 - pH and redox probe 6

IDRONAUT –Brugherio (MI) OCEAN SEVEN 306 12-2015

Mechanics:

Probe housing: POMwhiteplastic,150bar(1500mdepth)

Sensor heads: titanium

Probe diameter: 75 mm

Probe length: 480 mm (including hanging rod)

Probe weight: 1,7 kg in air

0,7 Kg in water

Connectors:

Bulkhead male connector: IMPULSE MCBH (WB)-6-FSTi/12”

Dummy connector: IMPULSE MCDC-6-FS

Mating female pigtail (1.8m): IMPULSE MCIL-6-FS

Bulkhead male connector pin-outs:

Pin 1: power GND

Pin 2: analogue GND

Pin 3: pH 0..5V analogue output

Pin 4: power supply 12VDC (11..15 VDC)

Pin 5: redox 0..5V analogue output

Pin 6: not connected

Pigtail (2m) female connector and wire colours:

Pin 1: black power GND

Pin 2: white analogue GND

Pin 3: red pH 0..5V analogue output.

Pin 4: green power supply 12VDC (11..15 VDC)

Pin 5: blue redox 0..5V analogue output

Pin 6: brown not connected

(*) The pH electronic range is customizable to: 0..14 pH, 2..12 or 3..11(default), see

the description in the HW schematic section.

(**) The true redox output is +/- 2000 mV. An offset of +2500mV allows the redox

sensor to operate in the positive voltage realm. Therefore the redox sensor

output is +500 mV to +4500 mV. Calculation on how to obtain Redox value are

described in a dedicated section.

Bulkhead connector face view

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