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ISO 9001

Technical InformationTI 375C/07/en/06.0351513127

pH ElectrodesOrbiPore CPS 91

pH electrodes with open aperture for heavily soiled media, with optional built-in temperature sensor

Application

• Chemical processes• Heavily soiled media:

– Solids– Emulsions– Precipitation

Your benefits

• Low maintenance due to gel filling • Open aperture for application in heavily

soiled media • Built-in temperature sensor for effective

temperature compensation (optional)• Long service life due to new stabilised

gel• Extremely insensitive to pressure and

temperature variation• Short response time• Double junction reference system

protecting from electrode poisoning

�With ATEX and FM approval for application in hazardous areas

OrbiPore CPS 91

2 Endress+Hauser

Function and system design

Measuring principle pH measurementThe pH value is used as a unit of measurement for the acidity or alkalinity of a liquid medium. The membrane glass of the electrode supplies an electrochemical potential which is dependent upon the pH value of the medium. This potential is generated by the selective penetration of H+ ions through the outer layer of the membrane. An electrochemical boundary layer with an electric potential forms at this point. An integrated Ag/AgCl reference system serves as reference electrode.The transmitter converts the measured voltage into the corresponding pH value using the Nernst equation.

Important properties • Open apertureDue to its open aperture, the CPS 91 electrode can be applied in heavily soiled media.

• Temperature compensationDepending on the ordered version, a Pt 100 or Pt 1000 temperature sensor is integrated in the electrode to measure the medium temperature.

• Easy connectionThe electrode is connected via a GSA plug-in head or via the water-proof TOP 68 plug-in system (IP 68).

• DurabilityThe electrode is pressure-proof up to 13 bar / 188.5 psi and can be applied with temperatures of up to 110 °C / 230 °F.

Measuring system A complete measuring system comprises:• CPS 91 pH electrode• Transmitter, e.g. Liquisys M CPM 223/253• Special measuring cable, e.g. CPK 9• Immersion, flow or retractable assembly, e.g. CleanFit P CPA 472

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Input

Measured variables pH valueTemperature

Measuring range 0 ... 14 pH0 ... 110 °C / 32 ... 230 °F

� Caution! Please note the process operating conditions.

Installation

Installation instructions Do not install the electrode overhead. The angle of inclination must be at least 15° from the horizontal. A smaller installation angle is not allowed since such an angle results in air cushion forming in the glass sphere. This may impair full wetting of the pH membrane with the inner electrolyte.

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Environment

Ambient temperature

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Do not operate the sensor at temperatures below –15 °C / 5 °F.

Storage temperature 0 ... 50 °C / 32 ... 122 °F

Ingress protection IP 67 with GSA plug-in headIP 68 with TOP 68 plug-in head (1 m / 3.28 ft water column, 50 °C / 122 °F, 168 h)

not permissible!not permissible!

permissible installation angle

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Process

Process temperature 0 ... 110 °C / 32 ... 230 °F

Process pressure 0 ... 13 bar / 188.5 psi

Pressure-temperature load curve

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Conductivity min. 10 µS/cm

pH range 0 ... 14 pH

� Caution! Danger of damage to the electrodeDo not operate the electrode in applications outside the given specifications!

400 20 60 80 110

0

8

4

T [°C]

p [

bar

]

32 68 104 230140

58

116

174

p [

psi

]

T [°F]

2

6

10

12

14

176

29

87

145

13 188.5

Application range CPS 91

OrbiPore CPS 91

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Mechanical construction

Design, dimensions

Weight approx. 0.1 kg / 0.2 lb.

Material

Process connection Pg 13.5

Temperature sensor Pt 100, Pt 1000

Plug-in heads

Electrolyte Reference electrolyte with a polymer concentration ≤ 9.8 %Cationic cross-linked and stabilised gel

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Ø 12 /Ø 0.47

120,

225

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72, 8

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14.

17, 1

6.73

mm / inch

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120,

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, 360

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72, 8

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Electrode shaft glass, suitable for processespH membrane glass type BMetal lead Ag/AgClDiaphragm open aperture

ESA plug-in head Pg 13.5, TOP 68 for electrodes with or without temperature sensor, 16 bar / 232 psi, Ex

GSA plug-in head Pg 13.5 for electrodes without temperature sensor

OrbiPore CPS 91

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Certificates and approvals

Ex approval CPS 91 (ESA) • ATEX II 1G EEX ia IIC T4/T6• FM Class I Div. 2, in combination with the MyPro CPM 431 and Mycom S CPM 153 transmitters

TÜV certificate TOP 68 plug-in head

Pressure resistance 16 bar, min. triple safety overpressure

Ordering information

Product structure CPS 91 Electrode type1 without temperature sensor2 with built-in Pt 100 (not available with GSA plug-in head)3 with built-in Pt 1000 (not available with GSA plug-in head)

Application rangeBO pH = 0 ... 14, T = 0 ... 110 °C / 32 ... 230 °F

Shaft length2 120 mm / 4.72"4 225 mm / 8.86"5 360 mm / 14.17"6 425 mm / 16.73"

Plug-in headESA Plug-in head Pg 13.5, TOP 68, 16 bar / 232 psi, ExGSA Plug-in head Pg 13.5, DIN coax, non ExSIX Plug-in head, Pg 13.5, Sixplug, non Ex

CPS 91- complete order code

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Accessories

Assemblies ❑ CleanFit W CPA 450Manually operated retractable assembly for pH electrodes, for the installation of 120 mm electrodes in tanks and pipes,Ordering acc. to product structure, see Technical Information (TI 183C/07/en)

❑ CleanFit P CPA 471Compact retractable stainless steel assembly, for the installation in tanks and pipes, manual or pneumatic operation;Ordering acc. to product structure, see Technical Information (TI 217C/07/en)

❑ CleanFit P CPA 472Compact retractable plastic assembly, for the installation in tanks and pipes, manual or pneumatic operation;Ordering acc. to product structure, see Technical Information (TI 223C/07/en)

❑ CleanFit P CPA 473Retractable stainless steel process assembly, with ball valve for a particularly safe and reliable separation of the medium from the environment;Ordering acc. to product structure, see Technical Information (TI 344C/07/en)

❑ CleanFit P CPA 474Retractable plastic process assembly, with ball valve for a particularly safe and reliable separation of the medium from the environment;Ordering acc. to product structure, see Technical Information (TI 345C/07/en)

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❑ DipFit W CPA 111Plastic immersion and installation assembly, for open and closed tanks;Ordering acc. to product structure, see Technical Information (TI 112C/07/en)

❑ FlowFit W CPA 250Flow assembly for pH and ORP measurementOrdering acc. to product structure, see Technical Information (TI 041C/07/en)

Buffer solutions Technical buffer solutions, accuracy 0.02 pH, acc. to NIST/DIN❑ pH 4.0 red, 100 ml (0.026 US gal.), order no. CPY 2-0❑ pH 4.0 red, 1000 ml (0.264 US gal.), order no. CPY 2-1❑ pH 7.0 green, 100 ml (0.026 US gal.), order no. CPY 2-2❑ pH 7.0 green, 1000 ml (0.264 US gal.), order no. CPY 2-3

Technical buffer solutions for single use, accuracy 0.02 pH, acc. to NIST/DIN❑ pH 4.0 20 x 20 ml (0.005 US gal.), order no. CPY 2-D❑ pH 7.0 20 x 20 ml (0.005 US gal.), order no. CPY 2-E

Measuring cables ❑ CPK 9 special measuring cableFor pH-/redox electrodes with TOP 68 plug-in headOrdering acc. to product structure, see Technical Information (TI 118C/07/en)

❑ CPK 1 special measuring cableFor pH-/redox electrodes with GSA plug-in headOrdering acc. to product structure, see Technical Information (TI 118C/07/en)

❑ CPK 12 special measuring cableFor pH-/redox glass electrodes and ISFET sensors,Ordering acc. to product structure, see Technical Information (TI 118C/07/en)

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Documentation

Transmitters ❑ Liquisys M CPM 223/253, Technical Information TI 194C/07/en; order no. 51500277❑ Mycom S CPM 153, Technical Information TI 233C/07/en; order no. 51503788❑ MyPro CPM 431, Technical Information TI 173C/07/en; order no. 50088309

Assemblies ❑ CleanFit P CPA 450, Technical Information TI 183C/07/en; order no. 50090677❑ CleanFit P CPA 471, Technical Information TI 217C/07/en; order no. 51502596❑ CleanFit P CPA 472, Technical Information TI 223C/07/en; order no. 51502645❑ CleanFit P CPA 473, Technical Information TI 344C/07/en; order no. 51510923❑ CleanFit P CPA 474, Technical Information TI 345C/07/en; order no. 51510925❑ DipFit W CPA 111, Technical Information TI 112C/07/en; order no. 50066450❑ FlowFit W CPA 250, Technical Information TI 041C/07/en; order no. 50036058

Measuring cables ❑ CPK 1-12, Technical Information TI 118C/07/en; order no. 50068526

OrbiPore CPS 91

10 Endress+Hauser

OrbiPore CPS 91

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Endress+Hauser GmbH+Co. KGInstruments InternationalP.O. Box 2222D-79574 Weil am RheinGermany

Tel. (07621) 975-02Tx 773926Fax (07621) 975 345e-mail: info@ii.endress.com

Internet:http://www.endress.com

11.01

TI 375C/07/en/06.0351513127Printed in Germany / FM+SGML 6.0 / DT