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pH measurement in industrial processes

pH measurement in industrial
processes
Selection and engineering guidefor different industries andapplications

Step by step
pH determination is an essential measurement
in all industries. Monitoring of product quality
or of chemical reactions is often done by meansof pH measurement. The pH value is related
to the hydrogen ion (H+) concentration in an
aqueous solution and therefore to the solution’s
acidity. The pH value can (in theory) vary in water
between 0 – 14, with 0 being the acidic and 14 thecaustic end of the scale.

The lifetime of a pH sensor depends on these
conditions, but as well on cleaning, calibration,
regeneration intervals and on the right choiceof sensor type. A complete pH measuring pointconsists of the sensing element (pH sensor),an assembly, cable and transmitter. This guidehelps you with the selection of the right sensor
and assembly for your applications including thetransmitter.

Application conditions for pH measurement canbe very different ranging e.g. from wastewaterand chemical mixtures to ultra pure water inpower stations or the life science industry.

For further detailed information, also crosscheck the related Technical Information of thechosen products. This guide does not claim to becomplete.

Overview of pH
measurement
equipment

Selection of pH sensor
according toapplication

This part comprises a short
description of different typesof necessary components:

Starting with a flow chart[3.1] this part supports you
to do a proper pre-selection
based on chemical andphysical behaviors of theprocess medium. From
there you are directed to theindividual chapters [3.2 –3.8] with the indication of
the recommended pH sensor
including key advantages aswell as application limits andalternatives.

• pH sensors• Assemblies• Transmitters
Each part contains technicaldescriptions followed bytables summarizing technicaldata including advantages
and application limits.

Check list/data sheet

For a complete specificationa check list is provided withthe option to add a sketch of
the installation conditions.
Please use this format for
professional inquiries.

A
2

B

Selection of assembly
for a given application
After pH sensor selection,
the assemblies part also
starts with a flow chart [4.1]
guiding to the individual
chapters [4.2 - 4.5] based on
installation and application
conditions. Similar to part
B you will be given a first
choice plus alternatives.
Depending on pH sensor“liquid- or gel-filled” youneed to specify respectively
order corresponding optionsof a retractable assembly.
Additionally, make sure toselect a pneumatically driven
retractable assembly in case
you want to use Liquiline
Control for automatic
measuring, cleaning andcalibration.
Based on the selected pH
sensor in part B pleasecheck mechanicalcompatibility [table in 4.6]
to verify corresponding pH
sensor length and max.
required free space formounting assemblies e.g.
in pipes, bypasses or small
tanks.

C

Contents
1. Overview of pH sensors and installation types. . . . . . . . . . . . . . . . . 4
1.1		Sensor types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 pH sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Assembly types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
1.4 pH assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
1.5 Transmitter types for pH measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  20
1.6 pH transmitters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22

2. Check list/data sheet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

A

3. Selection of pH sensors according to applications. . . . . . . . . . . . . . 26
3.1 Flow chart for pH sensor selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  27
		
		3.2
		
3.3
		
3.4
		
3.5
		
3.6
		3.7
		3.8

Application: Standard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
Application: High organic load. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30
Application: Low conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  32
Application: Hygienic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  34
Application: Heavy-duty – abrasive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  36
Application: High risk of build-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  38
Application: Chemically demanding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  40

B

4. Selection of assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
		4.1
		4.2
		
4.3
		
4.4
		
4.5
		
4.6
			

Flow chart for assembly selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
Immersion type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  44
Fixed installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  46
Retractable assembly (with piston sealing). . . . . . . . . . . . . . . . . . . . . . . . . .  48
Retractable assembly (with ball valve). . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
Required pH sensor length and immersion depth
for various assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52

5. Life cycle management of pH loops. . . . . . . . . . . . . . . . . . . . . . . . . . 54
		
5.1 Optimum calibration concept for the lab thanks to Memosens and
		5.2
		
5.3
		
5.4
		
5.5

Memobase Plus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  54
Fully automatic measuring, calibration, sterilization and cleaning . . . . .  55
Lifetime of pH sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  56
Accreditation for permanent buffer laboratory. . . . . . . . . . . . . . . . . . . . . . .  57
Steam/water analysis systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  58

3

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1. Overview of pH sensors and installation types
1.1 Sensor types

4

Glass sensors
The sensing element of the standard
pH-glass sensor is a salt on
the glass bulb with a thicknessof 100 nm. This layer is able toincorporate H+ ions and this results
in a change of the electrostatic
potential across the glass bulb.
This potential change is measured
relative to a reference element
which is in contact to the mediumby the junction to create a closed
electrical circuit.

Different types of glass sensors areavailable, e.g. hygienic and nonhygienic versions. These differ inthe kind of junction used (ceramic,
Teflon or none) and in the kind of
gel or liquid used for the reference
system. Resistance of the sensor
against blocking of the junction andpoisoning of the reference depends
strongly on the selection of reference and junction type.

ISFET sensors
The sensing element of an ISFET
sensor is a semiconductor chip
forming an ion selective field
effect transistor. The ISFET chipis especially sensitive to H+ ions.
Non-glass sensors are unbreakable
and the ISFET sensors can toleratehigher amounts of organic solvents
than glass type sensors. Glass and
ISFET type sensors use the samereference and junction types.

Main application areas of the
ISFET type is whenever glass is
not allowed or wished, e.g. infood processes or when there arehigh amounts (> 20 %) of organic
solvents. ISFET sensors are madefrom PEEK and have a lower
alkaline and acid error compared to
glass sensors. The new generationof the ISFET sensors even offers
a six times higher CIP stability
compared to conventional ISFET pH
sensors.

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Combined pH/ORP sensors
Combined sensors feature aplatinum element in addition
to the pH glass. This enables
simultaneous measurement of pH
value and ORP potential for a better
process overview. Alternatively,
the platinum element can be used
for measurement of the reference
impedance to anticipate decreases
in sensor quality. Combined sensors
directly deliver rH values that giveinformation about a medium being
oxidizing, neutral or reducing.

Different types of glass sensors areavailable, e.g. hygienic and nonhygienic versions. These differ inthe type of junction used (ceramic,
Teflon or none). Resistance of thesensor against blocking of thejunction depends strongly on theselection of junction type.

Enamel sensor
The main advantage of enamel
sensors is their robustness. The
sensors have extraordinarily
long calibration cycles and along lifetime. The measurement
accordingly requires lessmaintenance.

Liquid KCl filled reference withhygienic ceramic junction.
The linear range is from pH 0 to
10. The sensor has a hygienic
design, suitable for CIP and SIP.
A retractable assembly is notnecessary and there are different
process connections available.

Revolutionary Memosens
technology
pH measurement has become
easier and more reliable sinceEndress+Hauser has invented
Memosens. Inductive signal andenergy transmission without
any metallic contacts between
sensor head and cable connection
ensures trouble-free operationeven in humid environments.
The storage of calibration data inthe sensor head enables comfortablecalibration in the laboratory andquick sensor exchange on site.

Memosens 2.0 is leading Memosens
technology into the future. It offers:
Perfect basis for IIoT connectivity:
You have the relevant information
on your measuring point close
to hand using the right app.
Predictive maintenance 2.0: The
storage capacity for up to 8 times more
relevant data is an excellent basis forpredicting maintenance requirements.
Increased flexibility when configuring
the measuring point in hazardous areas.
See also section 5.1 on page 54 or
www.endress.com/memosens

5

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1. Overview of pH sensors and installation types
1.2 pH sensors

Glass sensors
Memosens CPS11E
Orbisint CPS11

6

Glass sensors
Memosens CPS71E
Ceragel CPS71

Glass sensor
Memosens CPS61E

pH range

0 to 140 to 14

1 to 12 (measuring range),
1 to 14 (application)

Process temperature

0 to 135 °C

0 to 135 °C

0 to 140 °C

Max. processpressure

up to 17 barabs

up to 14 barabs

up to 7 barabs

Min. conductivity

50 µS/cm
version with salt storage:
0,1 μS/cm

10 µS/cm

100 µS/cm

Organic content< 20 vol%< 20 vol%< 20 vol%Shaft material

glass

glass

glass

Junction

PTFE

ceramic

ceramic

Reference systemgel filled

gel filled, ion trap

gel filled, ion trap

Special options

F glass for higher HF
content, ion trap for
poisoning media,
salt storage for low
conductivitypressurized reference,
upside-down mounting

Certified life sciences
and food compliance(e.g. FDA, USP, EHEDG, ...)
pressurized reference,
upside-down mounting

Applications

water, wastewater, process

chemical processes

hygienic and sterile
applications (sterilizable,
autoclavable)• bioreactor/fermenter• biotechnology• foods

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Glass sensors
Memosens CPS91E
Orbipore CPS91

Glass sensors
Memosens CPS41E
Ceraliquid CPS41

Glass sensors
Memosens CPF81E
Orbipac CPF81

Glass sensor
Memosens CPS31E
Ceratex CPS31

0 to 140 to 140 to 14

1 to 120 to 10 (measuring
range), 1 to 14(application)

0 to 110 °C

0 to 135 °C

0 to 110 °C

0 to 80 °C

0 to 140 °C

up to 14 barabs

up to 11 barabs withcounter pressure

up to 11 barabs

up to 4 barabs

up to 7 barabs

500 µS/cm

0.1 µS/cm

50 µS/cm

100 μS/cm
50 μS/cm for „AC“version (three junctions)

50 µS/cm< 20 vol%higher level possible
depending on
application< 20 vol%< 20 vol%< 20 vol%

glass

glass

glass

glass

enamel on
stainless steel

open

ceramic

PTFE

ceramic

ceramic

stabilized gelr­eference

liquid filled

gel filled, double
chambergel filledliquid filledflat membranesalt storage

wastewater, mining

drinking water,
swimming pool water,
pH compensation
for measuring freechlorine

for soiling media

emulsions, suspensions,precipitation reactions

process, ultrapure
water, fat, dye

Enamel sensor
Ceramax CPS341D

food and life sciences

7

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1. Overview of pH sensors and installation types
1.2 pH sensors

ISFET sensors
Memosens CPS77E

8

ISFET sensors
Memosens CPS97E

ISFET sensors
Memosens CPS47E

pH range

0 to 140 to 140 to 14

Process temperatur-15 to 135 ˚C-15 to 110 ˚C-15 to 135 ˚CMax. processpressure

up to 11 barabs

up to 11 barabs

up to 11 barabs

Min. conductivity

10 µS/cm

500 µS/cm

5 µS/cm

Organic content

high level possible
depending on applicationhigh level possible
depending on applicationhigh level possible
depending on application

Shaft material

PEEK, chip sealing:
perfluorelastomer

PEEK, chip sealing:
perfluorelastomer

PEEK, chip sealing:
perfluorelastomer

Junction

ceramic

open aperture

ceramic

Reference systemgel filled

stabilized gel reference

Special options

Certified life sciences andfood compliance (e.g. FDA,
USP, EHEDG, ...)

Applications

food, life sciences,
fermenter, process,non aqueous media

liquid filled
Certified life sciences andfood compliance (e.g. FDA,
USP, EHEDG, ...)

emulsions, suspensions,precipitation reactions,non aqueous media

process, pure water, fat,dye, non aqueous media

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Combined pH/ORP sensor
Memosens CPS16E

Combined pH/ORP sensor
Memosens CPS76E

Combined pH/ORP sensor
Memosens CPS96E

pH: 0 to 14
ORP: -1500 to 1500 mV
rH: 0 to 42

pH: 0 to 14
ORP: -1500 to 1500 mV
rH: 0 to 42

pH: 0 to 14
ORP: -1500 to 1500 mV
rH: 0 to 42

0 to 135 °C

0 to 140 °C

0 to 110 °C

up to 17 barabs

up to 14 barabs

up to 14 barabs

50 µS/cm

10 µS/cm

500 µS/cm< 20 vol%< 20 vol%< 20 vol%

glass

glass

glass

PTFE

ceramic

open aperture

gel filled, ion trap

stabilized gel reference

gel filled, ion trappressurized reference system, upsidedown mounting
water, wastewater, process

chemical processemulsions, suspensions, precipitation
reactions9A

1. Overview of pH sensors and installation types
1.3 Assembly types

Immersion type holders
These types of assemblies aremainly used for installations inopen vessels and channels. Suchassemblies are usually found inwastewater treatment plants
or chemical industry. Wheninstallation from top of thecontainer or vessels is the only
possibility – immersion holders
are as well a good choice.

DipfitThe standard CPA111 made frompolypropylene (PP) is mainly usedin the wastewater market. Besidethat we offer the CPA140 madefrom PVDF or stainless steel forharsher applications (e.g. chemicalindustry). Different immersion
lengths are available and both
assemblies can hold up to three
sensors for redundant or multiple
measurement. Spray cleaning
options are available for both
assemblies.

Modular immersion type holders
These types of assemblies havereal advantages in immersion
applications like in wastewaterindustries. They are suitable forsensors with various connection
threads. Not only 12 mm glass
sensors for pH or oxygen but also
sensors for turbidity or nitrate.
The System can be mounted innearly all locations (pipes, rails, etc.)
by using different pipes, holders andmore.

The modular system allows an
optimum configuration for every
measuring application

Flexdip
Flexdip CYA112 is used for
installations in open vessels
and channels. Such assemblies
are usually found in wastewater
treatment plants.
Insertion assemblies
Especially in batch processes
where you have access to the pH
sensor between two batches wefind fixed installations realized byusing insertion assemblies. Suchassemblies are often used in life
sciences and food production.

10• Using 12 mm Memosens sensors• Versions in stainless steel or PVC• Assembly length from 600 mm(23.6”) to 3600 mm (142”) in stepsof 600 mm (23.6”)• A float assembly is available forvarying water levels.
• Quick fastener for:– fast installation and exchange of		 Memosens sensors with		 non-contact plug-in head– twist-free installation of
		 fixed-cable sensors– alignment of sensors

Unifit
The CPA842 is an assembly madefrom stainless steel for food and life
sciences. There are several options
for the process connection especiallyhygienic clamp connections. For
special hygienic demands a certified
hygienic design and certificatesaccording to EHEDG, 3-A, ASME BPE
and Pharma CoC are available withcorresponding surface roughness.

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2
1

Flow-through assemblies
Installation in process pipes orbypasses can be done by using
flow-through type assemblies. Such
set-ups are often found in water
works, beverages industry, chemicalindustry or on analytical panels in
power plants.

FlowfitFor the water works segment the
CPA250 made from polypropylene(PP) is a good choice. The robust
CPA240, available in chemically resistant PVDF or made from stainlesssteel is made for measurement of
ultra pure water (prevention of static
charges). Both assemblies provide
3 sensor slots and the possibility to
upgrade for chemical spray cleaning.
For compact installations and utilities, the CYA21 could be a valuable
option.

Retractable assemblies
Main advantage of retractables isthat sensor exchange or cleaning
can easily be done without processinterruption. Insertion or retraction
can either be done manuallyor automatically (pneumatic
retraction). The pneumaticallydriven assemblies can be combinedwith automatic cleaning andcalibration system, because
the sensor resides in a cleaning
chamber after retraction.

Cleanfit
Besides the differentiation between
manual and automatic retraction,
we offer different materials, sealing
strategies to the process and safetyfunctions to fit your application. For
heavy duty applications, variants
with a ball valve based sealing
system are available. Additionallythe pneumatic version can be
combined with the fully automatedmeasuring, cleaning and calibration
solution Liquiline Control.

Liquiline Control

See also section 5.2 on page 55 orwww.endress.com/CDC90

Fully automated measuring,cleaning and calibrating
1 Media distribution unit
2 Transmitter withindustry PC andtouch display

43

3 Cleaner and buffer canisters
4 Double-membrane pumps

11

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1. Overview of pH sensors and installation types
1.4 pH assemblies(Type of sensor see table on page 52)

Flowfit CPA240

Flowfit CPA250

Flowfit CYA21

Max. processpressure

Stainless steel: 11 barabs
at 150 °C; PVDF: 9 barabs
at 50 °C

7 barabs at 20 °C

17 barabs

Process temperature

Stainless steel: -15 to 150 °C
PVDF: 0 bis 120 °C

0 to 80 °C

0 to 100 °C

Materials (in contact
with medium)

PVDF, stainless steel
1.4404/316L

Polypropylene (PP)

Stainless steel
1.4404/316L

Sealings (in contact
with medium)

EPDM/Viton/Chemraz/
Fluoraz

Viton/FKM

specific to sensor

Sensor connections

3 x PG 13.5

3 x PG 13.5

1 x PG 13.5; thread NPT½“

Process connections

welding adapter for DN 25
pipe; flange DN 25 PN 16;
flange ANSI 1” 150 lbs;
flange JIS 10K 25 A; thread
FNPT ½”

thread G 1”, thread NPT 1”

pipe, 6mm outer diameter(OD) for common tube
fitting systems

Cleaning

spray cleaning CPR31

spray cleaning CPR31,
Chemoclean CPR3-

Remarks

PMC (potential matching)in Alloy C4; Tantal

PWIS-free version
availablecompact design; ideal for
limited space applications

Applications

water, boiler feedwater,
ultra pure water, coolingwater, fertilizer, sugar
production, gas scrubbers,
petrochemical

water, wastewater
treatment or beverages

water, boiler feedwater,­ultra pure water, cooling
water

12

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Unifit CPA842

17 barabs-15 to 140 °C
Stainless steel 1.4435/316L
EPDM-FDA, FKM, FKMFDA, silicone-FDA
1 x PG 13.5
DN 25 standard; DN 25 also
for B.Braun port; Tri-Clamp
1.5’’; Tri-Clamp 2’’; dairy
fitting DN 50 DIN11851’;
Varivent DN 40-125/0.4’’,
aseptic fitting DN50 thread
DIN 11864-1A
EHEDG approval with surface
finish Ra = < 0.76 µm or <0.38 µm, 3-A
food, life sciences, chemical,
water

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1. Overview of pH sensors and installation types
1.4 pH assemblies(Type of sensor see table on page 52)

Ecofit CPA640

Dipfit CPA111

Max. process pressure

11 barabs at 90 °C, metal
11 barabs at 20 °C, PVDF

5 barabs at 20 °C

Process temperature

0 to 140 °C-10 to 80 °C

Material
PVDF, stainless steel 1.4571/316Ti,(in contact with medium) Monel

Polypropylene (PP)

Viton
Sealings(in contact with medium)

EPDM

Sensor connections

1 x PG 13,5

3 x PG 13,5

Process connections

M-NPT ½”; M-NPT ¾”; thread M 25
x 1.5

flange DN 100; adjustable flange DN
100; suspension bracket

Cleaning-

external spray cleaning CPR30,
internal spray cleaning CPR31

Remarks

application of glass
sensors with ¾“
process connections

wet bucket

Applications

water, wastewater, flocculant dosage,
surface water, industrial water monitoring, wastewater neutralisationwater/wastewater

14

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Dipfit CPA140

Flexdip CYA112

11 barabs at 150 °C, metal
7 barabs at 20 °C, PVDF

1 barabs

PVDF: 0 to 120 °C
Stainless steel: -15 bis 150 °C,­with
EPDM seal: -15 to 140 °C

0 to 60 °C

PVDF, stainless steel 1.4404/316L

PVC, stainless steel 1.4404/316L

EPDM/Viton/Chemraz/
Fluoraz

EPDM

3 x PG 13,5

1 x PG 13,5 or 1x NPT3/4“ (female)flange DN 80 PN16; flange ANSI 3” 150
lbs; flange JIS 10K 80A

thread G ¾”, 1”; thread NPT ¾”; 1 x
PG13,5external spray cleaning CPR30,
internal spray cleaning CPR31-

mounting of KCl reservoir onto theassembly

modular system,
many accessories

chemical industry, pesticides andfertilizers, petrochemical, power
plants, metal industry

water/wastewater
treatment, plant design,
open channels, basins,
open tanks and process vats,fluctuating water levels

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1. Overview of pH sensors and installation types
1.4 pH assemblies(Type of sensor see table on page 52)

Cleanfit CPA871

Cleanfit CPA875

Max. process pressure

17 barabs (depending on version)

17 barabs at 140 °C

Process temperature-10 bis 140 °C (depending on version)-10 to 140 °C

Stainless steel 1.4404/316L, Alloy C22
Material(in contact with medium) PEEK, PVDF, PVDF conductive

Stainless steel 1.4435/316L, Alloy C22

EPDM/FKM/FFKM
Sealings(in contact with medium)

EPDM-FDA/FKM-FDA/FFKM-FDA

Operation

manual/pneumatic

manual/pneumatic

Sensor connections

1 x PG 13,5

1 x PG 13,5

Process connections

clamp 2“, 2½“; flange DN 40, DN 50,
DN 80; flange 2“, 3“ (ASME B16.5);
flange JIS 10K50, 10K80; thread NPT
1½“; thread G 1¼“; dairy fitting DN 50,
DN 65

clamp 1½“, 2“, 2½“; aseptic DN 25,
DN 50; Neumo Biocontrol D 65; Neumo
Bioconnect D 50, D 65; dairy fitting
DN 50, DN 65; thread G 1¼“; Varivent
flangeConvertible topneumatic

yes

yes

Sealing to process

O-rings (2x)gasket, (version with thread G1 1/4“:O-ring)Special options

immersion chamber version,
3.1 certificate

double chamber version

Applications

water, wastewater, process

food and life sciences
processes

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Cleanfit CPA450

Cleanfit CPA451

5 barabs at 130 °C,
13 barabs (static, no movementof the assembly allowed)

3 barabs at 80 °C,
11 barabs (static, no movementof the assembly allowed)-15 to 130 °C

0 to 80 °C

Stainless steel 1.4404/316L,
Hastelloy C22 , Titanium

Stainless steel 1.4404/316L

EPDM/FKM/FFKM

FKM

manualmanual

1 x PG 13,5

1 x NPT 3/4“ (female)

G1½“ internal; G1¼“ external; NPT 1¼“
external; flange DN32 ISO 1092-1;
flange ANSI 1¼“; G1¼“ internal; NPT 1¼“
external; M-NPT 1½“ external; flange
ANSI 2“G2“ , flange DN50 Iso 1092-1,
Flange 2“ ANSInonoball valve

ball valve

Safety kit for higher process pressure,
3.1 certificate

Welding socket

water, wastewater, processwater, wastewater17

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1. Overview of pH sensors and installation types
1.4 pH assemblies(Type of sensor see table on page 52)

Cleanfit CPA472D

Cleanfit CPA473

Max. process pressure

11 barabs at 100 °C, max. 140 °C

7 barabs at 100 °C

Process temperature

0 to 140 °C

PA pressure cylinder: max. 80 °C
Stainless steel pressure cylinder: 100°C/6 bar (with continuous operation)

Material
PEEK, PVDF, conductive PVDF,(in contact with medium) Alloy C22, titanium, stainless steel
1.4571/316Ti

Stainless steel 1.4404/316L

Sealings
EPDM/FKM/FFKM(in contact with medium)

EPDM/FKM/FFKM

Operation

manual/pneumatic

manual/pneumatic

Sensor connections

1 x PG 13,5

1 x PG 13,5

Process connections

1¼ internal thread
flange DN 50,
DN 80,
2” ANSI 150 lbs
flange JIS 10K 25 A

1¼ internal thread
Tri-Clamp 2”
dairy fitting DN 65 (DIN 11 851)
flange DN 50,
2” ANSI 150 lbs

Convertible topneumatic

yes

yes

Sealing to process

O-rings (3x)ball valve

Special options

various flow assemblies
PFA-lined, 3.1 certificate

flow chamber, optionally with scrapers

Applications

heavy-duty and process applications

chemical industry, paper industry,
sticky media

18

A

Cleanfit CPA474

7 barabs at 80 °C
PP: 0 to 60 °C
PVDF/PEEK: 0 to 120 °C
Polypropylene (PP)/PEEK/PVDF

EPDM/FKM/FFKM
manual/pneumatic
1 x PG 13,5
DN 50 (DIN 11 851)
flange DN 50,
2” ANSI 150lbs

yesball valve
flow chamber, optionally with scrapers
paper industry, industrial water
treatment

19

A

1. Overview of pH sensors and installation types
1.5 Transmitter types for pH measurement

Liquiline CM44 and CM44R
The digital four-wire transmitter
offers up to 8 channels. It provides asimple and self-intuitive operation
with clear text menu in 17 languages.
Thanks to its suitability for measuring
12 different parameters you can mix
and match all Memosens sensors
in any combination. The Memosens
technology is the fundament forpredictive maintenance functionalities
because it supplies already a lotof digital sensor data and process
information.
The Heartbeat Technology available
for Liquiline CM44 ensurespermanent process and device
diagnostics, using functionalities suchas the process check system, delta

Liquiline CM42
Easy and self-intuitive operation withclear text menu in 14 languages is oneof your benefits with this two-wiretransmitter. In addition it is applicablefor Ex and Non-Ex applications.
Predictive maintenance function canbe used together with our Memosens
sensors to indicate e.g. calibration
cycles. Parameter change from pH toconductivity or dissolved oxygen iseasily done by only exchanging the20

slope, delta zero point or a calibration
timer. This helps you to optimize yourmaintenance strategy. Heartbeat
Technology also comprises verification
routines and makes it possible toautomatically generate verification
reports.
Liquiline CM44 provides up to 8
current outputs 0/4 to 20 mA, up
to 4 relays as well as fieldbuses like
HART, PROFIBUS DP, Modbus TCP/
RTU, EtherNet/IP and Profinet.
Besides the four-wire transmitter
enables a comfortable remote access
via Ethernet webserver. Liquiline
multiparameter transmitter isavailable as field device and as DINrail version for mounting in cabinets
and on DIN-rails.

sensor. Use Liquiline transmitteror Memobase Plus for calibration of
Memosens sensors in the laboratory.
Your benefit: Pre-calibrated sensors
could be exchanged in the process
very quickly and this means
considerably­fewer interruptions of pH
measurement.
Available outputs besides 4 to 20 mA
and HART are FOUNDATION Fieldbus
and PROFIBUS PA.

A
Liquiline CM14
Liquiline CM14 is a basic transmitterthat offers all you need to run astandard measuring point. It fits into
the common cabinet cut-outs and iseasy to commission thanks to digital
Memosens technology. The Memosens
hot plug & play concept allows toquickly install and commission yourdigital sensors.

Liquiline Compact CM72/CM82
The Liquiline Compact CM72 andCM82 are the smallest transmitters
for Memosens sensors and are
attached directly to the sensor
without their own power supply.
As loop-powered two-wire devices,
Liquiline compact transmitters
can also be directly connected to a
programmable logic controller (PLC),
which also serves as the power supply.
The compact transmitters measure
only 11 cm long and 2 cm wide and,
together with the sensor, can fit into
most assemblies. Despite its slenderhousing, the Liquiline Compact CM82
offers the complete flexibility andconfigurability of a multi-parametertransmitter. In addition, it is easy andreliable to operate and configure via
an encrypted Bluetooth connection
using a tablet or smartphone. Using
the SmartBlue app, you can see allmeasuring points that are within
the Bluetooth range of the device,
and configure them and generatediagnostics. The Liquiline Compact
CM72 and CM82 can be used inhazardous and non-hazardous
areas. This means that measuring
points in dangerous or difficult toaccess locations can be checked andconfigured from a safe distance.

Liquisys CPM223/CPM253
The Liquisys transmitter is available
as a panel mounted version CPM223
or with field housing CPM253. Relay
functions are available as an option(e.g. neutralization processes andspray cleaning function). 0/4 to
20 mA, HART or PROFIBUS PA/DP

outputs can be used to connect thedevice to your PLC.
The transmitter is available forpH, conductivity, dissolved oxygenand chlorine. Advanced diagnostic
functions such as detection of glass
breakage are optional.

21

A

1. Overview of pH sensors and installation types
1.6 pH transmitters

Liquiline CM44/CM44R

Liquiline CM42

Measuredparameters

pH glass, pH ISFET, ORP, conductivity,
chlorine, oxygen, turbidity, nitrate, SAC,
ammonium, sludge level, potassium,chloridepH glass, pH ISFET, ORP, conductivity,
oxygen

Input

Memosens, 4 to 20mA, digital

Memosens, analog

Channels

up to 8

single-channel

Power supply

24V DC/AC (+20/-15%)
100 to 230V AC, 50/60Hz (±15%)12.5 to 30 V DC (HART, without HART)
9 bis 32 V DC (fieldbus)

Outputup to 8 analog 0/4 to 20 mA, max. 4
digital, 8 relays, alarm relays, fieldbus
communication

up to 2 analog 0/4 to 20 mA, fieldbus
communication

Displaygraphic display with plain text guidancegraphic display with plain text guidance

Degree of protection

field device: IP66/67, NEMA Type 4X; DINrail/cabinet controller: IP20; display: IP66

IP66/67, NEMA Type 4X

Communication

HART, PROFIBUS DP, ­Modbus TCP/RTU,
EtherNet/IP, Profinet, Webserver

HART, PROFIBUS PA, FOUNDATION
Fieldbus

Housingplastic

plastic, stainless steel

Mounting

post, rail, DIN-rail, wall

wall, post, panel

Approvals

certificate of quality

certificate of quality, ex approvalSpecials• 4-wire multiparameter transmitter• Heartbeat Technology• mathematics functions• cleaning function, controller• quick setup function• modular ­expandable, SD-Card• 2-wire transmitter• quick setup function• navigator• sensor module replaceable• predictive maintenance system• also suitable for analog sensors

22

A

Liquiline CM14

Liquiline Compact CM72/CM82

Liquisys CPM253/ CPM223

pH glass, ORP, conductivity, oxygen

pH glass, pH ISFET, ORP, conductivity,
oxygenpH glass, pH ISFET, ORP

Memosens

Memosens plug-in head

Memosens, analog,

single-channel

single-channel

single-channel

24 V to 230 V AC/DC wide range power
supply12.6 to 30 V DC

100/115/230 V AC
24 V AC/DC

up to 2 analog 0/4 to 20 mA, 2 limit
contactor relays

1 analog 4 to 20 mA

2 analog (linear, optionally with user
defined characteristic curve), alarm
relays, up to 4 additional relays

2 line, LCD with dot matrix, 7 segment

LED red and green

2 line, LCD

front: IP65, NEMA Type 4X;
housing: IP20

IP 67/68, NEMA Type 6

field device: IP65, NEMA Type 4X;
panel device: IP54 (front), IP30 (housing)

CM82: Bluetooth®, HART

HART, PROFIBUS PA, PROFIBUS DP

plastic

PEEK

plastic

panel

space-saving, directly on sensor

wall, post, panel

certificate of quality

certificate of quality, ex approval, radio
approvalcertificate of quality• 4-wire transmitter• compact device for cabinets• cost-efficient alternative• 2-wire transmitter• easy operation/commissioning• connection via Bluetooth• operation and configuration by the
SmartBlue App• space-saving installation in assemblies• 4-wire transmitter• cleaning via timer, Chemoclean, PID
controller• also suitable for analog sensors

–

23

A

2. Check list
Customer contact data:
Name:

Company:

E-mail:Telephone:
Please fill in

MediumpH range
Conductivity [μS/cm]
Sulfides (S2-), cyanides (CN-), ammonia(NH3) [mg/l]
Hydrofluoric acid (HF) [mg/l]
Organic solvent content [%]Fatty, greasy, sticky media
Suspended solids
Abrasives

Process data

Process temperature
Max. process pressure
Flow velocity

Process connection

Connection type/size

Installation

Ambient temperature
Installation in pipes
Installation in vessel
Bypass installation
Sample preparation

Transmitter

2-/4-wire
Ingress protection
Digital communication (HART, PROFIBUS,
FOUNDATION Fieldbus)
Dosing to be controlled by transmitter?
Automatic cleaning?
Cleaning medium allowed to contaminate
medium?
Multichannel device

Approvals/certificates

Ex (Ex ia, Ex d)
EHEDG
3-A
FDA-listed materialSIL
3.1 certificate

24

From top:
From side:

Notes

A
Customer contact data:
Name:

Company:

E-mail:Telephone:Special demands/short application description/drawing:25

3. Selection of suitable pH sensor
3.1 Flow chart for pH sensor selection

The selection of a pH sensor is primarily based on
chemical and physical behaviors of the process
medium. Combinations with process- or industryspecific requirements like hygienic requirements
will reduce the choice of pH sensors suitable forcertain applications. However, the key criteria
are based on maximum expected lifetime andmaintenance efforts like calibration or refillingof KCl.
There are basically 2 approaches:a)	First choice recommended for a given
applicationb)	Verifying a “known” pH sensor for a new“unknown” application
As some of the conditions might be difficult topredict there is also the choice in the flow chart“unknown”.

ChemicallydemandingHigh risk ofbuild-up

Heavy-duty
applications

Hygienic
applications

Low
conductivity

High organic
loadStandard
application

B

26

From there you are directed to the individual
chapters [3.2 – 3.8] with the indication of
the recommended pH sensor including key
advantages as well as application limits andalternatives. We simplified the flow chart
to reduce complexity. That is why you may
find combinations that require contact withspecialists.

B
START

Temperature < 130 °C
and/orpressure < 17 barabs

yesVerification, if “standard application”• Conductivity > 50 µS/cm• Organic content < 20 vol %• NO fibers, particles or risk of poisoning
e.g. by S2-, CN- or NH3• NOT hygienic or abrasive

yesStandard applications
See page 28

nono

Organic content> 20 % vol. %?

yes orunknown

High organic load
See page 30

noConductivity< 50 µS/cm?

yes

Low conductivity
See page 32

yes

Hygienic applications
See page 34

yes

Heavy-duty applications
See page 36

yesHigh risk of build-up
See page 38

noHygienic requirements?

noAbrasives?

noFibers or particles present?

noContactEndress+HausernoRisk of poisoning e.g. by
S2-, CN-, NH3

yes orunknown

Chemically demanding
See page 40

27

3. Selection of suitable pH sensor
3.2 Application: StandardB
Our proposal

Standard
application

Memosens CPS11E
Orbisint CPS11

Advantages

Memosens CPS16E• Dirt-repellent PTFE junction• Most universal with broad application
spectrum• CPS16E: simultaneous measurementof pH, ORP and rH values for a better
process overview

Technical data
• Process temperature -15 °C to +80 °C (A glass),
0 °C to 135 °C (B glass)
up to 17 barabs• Max. processpressure• pH range• Sensor lengths• Transmission
Application limits‣‣ = alternative
product

28

Memosens CPF81E
Orbipac CPF81• Dirt-repellent PTFE junction• Sensor integrated in plastic holder withthread connection

0 °C to 80 °C (NN version),
0 to 110 °C (LH version)
up to 11 barabs (80 °C)

1 to 12 (A glass), 0 to 14 (B glass)120, 225, 360 and 425 mm
Memosens and TOP68

0 to 14‣‣ liquid-filled 		• Heavily soiling
CPS41/CPS41E
media need spraywith ceramiccleaning –junctionsee assemblyor CPS31E withpage 12 ff.
three ceramic• Slower response ofjunctionssensor with PTFE
junction‣‣ liquid-filled 		• Heavily soiling
CPS41/CPS41E
media need spraywith ceramiccleaning –junctionsee assembly
page 12 ff.
• Slower response of
sensor with PTFE
junction

Memosens, TOP68 and fixed cableApplication: Standard
Process

Typ. liquids• Conductivity > 50 µS/cm• Organic content < 20 vol %• NOT hygienic or abrasive• Neutralization• Water treatment• Water• Wastewater

Memosens CPS41E
Ceraliquid CPS41

Memosens CPS31E
Ceratex CPS31• Fast response time due to ceramic
junction and liquid filling• More soiling-resistant due to continuous
flushing of junction• Fast response time due to ceramic
junction• Less fouling due to silver chloride
filling• For chlorine containing applications
due to special construktion of thereference element-15 °C to 80 °C (A glass),
0 °C to 135 °C (B glass)
up to 11 barabs, CPY7B KCl vessel
with counter pressure necessary-15 to 80°C

2 to 12 (A glass), 0 to 14 (B glass)120, 225, 360 and 425 mm
Memosens and TOP68

1 to 12120 mmMemosens, TOP68 and KOAX

• Manual refillingof electrolyte
vessel CPYB7
necessary• Heavily soilingmedia needed
spray cleaning –see assembly
page 12 ff.

• sensitive tosoiling media
due to small
pores ofceramicjunction‣‣ gel-filled
CPS11/CPS11E
or
CPF81/CPF81E

B
Standard
application

Conditions

up to 4 barabs‣‣ gel-filled
CPS11/CPS11E
or CPF81/
CPF81E29

3. Selection of suitable pH sensor
3.3 Application: High organic loadB
Our proposal
Memosens CPS77E• No aging effect of ISFET chip because oforganics• Stable and fast measurement due toliquid reference• No aging effect of ISFET chip because oforganics• Up to 95 % organic content possible

Technical data
• Process temperature• Max. processpressure-15 °C to 135 °C
up to 11 barabs, KCl vessel CPY7B
with counter pressure necessary-15 °C to 135 °C
up to 11abs bar• pH range• Sensor lengths• Transmission

0 to 14120, 225, 360 and 425 mm
Memosens

0 to 14120, 225, 360 and 425 mm
Memosens• Hot caustics forlong periods e.g.
during “CIP”• Soiling media• Remark: Generally
automatic
cleaning with
Liquiline Control[see page 55]
recommended

High organic
load

Memosens CPS47E

Advantages

Application limits‣‣ = alternative
product

30‣‣ Glass sensor
CPS41E‣‣ CPS41E
and automaticcleaning with
Liquiline Control[see page 55]

Application: High organic load
Process/industry

Typ. liquids• Organic content > 20 vol %• NO fibers, particles or risk ofpoisoning e.g. by S2-, CN- or
NH3• NOT abrasive• Dye and pigment
production• Impregnating resin

B

High organic
load

Conditions31

3. Selection of suitable pH sensor
3.4 Application: Low conductivity

B
Our proposal

Low
conductivity

Memosens CPS11E-xAS
Orbisint CPS11

Memosens CPS41E
Ceraliquid CPS41

With salt storage
Advantages• No electrolyte refilling necessaryTechnical data
• Process temperature-15 °C to 80 °C (A glass)• Fast response time due to ceramic
junction and liquid filling• Extended lifetime because of continuous
electrolyte refilling-15 °C to 80 °C (A glass),
0 °C to 135 °C (B glass)• Max. processpressure

up to 7abs bar

up to 11 barabs, KCl vessel CPY7B
with counter pressure necessary• pH range• Sensor lengths• Transmission

1 to 12 (A glass)120, 225, 360 and 425 mm
Memosens and TOP68

2 to 12 (A glass), 0 to 14 (B glass)120, 225, 360 and 425 mm
Memosens and TOP68• Limited lifetimeof approx. 6months until saltstorage is used up• Manual refillingof electrolyte
vessel necessary• Chance ofcontinuous
outflow of KCl
tracesApplication limits‣‣ = alternative
product‣‣ CPS41/CPS41E

			

32

‣‣ Gel-filled
CPS11/CPS11E
with salt storage‣‣ CPS11/CPS11E

Application: Low conductivity
Process/industry

Typ. liquids• Conductivity < 50 µS/cm• NO fibers, particles or risk ofpoisoning e.g. by S2-, CN- or
NH3• NOT abrasive• Power• Boiler water• Pure/ultra pure
water

B

Low
conductivity

Conditions33

3. Selection of suitable pH sensor
3.5 Application: Hygienic

B
Our proposal
Memosens CPS61E

Hygienic
applications

Advantages

Memosens CPS77E• Non-glass ISFET sensor• “Certificate of compliance” for bio• “Certificate of compliance” forcompatibility available – CIP/SIP resistantbio-compatibility available• Pressurized reference version available for better
resistance against blocking• Upside down version for small fermenters

Technical data
• Process temperature

0 °C to 135 °C-15 °C to 135 °C• Max. processpressure

up to 14 barabs, up to 11 barabs for upside down
version, up to 7 barabs for pressurized reference

up to 11 barabs• pH range

0 to 140 to 14• Sensor lengths• Transmission

120, 225, 360 and 425 mm
Memosens

120, 225, 360 and 425 mm
Memosens‣‣ Risk of glass
breakage• Hot caustics
for long
periods e.g.
during “CIP”• Soiling media

Application limits‣‣ = alternative
product

34‣‣ Non-glass ISFET
sensors CPS77E/
CPS47E‣‣ Retract sensor
during cleaning
cycle or use
CPS61E‣‣ CPS61E and/or ­automaticcleaning[see page 55]

Application: Hygienic
Conditions

Process/industry

Typ. liquids• Organic content < 20 vol %• NOT abrasive• Food• Life sciences• Fermentation• WFI (water for
injection)

Ceramax CPS341D• Non-glass ISFET sensor• Liquid-filled reference to prevent
blocking• Long term stability• Less calibration• Lifetime up to approx. 5 years• Less risk of breakage• Direct mounting in process withhygienic process connection• Fast response• Highly viscous media-15 °C to 135 °C

0 °C to 140 °C

up to 11 barabs, KCl vessel CPY7B withcounter pressure necessary

up to 7 barabs

0 to 140 to 10 (measuring range), 1 to 14(application)–
Memosens

120, 225, 360 and 425 mm
Memosens• Hot caustics forlong periods e.g.
during “CIP”• Soiling media‣‣ Retract sensor
during cleaning
cycle or use
CPS61E, CPS71E‣‣ 	Automaticcleaning [seepage 55] and/or
CPS61E, CPS71E

Hygienic
applications

Memosens CPS47E

B• Manual refilling ‣‣ gel-filled
CPS61E
of electrolyteorvessel necessary
CPS77E• Significantly
higherinvestment costs
than standard
sensor35

3. Selection of suitable pH sensor
3.6 Application: Heavy-duty – abrasiveB
Our proposal
Memosens CPF81E
Orbipac CPF81

Advantages

Technical data
• Process temperature

Heavy-duty
applications• Max. processpressure• pH range• Sensor lengths• Transmission
Application limits‣‣ = alternative
product

36

Memosens CPS97E• Flat membrane prevents glass abrasion• Double chamber reference offers
better protection against poisoning• Sensor design allows mounting ofsensing element in “flow shadow”

0 °C to 80 °C (NN version), 0 to 110 °C(LH version)
up to 11 barabs (80 °C)-15 °C to 110 °C

0 to 14–
Memosens, TOP68 and fixed cable

0 to 14120, 225, 360 and 425 mm
Memosens• Strongly abrasive
particles will
reduce lifetime• Open junctionmeans lessprotection against
poisoning‣‣ ISFET CPS97E

up to 11 barabs‣‣ CPF81/CPF81E

Application: Heavy-duty – abrasive
Process/industry

Typ. liquids• Conductivity > 50 µS/cm• Organic content < 20 vol %• NOT hygienic• Mining• Slurries

B

Heavy-duty
applications

Conditions37

3. Selection of suitable pH sensor
3.7 Application: High risk of build-up

B
Our proposal
Memosens CPS91E
Orbipore CPS91

Advantages

Technical data
• Process temperature• Max. processpressure• pH range• Sensor lengths• Transmission

High risk ofbuild-up

Application limits‣‣ = alternative
product

38

Memosens CPS96E

Memosens CPS11E
Orbisint CPS11

Memosens
CPS16E• Open junction is less prone to blocking• Good poison resistance due to ion trap of
CPS96E or CPS91E “TH version”• CPS96E: Simultaneous measurement of
pH, ORP and rH values for better process
overview• Dirt-repellent PTFE junction• Most universal with broad application
spectrum• Excellent poison resistance due to ion
trap of CPS16E and CPS11E “TA version”• CPS16E: Simultaneous measurement of
pH, ORP and rH values for better process
overview

0 °C to 110 °C
up to 14 barabs-15 °C to 80 °C (A glass),
0 °C to 135 °C (B glass)
up to 17 barabs

0 to 14120, 225, 360 and 425 mm
Memosens and TOP68 (CPS91)

1 to 12 (A glass), 0 to 14 (B glass)120, 225, 360 and 425 mm
Memosens and TOP68 (CPS11)• Extreme risk ofpoisoning• Heavily soilingmedia• With small particle
sizes risk ofblocking‣‣ CPS11/CPS11E
with option “TA”,
CPS16E‣‣ automaticcleaning [seepage 55]‣‣ CPS91/CPS91E,
CPS96E

Application: High risk of build up
Process/industry

Typ. liquids• Conductivity > 50 µS/cm• Organic content < 20 vol %• NOT hygienic or abrasive• Pulp and paper• Process industry• Paper bleaching• Emulsions• Flue gas
desulfurization

B

High risk ofbuild-up

Conditions39

3. Selection of suitable pH sensor
3.8 Application: Chemically demandingB
Our proposal

Advantages

Technical data
• Process temperature

Memosens CPS71E
Ceragel CPS71

Memosens
CPS76E   (TP version)(TP version)

Memosens CPS11E
Orbisint CPS11

Memosens
CPS16E(TA version)• Fast response time without refilling ofelectrolyte• Pressurized reference version for better
resistance against poisoning• CPS76E: Simultaneous measurement of
pH, ORP and rH values for better process
overview• Dirt-repellent PTFE junction• Excellent poison resistance due to ion
trap in the reference• Most universal with broad application
spectrum• CPS16E: Simultaneous measurement of
pH, ORP and rH values for better process
overview

0 °C to 100 °C• Max. processpressure

up to 7 barabs for pressurized reference-15 °C to 80 °C (A glass),
0 °C to 135 °C (B glass)
up to 17 barabs• pH range• Sensor lengths• Transmission

0 to 14120, 225, 360 and 425 mm
Memosens and TOP68 (CPS71)

1 to 12 (A glass), 0 to 14 (B glass)120, 225, 360 and 425 mm
Memosens and TOP68 (CPS11)• Limitations in very
blocking media• Slower responsetime due tomemory effects
of PTFE junction

Application limits

Chemicallydemanding‣‣ = alternative
product

40‣‣ CPS41/CPS41E‣‣ CPS41/CPS41E
orCPS71/CPS71E“TP version”,
CPS76E „TP
version“Application: Chemically demanding
Conditions

Process/industry

Typ. liquids• Risk of poisoning e.g. by S2-,
CN- or NH3• Conductivity > 50 µS/cm• Organic content < 20 vol %• NOT hygienic or abrasive• Batch reactors• Mixture monitoring• Neutralisation• Make up water inchemical industry• Dye and pigment
synthesis• HCN production• Chemical processsolutions

Memosens CPS41E
Ceraliquid CPS41

B• Fast response time due to ceramic
junction and liquid filling• Extended lifetime with outstanding
poison resistance because of continuous
reference refilling-15 °C to 80 °C (A glass),
0 °C to 135 °C (B glass)
up to 11 barabs, KCl vessel CPY7B withcounter pressure necessary
1 to 12 (A glass), 0 to 14 (B glass)120, 225, 360 and 425 mm
Memosens and TOP68‣‣ gel-filled
CPS11 “BT version, CPS11E“TA version“,
CPS16Eor
CPS71/CPS71E“TP version”,
CPS76E „TP
version“Chemicallydemanding• Manual refilling ofelectrolyte vessel
necessary41

4. Selection of assembly
4.1 Flow chart for assembly selection

General considerations
Correct assembly selection requiresconsideration of the installation and application
conditions as well as pH sensor selection.

For chemically demanding and safety relevant
applications, ball-valve sealed assemblies
should be preferred due to complete mechanicalisolation during exchange process.
Manual retraction of assemblies with a sliding
drive is only possible up to 2 bar process pressure,manual assemblies with rotary drive can beretracted at pressures up to 8 bar although theassemblies are suitable for higher pressuresduring normal operation. For retraction at ahigher pressure you need a pneumatic version.
Same holds true for automatic measuring,cleaning and calibration. In case you want to use
our Liquiline Control or Chemoclean Plus please
select a pneumatically driven retractable assembly
as most manual versions can not be converted.

Retractableassembly withball valve

Retractableassembly withpiston sealing

Fixed
installation

Immersion­­t ypeC

Please be aware that several retractableassemblies are available in different versions
suitable for either gel or liquid-filled sensors.
Retrofitting from one version to another is either
impossible or needs a lot of effort. Make surethat you select an assembly which fits with the
pH sensor. See table 4.6 on page 48 for details.

42

When using 2 Memosens pH sensors for ameasuring point - one in the application andthe 2nd one the calibration / recovery cycle,
retractable assemblies or bypass installations
are required to enable exchange of pH
sensors without interrupting the process.
In case of hygienic applications, theselection is based on process requirements(e.g. ..., you will find corresponding
recommendations in the different sections).

C

START

Installationin open channels or in(pressurized) vessels
from top?

Yes

Immersion type
See page 44

Yes

Fixed installation
See page 46

No

Retractable assemblywith piston sealing
See page 48

No
No removalof pH sensor during
operation required?

No
Chemicallydemanding or hygienic
application?

No
ContactEndress+Hauser

No

Abrasives,
fibers, particles present
or high availability
required?

Yes

Maintenanceof the assembly required
while the process
is running?

Yes
Yes

43

Retractable assemblywith ball valve
See page 50

4. Selection of assembly
4.2 Immersion type

Our proposal
Flexdip CYA112

Dipfit CPA111• Modular system for different kinds ofmounting e.g. exchangeable for one pHor turbidity sensor• 3 sensor slots for redundantmeasurement• Flexible immersion depth by chemicallyresistant pipes• Spray cleaning head as option

0 to 60 °C
1 barabs-10 to 80 °C
1 to 5 barabs

PVC; stainless steel 1.4404/316L, EPDM

Polypropylene (PP), EPDM

Different holder systems, float ball,chain from Nylon hanging, pendulum
frame mounting
600 to 3600 mm

Flange DN 100, adjustable flange DN100, hanging bracket• Long immersion
depth or version
for high lateralload like agitation
on request• Pressurization• High lateral load
like agitation

Immersion­­t ypeC

Advantages

Technical data
• Process temperature• Max. processpressure• Material of wettedparts• Process connection• Immersion depth
Application limits‣‣ = alternative
product

44‣‣ CPA111‣‣ CPA140

500 to 3000 mm‣‣ CPA140

Installation in open channels, basins andin closed vessels from top
Immersion assemblies are usually used for installation in open channels
and basins fixed by chains or on a rail. Versions with flanges can as wellbe used for installation of the sensor from the top of a vessel. Typicalapplications are e.g. municipal and industrial wastewater.

Dipfit CPA140

Immersion­­t ypeC• 3 sensor slots for redundantmeasurement• Robust process sealing thanks to thebayonet mounting method-10 to 150 °C
1 to 11 barabs
PVDF, stainless steel 1.4404/316L,
EPDM, FKM, FFKM
Flange DN 80, ANSI 3” and JIS
500 to 2500 mm• Service-friendly
change of sensor‣‣ retractable
CPA450 or
CPA47345

4. Selection of assembly
4.3 Fixed installation

Our proposal: Standard
Flowfit CYA21

Flowfit CPA250• Compact design; ideal for limited space
applications• Compatible with common tube fitting
systems• 3 sensor slots for redundantmeasurement• Polypropylene (PP) flow through type
• Easy calibration by detachable
calibration vessel

0 to 100°C
1 to 17 barabs

0 to 80 °C
1 to 7 barabs

Stainless steel 1.4404/316L

Polypropylene (PP), EPDM

• Process connection

Pipe 6mm (OD)

Thread G1, NPT 1”• Immersion depth

–

–

Fixed
installation

C

Advantages

Technical data
• Process temperature• Max. processpressure• Material of wettedparts

Application limits‣‣ = alternative
product

46• Redundant measurements, highflow capacity‣‣ CPA240• Installation intank or vessel• Temperature> 80 °C‣‣ CPA640 or
CPA842‣‣ CPA240, CYA21

Installation in pipes/bypass with flow through orinsertion type assembly
Suitable for processes which do not need frequent replacement
or calibration of pH sensors. For applications with pressure in pipe medium
flow has to be interrupted in the pipe or bypass to get access to the sensor by
an external valve.
Our proposal: hygienic
Unifit CPA842

Ecofit CPA640• 3 sensor slots for redundantmeasurement• Different design (axis) of inlet andoutlet of the fluid available• Variety of process connections• Effective solution especially for batchprocesses• Design follows up-to-date hygienic
engineering guidelines such as ASME
BPE, EHEDG or 3-A• Adapter to G or NPT threadconnections-10 to 150 °C
1 to 11 barabs-15 to 140 °C
1 to 17 barabs-10 to 140 °C
1 to 7 barabs

PVDF, 316L, FKM, FFKM

Stainless steel 1.4435/316L, EPDMFDA, FKM-FDA, FFKM-FDA, siliconeFDA
Thread G 1¼”, NPT, Tri-Clamp, Varivent,
DN 25 and DN 50 dairy fitting
Aseptic fitting DN50 thread
DIN11864-1A

PVDF, stainless steel 1.4404/316L or
stainless steel 1.4435/316L, EPDM,
FKM, FFKM
Thread G 1¾” or M25x1.5, NPT ½”, ¾”–

25 mm, 50 mm or 85 mm

Thread or flanges DN 25; 90° or 180°
between in- and outflow–• Large dimension
e.g. panels in
power stations• Change of sensor
under pressure‣‣ CYA21‣‣ retractable
CPA871• Change of sensor
under pressure
in hygienic
design‣‣ retractable
CPA875• Only thread
processconnections‣‣ CPA842

47

C

Fixed
installation

Flowfit CPA240

4. Selection of assembly
4.4 Retractable assembly (with piston sealing)

C

Retractableassembly withpiston sealing

Advantages

Technical data
• Process temperature• Max. processpressure• Material of wettedparts• Process connection• Immersion depth
Application limits‣‣ = alternative
product48

Our proposal: Standard

Our proposal: hygienic

Cleanfit CPA871

Cleanfit CPA875• Flexible retractable assembly for a broad
range of applications• Intelligent functions for highest process
and personnel safety• Hygienic design 3-A, FDA-listed
materials and EHEDG certificate for abroad range of hygienic applications• Double chamber with patented sealing
principle for 100% sterile processes-10 to 140 °C (PVDF: -10 to 100 °C)
manual: 1 to 9 barabs, pneu.: 1 to 17 bar abs-10 to 140 °C
manual: 1 to 9 barabs, pneu: 1 to 17 barabs

Stainless steel 1.4404/316L, PEEK,
Alloy C22, PVDF
Seals: EPDM, FKM, FFKM
G 1¼”, NPT 1½”, Tri-clamp, dairy fitting,flanges

Stainless steel1.4435/316L

up to 135 mm• Mechanicalstability• Soiling media(fibers)‣‣ CPA472D‣‣ CPA473, CPA450

G 1¼”, Tri-clamp, aseptic, Neumo
Biocontrol, Neumo Bioconnect, dairy
fitting, Varivent flange
up to 80 mm• Relatively highinvestment costs‣‣ Fixed
installation
with CPA842

Installation in pipe and vessels withpiston sealing towards process
Manual and pneumatic

Our proposal: Heavy-duty
Cleanfit CPA472D

C

Retractableassembly withpiston sealing• Various materials available for best chemical compatibility• Heavy-duty version available with flowchamber and sight glass as option• High immersion depth up to 280 mm-20 to 140 °C
1 to 11 barabs
Stainless steel 1.4571/316L, Alloy C22, PVDF,
PVDF conductive, PEEK
G 1¼”, flanges DN 50/80, ANSI 2” JIS
up to 280 mm• Relatively high investment
costs‣‣ CPA450

49

4. Selection of assembly
4.5 Retractable assembly (with ball valve)

C

Retractableassembly withball valve

Advantages

Technical data
• Process temperature• Max. processpressure• Material of wettedparts• Process connection• Immersion depth• Operation
Application limits‣‣ = alternative
product50

Our proposal: manual

Our proposal: pneumatic

Cleanfit CPA450

Cleanfit CPA473• Variable immersion depths up to 700 mm• Open sensor protection guard preventsfibers from sticking round the sensor• Safety kit to protect of higher
pressure• Open sensor protection guard and tapewiper prevents fibers from sticking
round the sensor e.g. media in pulp &paper, mining

0 to 130 °C
1 to 5 barabs retraction;
1 to 17 barabs static
SS 316L and Hastelloy C22, titanium,
EPDM, FKM, FFKM
G 1¼”, G 1½” NPT ½”, flanges DN 32,
ANSI 1½” and 2”
3 types: from 100 up to 700 mm
manual0 to 100 °C
1 to 7 barabs• Not for KClelectrodes• Insertion onhigher pressure
4 to 10 bar• Remark:
For sticky andabrasive medium
choose “tapewiper option”‣‣ CPA473

SS 316L, FKM, FFKM
G 1¼”, dairy DN 50, flanges DN 50/ANSI
up to 230 mm
manual/pneumaticInstallation in pipes and vessels withball valve• Ball valve offers safety process sealing• Manual and/or pneumatic

Cleanfit CPA451• Suitable for aggressive medium• Open sensor protection guard and tapewiper prevents fibers from sticking
round the sensor e.g. media in pulp &paper, mining• Suitable for CPF81/CPF81E• Open sensor protection guard
prevents fibers from sticking roundthe sensor

0 to 120 °C
1 to 7 barabs

0 to 80°C
1 to 3 barabs retractions;
1 to 11 barabs static
Stainless steel 1.4404/316L

Polypropylene (PP), PVDF, PEEK,EPDM, FKM, FFKM
G 1¼”, dairy DN 50,
flanges DN 50/ANSI
up to 207 mm
manual/pneumatic• PP/PVDF/PEEK
chemically notcompatible‣‣ CPA473

C

Retractableassembly withball valve

Cleanfit CPA474

G2“ female, flange DN50 Iso 1092-1,
flange 2“ ANSI
up to 270mm
manual• Chemical
resistivity,
specifications‣‣ 12 mm sensor
with another
Cleanfitassembly51

4. Selection of assembly
4.6	Required pH sensor length and immersion depth
for various assemblies
Maximum
immersion
depth2)

C

Glass sensors
CPS11/CPS11E/CPS16ECPS41/CPS41E 1)

CPS71/CPS71E/
CPS76E

CPS91/CPS91E/CPS96E

120 mm

120 mm

CPA111

see note 3)

120 mm

120 mmCYA112

see note 3), 5)

120 mm–

120 mm

120 mm

CPA140see note 3)

120 mm

120 mm

120 mm

120 mm

CPA240not applicable

120 mm

120 mm

120 mm

120 mm

CYA21

not applicable

120 mm

120 mm

120 mm

120 mm

CPA250not applicable

120 mm

120 mm

120 mm

120 mm

CPA84273 mm

120 mm

120 mm

120 mm

120 mm

CPA64085 mm

120 mm

120 mm

120 mm

120 mm
120 mm

CPA450
CPA472D

CPA473

CPA474CPA871

CPA87552

see note 3)

120 mmn/a

120 mmshort

146 mm

225 mm

360 mm

225 mm

225 mmlong

280 mm

360 mmn/a

360 mm

360 mmshort

100 mm

225 mm

425 mm

225 mm

225 mmlong

230 mm

360 mmn/a

360 mm

360 mm

short

76 mm

225 mm

425 mm

225 mm

225 mmlong

207 mm

360 mmn/a

360 mm

360 mmbasic short

36 mm

120 mm *4)n/a

120 mm

120 mmbasic long

78 mm

225 mm

225 mm

225 mm

225 mmimmersionchambershort

135 mm

225 mmn/a

225 mm

225 mmimmersionchamberlong

187 mm

360 mm

360 mm

360 mm

360 mmsinglechamber
short

36 mm

225 mm

225 mm

225 mm

225 mmsinglechamber
long

78 mm

225 mm
360 mmn/a
360 mm

225 mm
360 mm

225 mm
360 mmdoublechamber

78 mm

225 mm
360 mm
360 mmn/a
360 mmn/a

225 mm
360 mm
360 mm

225 mm
360 mm
360 mmISFET
CPS47E 1)

CPS77ECPS97E

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mm

120 mmn/a

120 mm

120 mm

360 mm

225 mm

225 mmn/a

360 mm

360 mm

425 mm

225 mm

225 mmn/a

360 mm

360 mm

425 mm

225 mm

225 mmn/a

360 mm

360 mmn/a

120 mm

120 mm

225 mm

225 mm

225 mmn/a

225 mm

225 mm

360 mm

360 mm

360 mm

225 mm

225 mm

225 mmn/a
360 mm

225 mm
360 mm

225 mm
360 mmn/a
360 mmn/a

225 mm
360 mm
360 mm

225 mm
360 mm
360 mmMax. length
see note 2)

C
Notes:
1) Liquid-filled [KCl]2)	The indicated length is the maximum length
which must be considered e.g. for installationin pipes to ensure mechanical space;depending on process connection it may be
shorter for the individual assembly(see drawing)3) Depending on length of immersion assembly
4) Not CPS16E
5) CPF81E can be combined with CYA112
or CPA451

53

5. Life cycle management of pH measuring loops
5.1 Optimum calibration concept for the lab thanks to Memosens andMemobase Plus
Important maintenance measures such as sensor
calibration can then take place in the comfortablesurroundings of the laboratory – under constantand perfect conditions and with all of the necessary
tools available there. This is much faster than at
the site where the sensor is used in the process.

With Memosens technology, analog signals areconverted to digital signals directly in the sensor.
This is why the sensor is also the only component
that must be checked and calibrated regularly.
The cable and transmitter do not affect themeasured value unlike in an analog system which
can be sensitive to moisture and electromagnetic
interferences.

The Memobase Plus software acts as the perfectcomplement to support the concept of laboratory
calibration. This sensor and data management
software allows you to calibrate and check yoursensors very easily. Furthermore, Memobase
Plus saves all sensor and calibration data in a
database allowing you to create visualizations andreports automatically and export data. In addition
to pH glass sensors and pH ISFET sensors, thesoftware supports sensors for ORP, conductivity
and dissolved oxygen. Memobase Plus is available
in 12 languages and linked to Endress+Hauser’s
W@M Portal. This enables professional life
cycle management of all the sensors used in theprocess.

Memosens sensors not only determine andtransfer the measured value but also save
additional process data. This data can include
operating hours at higher temperatures, forexample, or maximum temperatures occurring in
the process. This information enables predictive
maintenance. In addition, current calibration datasuch as the slope and zero point of the pH sensor
are also saved. Using Memosens technology, you
can therefore replace the sensor quickly and easily
in the process with a clean, ­­pre-calibrated sensor.
The measured value controlling your process isthus available immediately once again.

Fully traceable documentation:
Life cycle of Memosens sensors

to

tory
ora
lab

clean
ing
/re
g

io

processn

Memobase Plus

54

en
er
at

5.2 Fully automatic measuring, calibration and cleaning

Liquiline Control
If it’s a case of upgrading a manual measuring
point to a fully automated pH system, you willfind the ideal solution in Liquiline Control CDC90.
The system ensures continuous maintenance ofthe sensors. This guarantees a high degree of
accuracy and the highest degree of availability ofyour pH measuring point. Thanks to its web-based
technology, Liquiline Control CDC90 supports
remote access from anywhere at any time –directly via your process control systems or any
mobile device such as tablets, smartphones ornotebooks.

Liquiline Control CDC90
Fully automatic pH
measuring pointwith integrated
control• Calibration• Cleaning• Rinsing

Liquiline with Chemoclean Plus
The Liquiline multiparameter transmitter with
Chemoclean Plus is the variable solution forautomatic sensor cleaning. Liquiline features
four independent relays to control a retractableassembly and cleaner supply. The system is
supplemented by a compact valve block thus
offering the flexibility of a multichannel device
together with the option of automaticallycleaning the connected sensors.

Liquiline CM44 with ­C hemoclean Plus

Transmitter with ­C hemoclean Plus

Cleanfit Control

Retractableassembly

Cleaning ­solution

pH sensor

55

5. Life cycle management of pH loops
5.3 Lifetime of pH sensors

You might be wondering why there are so manydifferent pH sensors and options available.
The problem lies in the measuring principle.
On the one hand the sensing element, glassor ISFET (ion selective field effect transistor)
is directly in contact with the medium. Any
deposits, abrasive particles, mechanical stressand aggressive chemicals will have an impact on
the measurement accuracy and/or lifetime of thesensor. Additionally, the junction of the pH sensor
brings the reference system in direct contact
with the medium. Ions which react with the silverreference wire like e.g. sulfides and cyanides
can destroy the reference system. Blockage of56

the junction would interrupt the measurementand dilution of the reference solution changes
the potential of the reference system. The latter
effect is the reason why a pH sensor has to becalibrated and adjusted regularly. Problems withwet connectors or ground leaks are not any longer
an issue with Memosens technology.
There is no reasonable answer to the question:
What is the lifetime of the sensor? Sensor lifetime
depends on sensor choice, cleaning intervals
and of course your application. pH sensors havetherefore to be considered as consumables.

5.4 Accreditation for		permanent pH buffer		laboratory
Correct measurement of the pH value not only
serves to ensure that limit values are adhered to,
but the pH value is also often used as a reference
variable for product quality or used directlyfor control purposes. The requirements for pH
measurement are extremely tough, and thisapplies across the entire measuring range of 14
orders of magnitude. Measurement accuracy
and reproducibility begin and end with correct
calibration of the pH measuring point.
For calibration, pH buffer solutions are usedworldwide across all sectors. The zero point andslope of a pH sensor are important reference
variables for the quality of a pH measurement.
These are calculated using two different pH
buffer solutions.

The accuracy of the later pH measurement in theprocess is directly dependent on the quality andaccuracy of the specified pH value of the pH buffer
solutions. For many years now, Endress+Hauser
Conducta has been manufacturing quality buffers
for the following pH values: 2.00, 4.00, 7.00, 9.00,
9.22, 10.00 and 12.00. They meet even the toughrequirements of the life sciences industry andcontain only FDA-listed preservatives.

Endress+Hauser Liquid Analysis underwent the
DKD’s demanding accreditation procedure inaccordance with DIN EN ISO/IEC 17025:2005.
On May 5, 2009, the accreditation body granted
the authority to issue calibration certificates for
pH buffer solutions. On August 31, 2020, theaccreditation body renewed the accreditation
for the permanent calibration laboratory in
Waldheim, Saxony with the DAR registration
number D-K-15193-01.
The accreditation is regularly repeated andconfirms that the actual values and maximum
deviations of the manufactured pH buffer
solutions are determined in a manner that iscorrect and traceable. In the measuring rangeof pH 2 – 10, the smallest specifiable measuring
uncertainty of 0.02 applies. In the measuring
range of pH > 10 – 12.5, the smallest specifiablemeasuring uncertainly of 0.05 applies. Thismeans that customers can rely completely on
Endress+Hauser’s pH quality buffers. Users fromall industrial sectors benefit from the reliability ofthese calibration solutions.

57

5. Life cycle management of pH loops
5.5 Steam/water analysis systems

Steam production consumes a high amount ofenergy within industrial processes. The usage ofhigh quality water in boiler applications of power
plants and utility departments prevents corrosion
processes and build-up. This ensures keeping theboiler efficiency high and therefore contributes toenergy saving.

58

Endress+Hauser offers the full scope ofequipment for the analysis of pure water for suchboiler applications. As pressure and temperature
are in most cases too high to measure directlyin the process a sample conditioner is needed in
front of the analytical panels. This is as well in
the Endress+Hauser offering.

Notes59

Supplementary documentation• Parameter overview
FA00007C/07/en
Products

Solutions

Services

Experts in Liquid Analysis

Sensors, transmitters,compact devices and assemblies
Experts in Liquid Analysis

Links• Application Selection Software
www.endress.com/applicator• Overview of all components
www.endress.com/pH• Memosens technology
www.endress.com/memosens• Liquiline Control CDC90
www.endress.com/CDC90

CP00010C/07/en/16.21

www.addresses.endress.com