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Dissolved oxygen transmitter Liquisys COM253

Compact field device for water, wastewater, utilities and fish farming

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Dissolved oxygen transmitter Liquisys COM253

Compact field device for water, wastewater, utilities and fish farming

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Benefits

  • More operational safety: Continuous process check system, customized alarm configuration, calibration plausibility check.
  • Reliable oxygen control: Current input for flow rate monitoring with controller shut off or for feedforward control.
  • Easy to operate and service: Simple single-point calibration in air, air-saturated water or in the medium, direct access for manual contact control.
  • Reduced maintenance: Automatic cleaning function (with Chemoclean) triggered by alarm or limit switch.
  • Fit for every application: Numerous extensions, e.g. P(ID) controller, timer, etc., allow for flexible adaption to all processes.
Manufacturer's warranty

Engineered for confidence

Our instruments are designed for long‑lasting performance, precise measurement, and dependable operation in demanding industrial environments. Each product includes a standard manufacturer’s warranty that reflects our commitment to quality and to the trust you place in our solutions.

Should a warranty case occur, the device will be assessed and the applicable remedy will be provided in line with the warranty terms – helping ensure a reliable and efficient resolution and supporting continued operation of your measurement point.

Request for extended warranty

If you require extended warranty coverage, simply contact your local Endress+Hauser representative. Our experts will advise you on the available options to match your application and risk profile, helping you protect your investment, reduce unexpected repair costs, and ensure reliable long‑term operation beyond the manufacturer's warranty period.

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Warranty terms apply

The manufacturer's warranty and extended warranty are subject to specific conditions. For full details, please refer to the locally applicable General Terms and Conditions (GTC), which can be found on the respective country page of our website.

Services by your side

Right‑first‑time commissioning, worldwide

Endress+Hauser’s qualified service engineers ensure your measurement devices are commissioned right the first time, delivering application‑aligned accuracy, regulatory compliance, and operational confidence from startup onwards, anywhere in the world.

Remote support you can trust wherever you operate

With Endress+Hauser Smart Support, you benefit from faster issue resolution, higher uptime, reliable global expertise across the entire product lifecycle – and lasting peace of mind.

Committed to long‑term, sustainable performance

With deep field expertise, harmonized processes, and continuous monitoring, we accompany you with comprehensive service offerings – from initial start‑up through instrumentation maintenance to process optimization – as a true lifetime partner delivering improved outcomes.

For additional information, please contact your local Endress+Hauser representative.

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Product information

Liquisys COM253 is a compact field transmitter for dissolved oxygen measurement.
Dissolved oxygen field transmitter
Specifications
Measuring / Application task Oxygen
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Description

Liquisys COM253 is a standard transmitter for use with COS41 and COS61 oxygen sensors. It improves your operational safety thanks to continuous plausibility, process and sensor checks. Select from numerous hardware and software modules, such as relays or fieldbus communication, to adapt it exactly to your measuring task. This modularity also allows you to upgrade the transmitter at any time. A simple menu and calibration make configuration and operation fast and easy.

Field of application

The Liquisys COM253 transmitter works with Oxymax COS41 and Oxymax COS61 dissolved oxygen sensors in environmental applications, such as:

  • O2 control in the aeration basin
  • O2 control and monitoring of drinking water
  • Surface water monitoring
  • Process water treatment and monitoring
  • O2 control in fish farming for optimum growth conditions

Liquisys COM253 features the following protocols and interfaces:

  • 0/4...20 mA
  • HART
  • PROFIBUS DP
  • PROFIBUS PA
Benefits
  • More operational safety: Continuous process check system, customized alarm configuration, calibration plausibility check.
  • Reliable oxygen control: Current input for flow rate monitoring with controller shut off or for feedforward control.
  • Easy to operate and service: Simple single-point calibration in air, air-saturated water or in the medium, direct access for manual contact control.
  • Reduced maintenance: Automatic cleaning function (with Chemoclean) triggered by alarm or limit switch.
  • Fit for every application: Numerous extensions, e.g. P(ID) controller, timer, etc., allow for flexible adaption to all processes.
Predecessors
COM141S, COM240S, COM340, COM141, COM130, COM140, COM240, COM151, COM252
Downloads
Most downloaded
Technical Information (TI)
Liquisys M COM223/253 Technical Information Transmitter for oxygen sensors
English version - 12/2014
Download
Operating Instruction (BA)
Operating Instructions Liquisys M CXM223/253 PROFIBUS Field Communikation for Liquisys M CXM223/253
English version - 12/2011
Download
Operating Instruction (BA)
Liquisys M COM223/253 Operating Instructions Transmitter
English version - 09/2015
Download
The CAD Drawings will be available after the configuration.
All downloads
25 Downloads
Technical Information (TI)
Most downloaded
Liquisys M COM223/253 Technical Information Transmitter for oxygen sensors
English version - 12/2014
Download
Operating Instruction (BA)
Most downloaded
Operating Instructions Liquisys M CXM223/253 PROFIBUS Field Communikation for Liquisys M CXM223/253
English version - 12/2011
Download
Operating Instruction (BA)
Liquisys M COM223/253 Operating Instructions Transmitter
English version - 09/2015
Download
Operating Instruction (BA)
Operating Instructions Liquisys M CXM223/253 HART Field Communication with Liquisys M CXM223/253
English version - 10/2005
Download
Operating Instruction (BA)
Model 840 / 842 Operating instructions Transmitter for dissolved oxygen
English version - 07/2002
Download
Short Instruction (KA)
KA Liquisys M COM253 Transmitter for dissolved oxygen
English version - 10/2025
Download
Installation Instructions (EA)
EA Liquisys M CxM223/253 and Smartec S CLD132/134 Central modules
English version - 09/2026
Download
Ex Safety Instruction (XA)
Ex-safety instructions CXM2X3 Safety instructions for electrical apparatus for explosion-hazardous
areas as per EC Directive 94/9/EC (ATEX)
English version - 06/2005
Download
Special Documentation (SD)
Instructions for service kits Liquisis M Special documents
Instructions for service kits Liquisis M / CPM253 / CLM253 / COM253 /
CUM253
English version - 05/2000
Download
Special Documentation (SD)
Additional information for CSA Liquisys Additional information for CSA Liquisys
English version - 09/2013
Download
Special Documentation (SD)
Installation of M 12 plug Special Documentation Installation of M 12 plug
CPM253 / COM253 / CLM253 / CUM253
English version - 10/1999
Download
Manufacturer Declaration
Product family: Liquisys oxygen Product root: COM253-
Declaration number: HE_02110_01.25
Manufacturer specification: RoHS
Additional information: China-RoHS
English version - 04/2025
Download
EU Declaration
Product family: Liquisys chlorine, Liquisys conductivity, Liquisys oxygen, Liquisys pH/ORP Product root: CCM223-, CCM253-, CLM223-, CLM253-, COM223-, COM253-, CPM223-, CPM253-
Declaration number: EC_00575_02.23
English version - 07/2023
Download
UK Conformity Assessed
Product family: Liquisys chlorine, Liquisys conductivity, Liquisys oxygen, Liquisys pH/ORP Product root: CCM223-, CCM253-, CLM223-, CLM253-, COM223-, COM253-, CPM223-, CPM253-
Declaration number: UK_00563_01.23
Additional information: UK DoC for C*M2*3
English version - 07/2023
Download
Product Carbon Footprint Information
Product family: Liquisys oxygen Product root: COM253-
Declaration number: ED_00197_01.24
English version - 11/2024
Download
Miscellaneous
Product family: Liquiline, Liquiline M, Liquisys chlorine, Liquisys oxygen, Liquisys pH/ORP Product root: CCM223-, CCM253-, CM14-, CM42-, CM442-, CM442R-, CM444-, CM444R-, CM448-, CM448R-, CM44P-, CM72-, CM82-, COM223-, COM2
53-, CPM223-, CPM253-
Region: Eurasian Economic Union
Approval agency: EAC
Approval number: EAEC KZ 7500525.13.12.00621
Russian version - 02/2025
Download
Miscellaneous
Product family: Liquiline, Liquiline M, Liquisys chlorine, Liquisys oxygen, Liquisys pH/ORP Product root: CCM223-, CCM253-, CM14-, CM42-, CM442-, CM442R-, CM444-, CM444R-, CM448-, CM448R-, CM44P-, CM72-, CM82-, COM223-, COM2
53-, CPM223-, CPM253-
Region: Eurasian Economic Union
Approval agency: EAC
Approval number: ЕАEС KZ 7500525.13.12.00639
Russian version - 02/2025
Download
Ordinary Location Product Safety
Product family: Liquisys chlorine, Liquisys conductivity, LIQUISYS M, Liquisys oxygen, Liquisys pH/ORP, Liquisys turbidity, SmarTec S Product root: CCM223-, CCM253-, CLD134-, CLM223-, CLM223F-, CLM253-, COM223-, COM223F-, COM253-, COM253F-, CPM223-, CPM253-, CUM223-
, CUM253-
Region: Canada/USA
Approval agency: CSA
English version - 04/2018
Download
Tender Text
Liquisys COM253 Sauerstoff- und Temperatur Messumformer
German version - 12/2016
Download
General Station Description (GSD)
General Station Description (GSD) - Liquisys Oxygen - PROFIBUS DP Any, PROFIBUS System, Any
Language neutral - 11/2023
Download
General Station Description (GSD)
General Station Description (GSD) - Liquisys Oxygen - PROFIBUS PA Any, PROFIBUS System, Any
Language neutral - 11/2023
Download
Device Type Manager (DTM)
Device Type Manager (DTM) - Liquisys Oxygen - PROFIBUS DP Endress+Hauser, DeviceCare, 1.07.06
Language neutral - 07/2026
Download
Device Type Manager (DTM)
Device Type Manager (DTM) - Liquisys Oxygen - PROFIBUS PA Endress+Hauser, DeviceCare, 1.07.06
Endress+Hauser, Field Xpert - SMT70, 1.07.00
Endress+Hauser, FieldCare, 2.17.00
Language neutral - 11/2023
Download
Device Type Manager (DTM)
Device Type Manager (DTM) - Liquisys Oxygen - PROFIBUS PA Endress+Hauser, DeviceCare, 1.07.06
Language neutral - 07/2026
Download

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Liquisys COM253 is a compact field transmitter for dissolved oxygen measurement.
Dissolved oxygen field transmitter

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Dissolved oxygen field transmitter
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Spare parts and accessories

further parts
further parts

Kit CXM2X3 Relaismod. 2rel

further parts
further parts
Order code 51500320
further parts
further parts

KIT CXM2X3 relay mod. 2rel / CSA

further parts
further parts
Order code 51511446
Drawing number 290
further parts
further parts

Kit CXM2X3 Relaismodule 4rel

further parts
further parts
Order code 51500321
Drawing number 300
further parts
further parts

KIT CXM2X3 relay mod. 4rel / CSA

further parts
further parts
Order code 51511447
Drawing number 300
Spare parts and accessories

Selection of compatible products

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