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

Dissolved oxygen transmitter
Liquisys COM253

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

COM253

Compare

Specs at a glance

Input

1-channel transmitter.
Output / communication

0/4-20mA, Hart, Profibus.

See all specifications

Field of application

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.

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.

Predecessor

COM141S
COM240S
COM340
COM141
COM130

COM140
COM240
COM151
COM252

Success stories

50% less precipitant - 100% reliability and cooperation

IDEA achieved tremendous cost savings through continous monitoring with the CA80PH Analyzer at their site in Wallonia
Read the full story
An automated system for pH measurements at AVR

AVR Waste in Botlek, Rotterdam, processes up to 1.7 million tons of residual waste per year. Discover how they optimized their pH measurement thanks to Endress+Hauser
Read the full story
Safe phosphate elimination with minimal effort

Thanks to Endress+Hauser the Wastewater treatment plant in Breuberg meets legal requirements and ensures safe phosphate elimination.
Read the full story
Toilet flushing with a fresh sea breeze

Using seawater to flush toilets can save a lot of drinking water. To ensure a constant water supply, the sensors used must function reliably to meet the water quality objectives (WQO).
Read the full story
Monitoring biological parameters in wastewater

Examination of wastewater, using the Liquistation CSF48 and the Liquiport CSP48 mobile, can provide valuable information about the occurrence of Covid 19 infections in a specific area
Read the full story

Simple products
Easy to select, install and operate

Technical excellence

Simplicity

What is FLEX?

Standard products
Reliable, robust and low-maintenance

Technical excellence

Simplicity

What is FLEX?

High-end products
Highly functional and convenient

Technical excellence

Simplicity

What is FLEX?

Specialized products
Designed for demanding applications

Technical excellence

Simplicity

Variable

What is FLEX?

FLEX selections	Technical excellence	Simplicity
F L E X Fundamental selection Meet your basic measurement needs	Technical excellence	Simplicity
F L E X Lean selection Handle your core processes easily	Technical excellence	Simplicity
F L E X Extended selection Optimize your processes with innovative technologies	Technical excellence	Simplicity
F L E X Xpert selection Master your most challenging applications	Technical excellence	Simplicity Variable

Learn more about the FLEX selections

	EN	More
31/12/2014
24/10/2013
20/06/2011
11/09/2005
01/07/2005

Language:	English
Version:	31/12/2014
File size:	822 KB
File name:	TI00199CEN_1514.pdf

	EN	More
01/12/2011
01/08/2009
01/09/2007
01/07/2006
01/10/2005

Language:	English
Version:	01/12/2011
File size:	1.7 MB
File name:	BA209CEN_1311.pdf

	EN	Select other language
31/12/2014
24/10/2013
20/06/2011
11/09/2005
01/07/2005

	EN	Select other language
01/09/2015
24/10/2013
20/06/2011
15/09/2005
01/07/2005

Language:	Russian
Version:	06/02/2025
File size:	1.3 MB
File name:	KZ 7500525.13.12.00621.pdf

Language:	German
Version:	20/12/2016
File size:	25 KB
File name:	TTCOM253DE.doc

File size:	48.6 KB
File name:	EH_PA_AN_Liquisys_0x1518_V02_00_PALIB.zip
Device Type:	0x1518
Firmware:	2.491
Version:	2.00.00
Date:	22/04/2014

File size:	48.1 KB
File name:	EH_DP_AN_Liquisys_0x151E_V02_04_DPLIB.zip
Device Type:	0x151E
Firmware:	2.491
Version:	2.04.00
Date:	14/04/2014

File size:	227.4 MB
File name:	EH_Liquisys_M_COM_2x3_PA_V2_40__V2_41.zip
Device Type:	0x1518
Firmware:	2.491
Version:	1.5.153.348
Date:	15/05/2023

File size:	228 MB
File name:	EH_Liquisys_M_DO_COM_2x3_V2_40.zip
Device Type:	0x0094
Device Revision:	1
Firmware:	2.47
Version:	1.4.188.39
Date:	12/05/2023

	EN	Select other language
07/06/2005
27/09/2004
29/02/2004

Dissolved oxygen transmitter Liquisys COM253

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

Specs at a glance

Input

Output / communication

Field of application

Benefits

Predecessor

Success stories

50% less precipitant - 100% reliability and cooperation

An automated system for pH measurements at AVR

Safe phosphate elimination with minimal effort

Toilet flushing with a fresh sea breeze

Monitoring biological parameters in wastewater

Measuring principle

Application

Characteristic

Design

Material

Dimension

Temperature sensor

Input

Output / communication

Additional certifications

Back

Liquisys M COM223/253 Technical Information

Operating Instructions Liquisys M CXM223/253 PROFIBUS

Liquisys M COM223/253 Technical Information

Operating Instructions Liquisys M CXM223/253 PROFIBUS

Model 840 / 842 Operating instructions

Liquisys M COM223/253 Operating Instructions

Operating Instructions Liquisys M CXM223/253 HART

Ex-safety instructions CXM2X3

Instructions for service kits Liquisis M

Installation of M 12 plug

Additional information for CSA Liquisys

Product family: Liquisys oxygen

Product family: Liquisys chlorine, Liquisys conductivity, Liquisys oxygen, Liquisys pH/ORP

Product family: Liquisys chlorine, Liquisys conductivity, Liquisys oxygen, Liquisys pH/ORP

Product family: Liquisys oxygen

Product family: Liquiline, Liquiline M, Liquisys chlorine, Liquisys oxygen, Liquisys pH/ORP

Product family: Liquisys chlorine, Liquisys conductivity, LIQUISYS M, LIQUISYS OXYGEN, Liquisys turbidity, SmarTec S

Liquisys COM253

General Station Description (GSD) - Liquisys Oxygen - PROFIBUS PA

General Station Description (GSD) - Liquisys Oxygen - PROFIBUS DP

Device Type Manager (DTM) - Liquisys Oxygen - PROFIBUS PA

Device Type Manager (DTM) - Liquisys Oxygen - HART

Back

Kit CXM2X3 Relaismod. 2rel

KIT CXM2X3 relay mod. 2rel / CSA

Kit CXM2X3 Relaismodule 4rel

KIT CXM2X3 relay mod. 4rel / CSA

Kit CXM2X3 Relais Mod. 2rel.+I/CSA

Kit CXM2X3 Relais Mod. 4Rel+I/CSA

KIT COM2x3 Central module I1

KIT COM2x3 Central module I1 HART

KIT COM2x3 Central module I2

KIT COM2x3 central module I2 HART

KIT COM2X3 central module Profibus PA

Kit COM2X3 central module Profibus DP

Kit COM2x3: Central mod. PB DP; H/W 2.1x

Kit CxM2x3: Relay mod. for PBDP; H/W2.1x

KIT MKO1 Transmitter O2/Temperature

KIT MKO1 Transmitter O2/Temp./pressure

KIT MKO5 Transmitter O2/Temp./pressure

KIT CXM2X3 power supply 100..230 V AC

KIT CxM2x3 power supply 24 AC/DC

KIT CXM253 housing cover

Kit CxM253: Front foil + 6 key lifters

KIT COM253 sensor panel jack SXB

KIT CXM253 Internal housing parts

KIT CXM253 bottom of housing

KIT CXM/153/253: 2 pair of hinges

KIT CXM253 terminal strip power supply

KIT CXM253 Ribbon cables

Upgrade "Plus-Package" for LIQUISYS-M

Upgrade Kit from COS41 to COS31+COS61

Post mounting kit for LIQUISYS

Upgrade "Plus-Package" for COM 2X3

Upgrade cleaning for LIQUISYS-M

Dissolved oxygen transmitter
Liquisys COM253