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Density calculator QML51 - vibronic-based measurement

Adaptable to diverse application environments through various sensor options

Density calculator QML51 - vibronic-based measurement

Adaptable to diverse application environments through various sensor options

This product is not available in this region.

Please contact your Endress+Hauser sales partner for any further questions.

Benefits

  • Real-time inline density data replaces manual sampling and laboratory analysis
  • Proven vibronic technology ensures repeatable measurement results with minimal sensitivity to build-up
  • Modular connectivity with industry-specific Liquiphant vibronic sensors and two additional input channels optionally used for temperature and pressure sensors
  • Fast and guided commissioning via integrated web server with selectable, predefined concentration tables
  • Verification of sensor accuracy provides precise and stable measurement results
FLEXible answers to individual needs
Current product

Density calculator QML51 - vibronic-based measurement

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  • High-end products
  • Highly functional and convenient

What is FLEX?

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

Learn more

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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24/7 customer portal

Personalized transaction space

Check prices and delivery times, save your favorite products, create quotes and place orders in just a few clicks and track deliveries at any time. With access to your complete order and quote history including all relevant documents you benefit from full transparency throughout the entire process.

Easy access to technical documentation

Select and download all technical documentation such as operating manuals, calibration certificates, approvals and CAD drawings conveniently bundled as a complete documentation package for your entire order or quote.

My Endress+Hauser – all in one place

My Endress+Hauser is your 24/7 connection to Endress+Hauser – in the office, in the field or on the go. It brings together transaction management, documentation and software downloads, knowledge base access, customer support, engineering tools and cloud‑based IIoT services helping you work easier, faster and more efficiently.

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Product information

Specifications
Point Level / Liquids
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Description

Density calculator QML51 enables continuous inline measurement of density, reference density and concentration of liquids as well as media detection using proven vibronic measurement technology. The calculator operates with up to two Liquiphant vibronic sensors with integrated density electronics and compensates for temperature and pressure influences by integrating dedicated sensors. Its modularity makes it ideal for liquid applications in tanks and pipelines across a wide range of industries.

Field of application

Thanks to industry-specific sensors, density calculator QML51 is suitable for diverse applications:

  • Chemical: Reliable measurement in aggressive media (e.g. concentration in batch reactor)
  • Mining, Minerals & Metals: Robust performance in abrasive media (e.g. lime milk concentration)
  • Food & Beverage: Accurate measurement in hygienic processes (e.g. media detection in soft drink production)
  • Life Sciences: Inline monitoring of media composition
Benefits
  • Real-time inline density data replaces manual sampling and laboratory analysis
  • Proven vibronic technology ensures repeatable measurement results with minimal sensitivity to build-up
  • Modular connectivity with industry-specific Liquiphant vibronic sensors and two additional input channels optionally used for temperature and pressure sensors
  • Fast and guided commissioning via integrated web server with selectable, predefined concentration tables
  • Verification of sensor accuracy provides precise and stable measurement results
Downloads
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Technical Information (TI)
TI Density Calculator QML51 Vibronic
English version - 07/2026
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Technical Information (TI)
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Technical Information (TI)
TI Liquiphant FTL51B Density with Density Calculator QML51 Vibronic
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All downloads
22 Downloads
Technical Information (TI)
Most downloaded
TI Density Calculator QML51 Vibronic
English version - 07/2026
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Technical Information (TI)
TI Liquiphant FTL63 Density with Density Calculator QML51 Vibronic
English version - 07/2026
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Technical Information (TI)
TI Liquiphant FTL51B Density with Density Calculator QML51 Vibronic
English version - 07/2026
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Technical Information (TI)
TI Liquiphant FTL62 Density with Density Calculator QML51 Vibronic
English version - 07/2026
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Operating Instruction (BA)
BA Liquiphant FTL63 Density with Density Calculator QML51 Vibronic
English version - 07/2026
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Operating Instruction (BA)
BA Density Calculator QML51 Vibronic
English version - 07/2026
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Operating Instruction (BA)
BA Liquiphant FTL62 Density with Density Calculator QML51 Vibronic
English version - 07/2026
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Operating Instruction (BA)
BA Liquiphant FTL51B Density with Density Calculator QML51 Vibronic
English version - 07/2026
Download
Short Instruction (KA)
KA Liquiphant FTL62 Density with Density Calculator QML51 Vibronic
English version - 07/2026
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Short Instruction (KA)
KA Liquiphant FTL63 Density with Density Calculator QML51 Vibronic
English version - 07/2026
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Short Instruction (KA)
KA Density Calculator QML51 Vibronic
English version - 07/2026
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Short Instruction (KA)
KA Liquiphant FTL51B Density with Density Calculator QML51 Vibronic
English version - 07/2026
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Installation Instructions (EA)
EA Terminal set Fieldgate NXA80
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Density Computer QML51
English version - 02/2026
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Special Documentation (SD)
SD Density Computer QML51 Modbus TCP server Quality
English version - 02/2026
Download
Special Documentation (SD)
SD DATEXEL DAT8024M Converter Modbus TCP to 4-20 mA Vibronic
English version - 03/2026
Download
Special Documentation (SD)
SD Density Computer QML51 OPC-UA server Vibronic
English version - 02/2026
Download
Innovation (IN)
Innovation Brochure - Density calculator QML51 For inline density measurement with vibronic technology
English version - 01/2026
Download
Innovation (IN)
密度演算器 QML51 音叉式測定技術によるインライン密度測定
Japanese version - 04/2026
Download
Innovation (IN)
Calcolatore di densità QML51 Calcolatore di densità QML51
Per la misura continua in linea
con tecnologia a vibrazione
Italian version - 04/2026
Download
EU Declaration
Product family: Density calculator Product root: QML51-
Declaration number: EU_01266_01.26
English version - 02/2026
Download
Miscellaneous
Product family: Density calculator Product root: QML51-
Region: Eurasian Economic Union
Approval agency: EAC
Approval number: TR CU 020/2011
Russian version - 04/2026
Download
Radio Equipment
Product family: Density calculator Product root: QML51-
Region: Australia
Approval agency: ACMA
English version - 03/2026
Download

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Spare parts and accessories

Terminal module
Terminal module

Terminal set NXA80 4-20 mA w/ HART,QML51

Terminal module
Terminal module
Order code 71727732
Drawing number 35
further parts
further parts

Signal converter Modbus TCP/4-20 mA

further parts
further parts
Order code 71765893

RN22 active barrier ATEX

Order code 71748585

RN22 active barrier CSA C/US

Order code 71748586
Spare parts and accessories