The M420 transmitter series stands for reliability in loop-powered applications. When your process requires the highest safety level for pH, oxygen and conductivity measurement, the M420 brings you the best performance and the advantages of the state-of-the-art ISM technology* for efficient maintenance.

Replaced with: Transmitter M400 2H

Reliable 2-Wire Transmitter

Reliable 2-Wire Transmitter.This M400 2-wire transmitter provides the highest reliability and process safety in hazardous and non-hazardous areas. Advanced ISM functionality enables predictive maintenance to help reduce costs and improve productivity.

Outstanding Reliability and Safety

The M400 2-wire provides outstanding reliability and process safety thanks to advanced ISM functionality and its rugged aluminum die cast housing.

Designed for Versatility

This transmitter accepts pH, ORP, Conductivity, DO, and dissolved CO2 sensors as well as both analog or digital ISM sensors, giving flexibility in use.

Easy System Integration

The HART interface allows easy system integration and offers remote access to the transmitter and sensor diagnostics

Specifications - M420 Transmitter Series

ISM	Plug and Measure™, DLI, ACT
Protection	IP 67
Approvals	CE, ATEX / IECEx / FM/CSA, Zone 1 / Cl I Div 1 (pending)
Temperature range	- 20 °C to 65 °C (- 4 °F to 149 °F)
Digital Input/Output	optional: HOLD and CONTROL
User Interface	LC display, 7 segment with icons, backlit (white)
Current Output	2nd passive current output optional
Service Interface	IrDA
Communication	HART
Short description	for pH, O2, conductivity
Parameters	pH/ORP, DO, O2 gas, conductivity
Communication	HART®
Hazardous Area Classification	ATEX, IECEx, CSA, FM
Sensor Type	Analog or ISM

Features and Benefits

Reliability by design

The M420 transmitter development was focused on rugged design and resistance to the most difficult operation conditions. This allows the M420 to stand out for its superior operational reliability in chemical, pharmaceutical or gas phase oxygen applications.

Versatility thanks to mixed-mode input

Available for a whole range of measurement parameters, the M420 is compatible with both conventional and ISM sensors.

Additional functionality for greater flexibility

Configure your M420 to better suit your process needs. Add a second analog output or select the extended logbook, 21 CFR Part 11 conformity with AuditTrail™ or trace oxygen measurement. Use the HART communication ability of the M420 transmitter series for your application.

One step ahead of maintenance

Stay ahead of your maintenance tasks with the ground-breaking Intelligent Sensor Management (ISM) Technology from METTLER TOLEDO. ISM-equipped measurement loops are efficient to maintain without compromising on your process reliability.

Predictive maintenance thanks to ISM technology

Thanks to the ACT (Adaptive Calibration Timer), calibration intervals for each measurement loop can be flexibilized, based on the real-time sensor information and current process conditions.

* for pH and O2 sensors

Case Studies

Process Analytics

pH/ORP (Redox) Probes, Oxygen, CO₂, Ozone Sensors, Bioburden, Total Organic Carbon, Gas, Sodium, Silica and Chloride/Sulfate Analyzers, Transmitters

Applications

Process Analytics

pH/ORP (Redox) Probes, Oxygen, CO₂, Ozone Sensors, Bioburden, Total Organic Carbon, Gas, Sodium, Silica and Chloride/Sulfate Analyzers, Transmitters

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M420 Transmitter Series - Discontinued Product

For hazardous area applications

Replaced with: Transmitter M400 2H

Reliable 2-Wire Transmitter

Reliable 2-Wire Transmitter.This M400 2-wire transmitter provides the highest reliability and process safety in hazardous and non-hazardous areas. Advanced ISM functionality enables predictive maintenance to help reduce costs and improve productivity.