Mettler Toledo M800 Multi-Channel Process Transmitter

Overview

Mettler Toledo M800 is a full-colour, multi-channel, multi-parameter transmitter for process monitoring. It is offered in one-, two- and four-channel versions that monitor one, two or four in-line sensors at the same time, with additional inputs for flow sensors on the water versions. The M800 integrates with Intelligent Sensor Management, known as ISM, so that digital sensors pass calibration data and diagnostic information to the transmitter and help the user plan maintenance instead of reacting to failures.

Operators of water, power and process plants in Oman and the GCC often need to watch several liquid parameters at one point, for example conductivity, dissolved oxygen and pH around a boiler feed system, a reverse osmosis train or a cooling circuit. One Mettler Toledo M800 can replace several single-channel analyzers and put the readings, alarms and 4 to 20 mA outputs in a single enclosure. It sits comfortably alongside the liquid analysis instruments already listed by Seven Star LLC, such as the Endress+Hauser Liquiline CM442 multiparameter transmitter, the Liquiline M CM42 multichannel transmitter and the Hach LXV416 LDO2 dissolved oxygen sensor. Seven Star LLC supplies the Mettler Toledo M800 with engineering support in Muscat.

Measurement Principle

The Mettler Toledo M800 does not measure one quantity itself. It is a transmitter that powers, reads and evaluates the sensor connected to each channel, so its measuring principle is the principle of the sensor. With a glass pH electrode it evaluates a potential, with a conductivity cell it evaluates the electrical resistance or conductance of the liquid, with an amperometric oxygen sensor it measures a current in nanoamperes that is proportional to oxygen partial pressure, and with an optical sensor it evaluates a light signal from a luminescent layer. The same enclosure can therefore serve very different measuring tasks by changing the sensor and the parameter configuration.

The Mettler Toledo M800 operation manual lists the parameters that the instrument is designed to measure: conductivity, dissolved oxygen, oxygen in gas, dissolved ozone, dissolved carbon dioxide, pH and ORP, flow and turbidity. The version, indicated by the part number on the label, determines which parameters can be covered. Water versions add dissolved ozone and TOC sensors, while process versions add pH with pNa, dissolved carbon dioxide and thermal-conductivity CO2 sensors. Each channel evaluates temperature as well, and automatic temperature compensation is applied where the sensor requires it.

Engineering Design of the Mettler Toledo M800

The Mettler Toledo M800 is housed in a polycarbonate enclosure of 150 by 158 by 170 mm that weighs 1.6 kg and carries an IP66 rating when the back cover is attached. It is available in a half-DIN case size, and its integral IP66 housing allows wall or pipe mounting. The front carries a 5.7 inch colour touchscreen with a resolution of 320 by 240 pixels and 256 colours, and the main menu, trend display and sensor diagnostics are reached from it.

Electrically, the Mettler Toledo M800 accepts 100 to 240 V AC or 20 to 30 V DC at 10 W. It provides eight galvanically isolated 0/4 to 20 mA outputs, one 4 to 20 mA input, six digital inputs on the four-channel unit, a USB type B port, and eight relays, namely four mechanical SPST relays rated 250 V AC at 3 A and four reed relays rated 250 V at 0.5 A. Two PID controllers with pulse-length, pulse-frequency or analog control let the transmitter close a loop for dosing or aeration directly. ISM sensors can be connected at up to 80 m, optical oxygen sensors at up to 50 m, and the manual states a Class I Division 2 approval for the two- and four-channel versions.

Key Features

The following features explain why the Mettler Toledo M800 is widely specified for liquid analytics:

• One-, two- and four-channel Mettler Toledo M800 versions in a common design, so that one transmitter can monitor several sensors simultaneously.
• ISM digital sensor integration with plug-and-measure recognition and diagnostics that support predictive maintenance.
• 5.7 inch colour touchscreen with a graphical trend display and a menu structure protected by a security password.
• Eight galvanically isolated 0/4 to 20 mA outputs with linear, bi-linear, logarithmic or autoranging configuration.
• Four mechanical and four reed relays with adjustable alarm delay from 0 to 999 seconds.
• Two PID process controllers for pulse-length, pulse-frequency or analog control of dosing and aeration.
• Support for pH and ORP, conductivity, amperometric and optical oxygen, dissolved ozone, dissolved carbon dioxide, turbidity and flow sensors.
• Rugged polycarbonate enclosure with IP66 protection and a wide ambient range of minus 20 to 50 degrees Celsius.

Industrial Applications

Within power generation and desalination in Oman, the Mettler Toledo M800 is used to supervise boiler feed water, condensate polishing, reverse osmosis permeate and cooling-water treatment. A single four-channel unit can follow cation conductivity, dissolved oxygen and pH at one sampling panel and hand the data to the control system over the 4 to 20 mA outputs. In oil, gas and petrochemical plants at Sohar, Duqm and Salalah, the Mettler Toledo M800 process versions are suited to dissolved oxygen in injection water, conductivity in chemical process lines and pH control in effluent treatment.

Food, beverage and pharmaceutical facilities in Muscat use the same transmitter for fermentation, CIP monitoring and purified water loops, because the ISM diagnostics and the calibration records help demonstrate that the measurement is under control. Seven Star LLC supplies the Mettler Toledo M800 with the sensors, cables and mounting kits that a measuring point needs, and our engineers can check the version and part number against your sensor list before an order is placed.

Technical Specifications

The table summarises specification data for the Mettler Toledo M800 published in the Mettler Toledo operation manual. Sensor specifications are listed in the manuals of the ISM sensors.

How to Order

To request a formal quotation for the Mettler Toledo M800, send us the number of channels, the parameters and the sensor models you plan to connect, and tell us whether you need panel, wall or pipe mounting. Seven Star LLC supplies Mettler Toledo process analytical equipment to customers in Oman and the GCC, with engineering support from our instrumentation division in Muscat, and the technical documentation attached to this page.