Michell Instruments have developed a new EExd certified process moisture analyser, the world's first, as a result of extensive end user contact and experience
As specialists in dew point measurement for industrial, process and research applications, Michell Instruments has over 25 years of experience in satisfying the moisture measurement needs of the hydrocarbon and petrochemical industries. As a result of such extensive end user contact and experience, combined with expertise in the industry, Michell Instruments have developed a new EExd certified process moisture analyser. Promet EExd meets all the requirements of the customer looking for a complete and total hazardous area installed solution.

Promet EExd is the latest addition to the comprehensive Michell Process Instrumentation range which includes further analysers for hydrocarbon dew point in natural gas and process moisture measurement in petrochemical liquids.

Promet EExd is the world's first purpose designed EExd flameproof certified process moisture analyser.

Based on Michell Instruments experience in this critical and often arduous field of measurement, Promet EExd is a radical new concept where the highest priorities have been given to the demands of the customer in terms of simplicity of installation, total plant communications integration, moderate cost of ownership, and highest calibration integrity.

Promet EExd offers the customer a complete moisture measurement package for critical gas applications with features including EExd Flameproof ATEX and CSA certification, complete zone 1 or 2 installation and a remote interface option for mounting in a safe area location if required.

The new process moisture analyser also offers single and dual-channel moisture content capability, with integrated electronic pressure measurement, within the same single field installed flameproof housing.

Promet EExd is the second introduction to the new Michell EExd Process Instrumentation Range all of which feature complete hazardous area installation in classified zones 1 or 2.

This latest addition follows on from the highly successful Condumax II Hydrocarbon Dew-Point Analyser for Natural Gas applications.

In addition to the simplicity of installation, Promet EExd offers the perfect solution for those large petrochemical process plants, such as refineries and LNG liquefaction plants, which state a strong preference that all instrumentation be certified flameproof.

The new Process Analyser is ATEX certified to: Group II, Category 2 G Code: EEx d IIB + H2 T4 Tamb -40 +60C IP66.

Promet EExd is also awaiting CSA certification to Div 1, Class 1, Group B, C , D.

The Process Moisture Analyser also provides customers with the option of a remote interface, which acts as a dedicated host within a control or instrument room, providing advanced graphical display of measurement and status information, data logging and access to programme configuration functions for up to 31 analysers.

Each analyser communicates with the remote interface through the Modbus RTU, so transferring all of the functionality of the main unit through into the comfort and convenience of an indoor safe area environment.

Global access to all functionality is provided through any web browser directly into the embedded website of the remote interface itself, so facilitating the needs of users with unmanned sites and enabling Michell to provide export support services without the need for a site engineer visit.

Promet EExd utilises the advanced Michell Ceramic Moisture Sensor technology, of which 1,000 are in operation today in natural gas and petrochemical industries.

The Ceramic Sensor technology is manufactured from inert materials that are inherently resilient to aggressive chemicals, achieving class leading accuracy and long-term stability.

The robust sensor design withstands 300 barg without any risk of failure due to pressure shock, unlike traditional aluminium-oxide sensors that commonly suffer premature failure on rapid increase or decrease in pressure at start-up or shut-down.

Each individual sensor is calibrated traceable to NPL (UK) and NIST (USA) through the Michell world-class calibration facilities which are recognised through the UKAS accreditation.

Accuracy of measurement is +/-10 % of reading to single figure ppbV levels and +/-20 % of reading at lower moisture contents into the ppmV regions.

A unique service offered by Michell enables users to maintain such high precision for the Process Moisture Analyser in continuous, virtually uninterrupted operation through the Michell Calibration Exchange Service.

The Exchange Service provides a freshly certified sensor to the customer site for interchange with the existing sensor in operation.

This is a process that takes only minutes to perform without any requirements for programming or data entry.

Each individual sensor has its unique calibration characteristics programmed into on-board, non-volatile memory, which is instantly accessed on power-up of the Process Moisture Analyser.

The Michell Calibration Exchange also provides the user with highest level of calibration integrity for Promet EExd and at a cost that is often less than traditional return-to-manufacturer re-calibration service, but without any of the associated costs of analyser downtime and spares stock holding.

Promet EExd offers good sampling system design, applying best practice specific to the application and installation concerned.

Such attention to detail is critical to the performance of any on-line process analyser.

This is particularly true for moisture measurement whereby, in order to sense the change in concentration of moisture molecules, the active area of the sensor itself must be in direct contact with the gas to be measured.

The sensor is therefore potentially exposed to any sample borne contamination, so effective sample filtration is most critical, or aggressive chemicals present in the gas composition, whereby the attributes of the Michell Ceramic Sensor come to the fore.

The Michell Promet EExd Premium Sampling Systems are available in three installation configurations.

These comprise of an open panel version for indoor installation in a field analyser house, or a choice of GRP or 316 enclosures both offering IP66/NEMA 4 ingress protection for installation in the field adjacent to the pipeline or process plant to enable a fully hazardous area installation of the whole moisture analyser.

The Premium Sampling System range are available in two standard core designs to provide solutions to key applications: in answer to the needs of natural gas producers and distribution companies the Natural Gas Process and Pipeline Transmission Sampling System incorporates the latest micro-porous membrane filtration to provide 100 % protection against all liquid contaminants whilst an in-line adsorption cartridge removes even vapour phase glycol contamination.

For the petrochemical refinery, the Trace Moisture Measurement in Hydrocarbon Gas Sampling System takes a minimalist design approach to ensure that the Ceramic Sensor responds dynamically to the low trace moisture levels, often at sub-parts per million levels, that are essential to many refinery gas processes.

A key application for the Promet EExd with this sampling system is molecular sieve dehydration processing of natural gas prior to cryogenic liquefaction to produce LNG, at dewpoint levels in the region of -90Cdp.

This is evident where any significant moisture present, above a small faction of ppmV, would result in unacceptable ice formation within the process and potential plant blockage, with severe repercussions to productivity.

An extensive list of options is available for both of the core sampling system designs to accommodate needs for higher-pressure ratings up to 138barg/2,000 psig and enclosure heating/cooling options to suit even the most extreme climate.

A further option is trace heated/insulated sample tubing which has been made available for the first time as a convenient and cost effective factory fitted item for customers to specify at time of order.

The trace heated sample line avoids any potential for condensation in the sample gas due to cold temperature conditions, which would otherwise jeopardise the integrity of the measurement.

Where either of the two core sampling systems is not suitable, Michell Instruments provide custom designed sampling system solutions specific to user application/installation requirements.