The ML®675 or 675 ®Open Architecture (OA) is a pre-engineered Continuous Emissions Monitoring System (CEMS) designed for use in EPA 40 CFR Part 60 and Part 75 compliance applications and for process control. This dilution based system can be configured to accurately measure SO2, NOx, CO, CO2, and /or O2 on a wet basis.​​

Both configurations of the ML®675 CE​MS consist of a heated probe, heated sample umbilical, single bay cabinet, analyzers, control equipment, and a dilution air cleanup package. The Open Architecture version has the dilution air cleanup package mounted on a wall instead of the cabinet.

Using dilution extractive principles, pressurized dilution-air is used as the motive force to provide suction that mixes a small amount of stack gas into the same dilution air stream. This creates a diluted sample which returns under positive pressure to the analyzers for analysis. A precision mass flow meter is used to determine an accurate, real time dilution ratio. Since no moisture is actually removed from the original sample, measurements are made on a wet basis.

​​A programmable logic controller (PLC) performs all automatic sequencing of the sample cycle, daily calibration cycle, and back purge cycle. During calibration mode, zero and span gases are injected into the probe head to comply with EPA calibration requirements. Back purge air is delivered to the probe on a periodic basis to clean the heated probe filter, providing months of continued operation without maintenance.

​​In addition, the PLC has the ability to log fuel flows and provide the required analog outputs in units of diluent corrected ppm concentration (ppmc), lb/mmBtu, and lb/hour. Standard relay outputs that signal system status and fault information are also generated from the PLC. A RegPerfect® Data Acquisition System (DAS) may be attached to the PLC via Ethernet to provide long term data collection, compliance report generation, remote control and diagnostic information.

The ML®675 is a self-contained system requiring single point attachment for power, instrument air, and calibration gases. All utility distributions are routed through the ML®675 internally. No duplication of utilities is required on the stack.​​​

​​The following table provides a list of items that need regular maintenance to ensure your product remains in good working condition. See manual section 6 for detailed instructions and appendix A for checklists.

Maintenance