Opacity Monitor Learning Center
Industrial Opacity Monitoring Resources
Practical resources for understanding, selecting and maintaining industrial opacity monitors. Explore measurement fundamentals, compare single-pass and double-pass systems, review EPA PS-1 information, and find EMS manuals, forms and technical resources.
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Featured Opacity Monitor Guides
Start with the fundamentals, compare the available optical arrangements and then use the selection guide to match a monitor to your permit, process and installation.
How Opacity Monitors Work
See how a light source, measurement path, detector and controller produce a continuous opacity reading—and why zero, span, alignment and clean optics matter.
Single-Pass vs. Double-Pass
Compare the two optical arrangements, understand how light travels through each system and learn which application and compliance questions should guide selection.
Choose the Right Opacity Monitor
Use permit requirements, optical path, process conditions, outputs, alarms, calibration and service needs to identify the appropriate type of monitor.
Compare Opacity Monitoring Systems
Industrial Opacity and Dust Monitors
Compare the WatchDog, WatchDog 800, WatchDog PS-1 and Guardian by optical arrangement, application, path length, outputs and compliance capabilities.
EPA PS-1 Continuous Opacity Monitoring
Review EMS systems for applications requiring U.S. EPA 40 CFR Part 60, Appendix B, Performance Specification 1.
Review EMS EPA PS-1 opacity monitoring systems
Read the official EPA Performance Specification 1
Application-Specific Opacity Monitoring Guides
Opacity-monitoring needs vary by process, permit and purpose. This section will expand as EMS publishes guidance for specific industries, equipment and operating conditions.
Crematory and Incinerator Smoke Monitoring
Review selectable alarm settings, optical-path requirements and installation considerations for smoke-opacity detection on cremation equipment and industrial incinerators.
Explore crematory and incinerator smoke monitoring
- Boilers and power generation
- Cement and aggregate processing
- Paper mills
- Baghouses and ESPs
- Duct and exhaust monitoring
- Process-control applications
Documents, Service and Technical Resources
Manuals, Data Sheets and Forms
Find current EMS manuals, data sheets, brochures, dimension sheets and service forms.
Service, Audits and Certification
Review startup, certification, quarterly-audit, field-service and factory-service support for EMS opacity monitors.
Neutral-Density Filter Certification
Find audit-filter certification information and support for periodic opacity-monitor quality-assurance checks.
Rosemount OPM Support
Learn about EMS replacement parts, repair service and direct replacements for Rosemount OPM 3000, OPM 4000 and OPM 4001 opacity monitors.
Need Help Selecting an Opacity Monitor?
Send EMS your permit language, process description, stack or duct dimensions, temperature range, mounting details and required outputs. We can help identify the appropriate monitoring system and supporting services for your application.
Request an opacity monitor quote
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Monitoring requirements depend on the facility permit and applicable federal, state and local rules. Confirm regulatory requirements with the appropriate permitting authority.