EMS WatchDog Opacity/Dust Monitor
EMS WatchDog
The EMS WatchDog is a double pass opacity and dust monitor designed for continuous measurement across industrial stacks and ducts. Light travels from the transceiver to a reflector and back, providing a rugged optical system for monitoring visible emissions, process conditions and filtration performance.
The system meets or exceeds U.S. EPA 40 CFR Part 60, Appendix B, Performance Specification 1 and ASTM D6216. It supports physical path lengths from 3 to 50 feet and combines NEMA 4 optical hardware, an LED light source with automatic aging compensation, through-the-lens alignment and a panel-mounted controller.
The controller can display opacity, optical density and configured dust-concentration values while providing analog, relay and MODBUS communication options for compatible plant systems.
Typical applications include:
- Commercial Boilers
- Heat Exchangers
- Combustion Furnaces
- Crematoriums and Incinerators
- Process Industries
- Manufacturing Industries
- Electrostatic Precipitators
- Commercial Duct Systems
- Dust Collectors and Baghouses
- Cement Kilns
The EMS WatchDog combines a wide physical path range with multiple controller outputs, making it suitable for many industrial opacity and dust-monitoring installations. Since 1990, companies worldwide have relied on EMS equipment and service to monitor visible emissions from their processes.
EMS WatchDog Specifications
| Optical system | Double pass LED with Type 1 reflector |
|---|---|
| Compliance | Meets or exceeds 40 CFR Part 60, Appendix B, PS-1 and ASTM D6216 |
| Physical path length | 3–50 ft |
| Measurement ranges | -5% to 100% opacity; 0–2 optical density; configurable dust-concentration display |
| Display resolution | 0.1% opacity; 0.001 optical density |
| Accuracy | ±1% of full scale |
| Response time | Less than 10 seconds to 80% of full scale |
| Controller display | 2.4-inch monochrome display with LED backlight and selectable process screens |
| Analog outputs | Two 4–20 mA outputs, individually configurable |
| Relay outputs | Six relays with field-programmable alarm set points |
| Network | MODBUS protocol over RS-485 |
| Calibration | Push-button clear-path zero/span; manual or automatic gain, LED, zero, span and linearity calibration |
| Optical enclosures | NEMA 4 watertight transceiver and reflector hardware |
| Controller enclosure | IP65/NEMA 4X when panel mounted |
| Ambient temperature | 0–130°F (-17–54°C) |
| Process-gas temperature | Up to 750°F (400°C) at the measurement location |
| Light-source life | 62,000 hours or more; field replaceable with automatic aging compensation |
| Power | 24 VDC; EMS supply accepts 90–240 VAC, 50/60 Hz |
| Approvals | CE, UL and cUL |
WatchDog Continuous Opacity Monitor Applications
The EMS WatchDog provides continuous opacity and dust monitoring across commercial and industrial stacks and ducts. Its double pass optical design and 3–50 ft physical path range support applications where operators need visibility into exhaust conditions and filtration performance.
Commercial Boilers and Heat Exchangers
The WatchDog can monitor opacity in exhaust streams serving commercial boilers and heat exchangers. Continuous measurement helps operators track changes in visible emissions during operation. For a commercial boiler opacity monitor or heat-exchanger application, EMS can review the exhaust arrangement, measurement location and plant-control requirements.
Commercial Duct Systems, Dust Collectors and Baghouses
Applications include commercial duct systems, dust collectors, baghouses and electrostatic precipitators. The WatchDog monitors changes in opacity and dust in the exhaust stream to help operators assess filtration performance and investigate changing process conditions. Share the duct dimensions and proposed monitoring location so EMS can help select the configuration.
Crematoriums, Incinerators and Industrial Processes
The WatchDog is used for opacity monitoring in crematorium and incinerator exhaust applications, as well as combustion furnaces, cement kilns, process industries and manufacturing operations. EMS can review the stack or duct arrangement and operating conditions to determine the appropriate monitoring setup.
For application review, provide the stack or duct width, exhaust temperature, process description and required outputs. Equipment selection, installation and any certification or audit requirements depend on the facility and its applicable permit requirements.
Request a WatchDog quote for your application or explore opacity monitor audits, maintenance and repair.
Frequently Asked Questions
How is the standard WatchDog different from the WatchDog PS-1 touchscreen model?
Both are double pass systems designed for PS-1 applications. The standard WatchDog uses a traditional 2.4-inch panel controller and supports physical paths from 3 to 50 feet. The WatchDog PS-1 uses a 5.7-inch color touchscreen with expanded trends and diagnostics. The WatchDog PS-1 also performs automatic daily calibration checks and provides additional relays and outputs compared with the standard WatchDog.
Can the WatchDog communicate with plant controls?
Yes. It provides two individually configurable 4–20 mA outputs, six programmable relay contacts and MODBUS communication over RS-485.
Can the WatchDog display dust concentration?
The controller supports configurable dust-concentration display ranges in addition to opacity and optical density. A site-specific relationship between optical measurement and particulate concentration may be required for meaningful mass-concentration reporting.
Compare the standard EMS WatchDog and WatchDog PS-1 to review controllers, calibration features, relays, outputs and application requirements.
WatchDog Documents and Support
Download the EMS WatchDog data sheet. Learn how opacity monitors work, compare single-pass and double-pass systems, or review how to choose an industrial opacity monitor. For startup, certification, quarterly audits or repairs, visit Service and Documents or contact EMS.
