EMS WatchDog Opacity/Dust Monitor
EMS WatchDog
The EMS WatchDog is a dual-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:
- Boilers
- Combustion Furnaces
- Crematoriums
- Process Industries
- Manufacturing Industries
- Electrostatic Precipitators
- Ductwork
- Bag Houses
- 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 | Dual-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 |
Dual-Pass Opacity Monitor Applications
The standard WatchDog is suited to boilers, combustion furnaces, crematoriums, process and manufacturing industries, electrostatic precipitators, ductwork, baghouses and cement kilns. Its 3–50 ft physical path capability is especially useful for wider stacks and ducts that exceed the range of many compact process monitors.
Frequently Asked Questions
Does the standard EMS WatchDog meet EPA PS-1?
Yes. The WatchDog data sheet states that its design and performance meet or exceed 40 CFR Part 60, Appendix B, Performance Specification 1 and ASTM D6216. The final installation, certification and ongoing quality-assurance program must also satisfy the facility’s applicable permit requirements.
How is the standard WatchDog different from the WatchDog PS-1 touchscreen model?
Both are dual-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.
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.
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.
