WatchDog 800
The EMS WatchDog 800 is a compact, green-LED, single-pass opacity monitor designed to provide accurate, affordable and reliable process-control information. This industrial opacity monitor supports optical path lengths from 3 to 8 feet (91–244 centimeters).
The electronically modulated green LED provides continuous, low-maintenance opacity measurement for industrial applications. As a single-pass opacity monitor, the WatchDog 800 is designed for straightforward installation in applications such as:
- Crematoriums
- Boilers
- Bag Houses
- Duct Systems
- Fan Control
The EMS WatchDog 800 is well suited to Title V opacity monitoring, oven and diesel exhaust, duct fire-alarm applications, multi-point systems and other particulate-monitoring processes. Confirm the monitoring and reporting requirements in your facility’s permit when selecting an instrument.
Since 1990, companies worldwide have relied on EMS to monitor visible emissions, smoke, dust and opacity from industrial processes.
WatchDog 800 Opacity Monitor Specifications
| Measurement method | Single-pass opacity measurement |
|---|---|
| Light source | Electronically modulated green LED |
| Opacity range | -100% to 100% |
| Resolution | 1% opacity |
| Optical path length | 3–8 ft (91–244 cm) |
| Analog output | One 4–20 mA output |
| Alarm output | 2 A alarm relay |
| Controller enclosure | NEMA 4X, approximately 10 H × 6 W × 5 D in |
| Power | 24 VDC supply; 90–240 VAC power-supply input |
| Operating temperature | 0–52°C |
| Approvals | CE, UL and cUL |
Continuous Single-Pass Opacity Monitoring
The WatchDog 800 is a continuous opacity monitor that measures the reduction in light transmitted across the process opening. Its green LED sends light from the emitter to the detector in one pass. The opacity signal helps operators follow changes in visible emissions and connect monitoring information to compatible plant controls.
When comparing continuous opacity monitoring equipment, consider the measurement path, mounting access, required outputs and purpose of the measurement. Read our guide to single-pass versus double-pass opacity monitors or learn how opacity monitors work.
WatchDog 800 Industrial Applications
Crematory Opacity and Smoke Monitoring
For manufacturers and operators evaluating a crematory opacity monitor, the WatchDog 800 provides continuous measurement and alarm information for process monitoring. Crematory smoke monitoring helps operators recognize changes in visible exhaust and investigate operating conditions. Its 4–20 mA output and alarm relay support integration with compatible cremation equipment controls.
To select a crematory smoke monitor, confirm the stack or duct dimensions, optical path length, mounting arrangement and control-system requirements. EMS can help assess new installations and replacement monitors for cremation and incinerator equipment. Suitability depends on the installation and the facility’s monitoring requirements.
Commercial Boiler Opacity Monitoring
A commercial boiler opacity monitor gives operators a continuous indication of changes in visible particulate emissions in the exhaust. The WatchDog 800 provides process-monitoring and alarm information where its single-pass design, 3–8 ft optical path and available outputs match the installation.
When discussing a boiler application with EMS, include the fuel, stack or duct dimensions, operating conditions and any permit requirements. These details help determine whether the WatchDog 800 or another EMS model is the appropriate choice.
Baghouses, Duct Systems and Industrial Exhaust
The WatchDog 800 also supports process-monitoring applications involving baghouses, duct systems, fan controls, oven exhaust and diesel exhaust. Changes in the opacity signal can prompt an operator to investigate a change in the process or dust-collection system. Review the installation and measurement requirements with EMS before selecting a configuration.
Installation, Maintenance and Service
Plan for suitable mounting locations, optical alignment and access for inspection and cleaning. Follow the WatchDog 800 manual for the installation and maintenance procedures applicable to your system. Cleaning and inspection frequency should reflect operating conditions and contamination at the installation.
EMS has manufactured and serviced opacity monitors since 1990. For troubleshooting, replacement parts or repair, review our opacity monitor service and support options. Find current manuals on the Documents & Forms page.
Frequently Asked Questions
Is the WatchDog 800 a single-pass or double-pass opacity monitor?
It is a single-pass monitor. The green LED travels once across the process opening from the emitter to the detector.
What optical path lengths does it support?
The WatchDog 800 is designed for path lengths from 3 to 8 feet (91–244 cm). Share your stack or duct dimensions with EMS to confirm the installation requirements.
What outputs are available?
The system provides one 4–20 mA analog output and a 2 A alarm relay for connection to compatible process controls and recording equipment.
Can the WatchDog 800 be used as a crematory smoke monitor?
Yes, crematory process monitoring is one of its applications. EMS can help confirm that the optical path, mounting arrangement, outputs and monitoring requirements fit your cremation or incineration equipment.
When should I choose the WatchDog 800 instead of the PS-1?
Choose the WatchDog 800 when single-pass process opacity monitoring fits your application. Continuous measurement alone does not establish that an instrument meets a particular compliance requirement. Facilities that specifically require a 40 CFR 60 Appendix B, Performance Specification 1 system should review the EMS WatchDog PS-1 and our EPA PS-1 opacity monitoring guide.
What information should I include when requesting a quote?
Include the application, stack or duct dimensions, required outputs, installation location and relevant permit requirements. For a replacement, include the existing monitor model and photos if available. Our industrial opacity monitor selection guide explains the main factors to consider.
Compare the EMS Guardian and WatchDog 800 to review smoke detection, continuous opacity monitoring, alarms, outputs and application needs.
WatchDog 800 Documents and Support
Download the WatchDog 800 data sheet, find the installation manual in Documents & Forms, or compare EMS industrial opacity monitors.
Request a WatchDog 800 Quote
Planning a crematory, commercial boiler or industrial exhaust application? Request a WatchDog 800 quote and tell us about your installation. EMS can help you select an appropriate monitoring system and the support you need.
Contact us for more information or a customized quote for the EMS WatchDog 800.
