EMS WatchDog vs. WatchDog PS-1: Which Opacity Monitor Is Right for Your Application?

The standard EMS WatchDog and WatchDog PS-1 are double pass opacity and dust monitors designed for continuous monitoring in industrial stacks and ducts. The main differences are the controller, operating features, calibration functions and output capabilities.

Both systems are backed by Environmental Monitor Service, a certified veteran-owned small business manufacturing and servicing opacity monitors since 1990.

Compare the Features

Feature	Standard EMS WatchDog	EMS WatchDog PS-1
Measurement design	Double pass opacity and dust monitoring	Double pass opacity and dust monitoring
Controller	Traditional panel controller with a 2.4-inch monochrome display	5.7-inch color touchscreen
Operator information	Selectable process screens displaying opacity, optical density and configured dust-concentration values	Expanded trends and diagnostics, with five numeric screens and three trend displays
Calibration features	Push-button clear-path zero/span and manual instrument calibration functions	PS-1 required automatic daily calibration checks, selectable auto-cal frequency and manually initiated checks
Relays	6 relays	6 relays for alarms, field-programmable
Outputs	Two configurable 4–20 mA outputs and MODBUS over RS-485	Four 4–20 mA outputs, individually customer-selected full-scale ranges and modes
Regulations and standards	Meets or exceeds ASTM D6216	Meets or exceeds U.S. EPA 40 CFR Part 60, Appendix B, Performance Specification 1 (PS-1) and ASTM D6216

When Should You Consider the Standard WatchDog?

Consider the standard EMS WatchDog when you need an industrial double pass opacity monitor with a traditional panel controller for an application that does not require compliance with U.S. EPA Performance Specification 1 (PS-1).

Applications include:

• Commercial boilers and heat exchangers
• Commercial duct systems
• Dust collectors and baghouses
• Crematoriums and incinerators
• Industrial furnaces and manufacturing processes

The standard WatchDog provides continuous measurement for operators monitoring exhaust conditions, visible emissions and filtration performance. EMS can review your installation and monitoring requirements to determine whether it is the appropriate system.

View the Standard EMS WatchDog

When Should You Consider the WatchDog PS-1?

Consider the WatchDog PS-1 when your application requires PS-1 monitoring capabilities, automatic daily calibration checks, or the operating flexibility of a color touchscreen with expanded trends and diagnostics.

Its four individually configurable 4–20 mA outputs and six field-programmable alarm relays support integration with plant monitoring and control systems.

Applications include:

• Power plants, including facilities burning oil or coal
• Large commercial boilers and airport steam plants
• Foundry furnaces, cement kilns and industrial ovens
• Food manufacturing, including deep-fat frying and potato-chip production
• Multi-chamber crematory and incinerator installations sharing a common smokestack

Equipment selection and any certification or audit requirements depend on the installation and applicable permit requirements.

View the EMS WatchDog PS-1

Support Throughout the Life of Your Monitor

EMS provides startup assistance, certification, quarterly audits, preventive maintenance, factory repair and field service. Our team can help with equipment selection, installation planning and ongoing support.

Explore Opacity Monitor Service and Support