Why Do I Need a Continuous Opacity Monitor?
Opacity Monitor Learning Center
A continuous opacity monitor gives operators an ongoing view of how much light is blocked by smoke or other particulate in a stack or duct. It can help you identify changes in a process, connect opacity readings to compatible controls, and maintain the monitoring records your application requires.
Start with the job you need the monitor to do
The first question is whether you need a smoke alarm, a continuous measurement for process control, or a monitoring system that meets a specific compliance requirement. These are different needs. Choose the equipment, outputs and documentation around the purpose of the installation.
See changing process conditions
A continuous reading can show changes that a simple threshold alarm does not describe. Operators can compare readings with startup, changes in loading, maintenance or other operating events. When connected to compatible recording equipment, opacity measurements can help a team investigate recurring changes and compare conditions before and after corrective work.
An increased reading is a reason to investigate, not a diagnosis by itself. Check the process along with instrument alignment, optical cleanliness and operating status before deciding what action to take.
Crematory smoke and opacity monitoring
A crematory opacity monitor can give equipment manufacturers and end users measurement information for crematory smoke monitoring. Consider whether the installation needs a continuous opacity value, a recording signal, an alarm output, or a combination of these functions.
The EMS WatchDog 800 single-pass continuous opacity monitor supports crematorium process-monitoring applications, with a 4–20 mA output and alarm relay. Confirm the optical path length, mounting arrangement, control-system compatibility and facility requirements before selecting equipment.
Choosing a boiler opacity monitor
A boiler opacity monitor can provide ongoing information about visible particulate in the measurement path. For process monitoring, consider the WatchDog 800. For a project requiring documented PS-1 performance, discuss the EMS WatchDog and WatchDog PS-1 continuous opacity monitoring systems with EMS.
Selection also depends on stack dimensions, environmental conditions, access for maintenance and the required signals. Review the industrial opacity monitor selection guide before specifying a model.
Determine whether compliance monitoring is required
Continuous measurement alone does not establish regulatory compliance. A facility’s applicable rules and air permit determine its monitoring obligations. PS-1 describes performance and installation requirements for covered continuous opacity monitoring systems; it does not mean that every boiler or crematory must install one. Confirm applicability with the permitting authority. See the EPA PS-1 reference.
Plan for service as well as installation
Budget for access, cleaning, alignment checks, calibration and any required audits. If an existing monitor is unreliable, provide its model, symptoms and service history before deciding whether to repair or replace it. EMS provides opacity monitor repair and service, including factory and field support.
What should I send EMS?
- Your application, equipment manufacturer and site location.
- Stack or duct dimensions, mounting details and photographs.
- Whether you need measurement, alarms, recording or compliance reporting.
- Required control signals and any existing monitor model.
- The relevant monitoring requirements from your permit or project specification.
Request help selecting continuous opacity monitoring equipment or call EMS at 800-864-2814.
New to the technology? Read What Is a Continuous Opacity Monitor?