Standard Opacity & Dust Monitors

EMS has taken the approach to design our products with accuracy, reliability, and serviceability in mind. Our opacity monitors are designed to fit any application and budget. We offer both single and dual-beam measurement options as well as path-length measurement from 24 inches up to 50 feet. The high-quality optics and electronically-modulated light source assures accuracy and dependability.

Our industry-leading warranty and support make EMS opacity monitors an ideal choice for all of your opacity-monitoring needs. Customers worldwide have relied on Environmental Monitoring Service opacity monitors for more than 20 years.

EMS500 System

EMS WatchDog

  • Designed with ASTM D 6216 & PS-1 Grade Optics
  • Dual-Beam Measurement
  • Path Length of up to 50 Feet (15.24 Meters)
  • 8-Year Lamp Life Warranty
  • Measurement of -5-99% Opacity
  • Manual On-Line Calibration
  • Communications via RS485 MODBUS and 4-20ma


Control box

EMS WatchDog 800

  • Modulated Green-LED Light Source with 8-Year Warranty
  • Path Length of 2-15 feet (60-457 cm.)
  • Economical Reliability with Low Maintenance
  • Communications via RS485 Modbus
  • Ideal for Crematoriums, Package Boilers, Commercial Fan/Exhaust Control


Contact us to discuss the optimal solution for your monitoring needs.