Smoke Opacity Monitoring System


The JC-30D2-EZ Smoke Opacity Monitoring System assures accurate measurement of smoke emissions from boilers, incinerators, kilns, and similar sources of intermittent, visible emissions as well as an alarm contact that energizes when opacity exceeds a predetermined setpoint.  Equipped with the updated automatic opacity calibration, allowing the JC-30D2-EZ to calibrate without the need of personnel. The information provided encourages an increased emphasis on clean, efficient combustion and effective air pollution control. Optical Sensing Assembly included.

  • Auto-Calibration after each burner post-purge
  • Automatic Calibration When Burner Cycles Off — explanation video here
  • RS485 Modbus Communication
  • 4-20 mA Retransmission
  • 4 Digit Display, 200 Segment Bar Graph
  • Single Pass Design, No Moving Parts
  • Field Adjustable Using English Language Menus
  • Early Warning Message and Relay Contact For Deteriorating Combustion Conditions
  • Burner Safety Shutdown Message and Relay Contact
  • Three Alarm Sequences: Standard, NYC BAR, Wood / Coal Overfire Air Fan

New Features: 

  • Modbus TCP/IP ethernet communications, in addition to the existing RS-485.
  • Controller depth is 4.88” for shallow panel mounting. Compare to 7” depth on the old controllers.
  • Color touchscreen, similar to the PCC-IV.
  • Plug-in wiring terminals for quick controller replacement.
  • Firmware updating in the field via JCD2_Edit and USB port.
  • Up to 50 historical alarm and event messages with time/date.
  • Overview and Features
  • Application
  • Specifications
  • Documents
Overview and Features

The JC-30D2-EZ Light Source and Light Detector are mounted on opposite sides of the smoke ducts. Smoke passing through the light beam reduces the light intensity sensed at the Detector. The intensity signal is transmitted to the JC-30D2 Indicator where it is converted into Opacity for display and alarming.

Light Source and Sensor

The 190851S Light Source uses a long-life LED Lamp. The 190851D Detector has a large lens that dramatically reduces inaccuracies due to ambient light and misalignment.


Calibration is automated, there are no manual adjustments. During every Calibration, the Lamp brightness is automatically adjusted to suit the soot/dust build-up, alignment changes, and stack width.


The JC-30D2-EZ can be configured to automatically do a calibration after the burner fan cycles Off. Calibration cancels out soot build-up on the optics and thus significantly reduces the need to frequently clean the Source window and the Detector lens. Auto-Cal reduces false alarms caused by typical burner light-off and shutdown soot deposits.

JC-30D2-EZ Indicator / Alarm: At a glance, the bar graph indicates when maintenance is required before the burner shutdown occurs. Intuitive Menu navigation makes setup and adjustments easy. RS-485 Modbus makes remote monitoring easy.

 “NYC BAR” Sequence: This sequence is similar to the Standard Operating Sequence (above), but conforms to the New York City D.E.P. Bureau of Air Resources requirements. The (K1) relay activates instantly and the (K2) relay delay is fixed at 120 seconds (not adjustable). The 190712 Light Sensor Alarm Test filter complies with NYC BAR requirements. 

“Wood / Coal” Overfire Air Fan Sequence: This sequence is used with stoker fired boilers. See the Standard Operating Sequence (above) for (K1) relay and Alarm Silence button operation. The (K2) relay is used to reduce the opacity by activating an overfire air fan or damper. When opacity has been above setpoint for 15 seconds (adjustable) the overfire air relay (K2) activates and a “FAN ON” message appears. When the smoke clears and drops below the setpoint, the (K2) relay remains activated for an additional 180 seconds (adjustable) to help prevent a reoccurrence of excessive smoke.


The Preferred Instruments JC-30D2-EZ Smoke Opacity Monitoring System assures accurate measurement of the smoke emissions from boilers, incinerators, kilns, and similar sources of intermittent, visible emissions. Typical applications include commercial buildings, schools, hospitals, apartment complexes, and industrial plants. The information provided encourages increased emphasis on clean, efficient combustion and effective air pollution control.


Ordering Information: JC-30D2-EZ Monitor, 190851S Light Source, 19085D Light Sensor.



Power Supply: 120VAC +/-15%, 50/60 Hz, 26 VA

Case Size: 3 1/2 w x 7 9/16 h x 4 7/8 d

Enclosure Type: NEMA 12 Faceplate, Flush Mounting

Ambient Temperature: 32°-131° F (0°-55° C) Ambient

Digital: Color Touchscreen 4" High, 0.5% Resolution Bar Graph


Alarm Setpoints: Adjustable 5-50% 

Light Source and Light Sensor

Calibration: Automatic, Off-Line

Spectral Response: PhotopicPeak and mean within 500-600nm

Angle of Projection: <5°

Operational Error: <5%

Span Drift: <2%

Zero Drift: <2%

Calibration Error: <1% (Linearity)

Response Time: < 10 seconds for 95% change

Sighting Distance: 1 to 8 Foot Smoke Duct, 3 to 10 Foot Optical Path Length

Wiring Distance: 500 FT. Max (16 Ga. Wire), 250 ft. Max (20 Ga. Wire)

Sensor Housing: ¾" Pipe Mount 


Relay Outputs: Two SPDT Relays, 10 A Resistive, 8 FLA, ½ HP, 120 VAC

Retransmission: 4-20 mA, 650 Ohm Load Max

Network Output: 4800-57600 Baud RS485 Modbus RTU, Ethernet TCP/IP


Smoke Opacity Monitoring Specification

Smoke Opacity Monitoring Instruction Manual

Smoke Opacity Monitoring Cutsheet

Smoke Opacity Monitoring Brochure