Linked In Facebook Twitter YouTube PUMC Blog Subscribe (203) 743-6741
PUMC Home : Product Divisions : Preferred Instruments : Product

JC-30D Smoke Opacity Monitor

Application | Overview | Features

The JC-30D Smoke Opacity Monitoring System assures an accurate measurement of smoke emissions from boilers, incinerators, kilns, and similar sources of imtermittent, visible emissions as well as an alarm contact that energizes when opacity exceeds a predetermined setpoint. The information provided encourages increased emphasis on clean, efficient combustion and effective air pollution control. Optical Sensing Assembly included.

  • Gallery

  • Application

The Preferred Instruments JC-30D Smoke Opacity Monitoring System assures an 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. Theinformation provided encourages increased emphasis on clean, efficient combustion and effective air pollution control.

Ordering Information: JC-30D Monitor, 190711 Light Source, 190712 Light Sensor, and two Light Sensor Shields 190713 are required for a complete system.

Back to top

  • Overview

The JC-30DSmoke Opacity Monitor is a microprocessor-based indicating instrument with a smoke duct mounted optical sensing assembly. The system provides a continuous opacity readout, alarm indication and shutdown capability. The smoke opacity percent is continuously displayed using a highly visible backlit LCD display. An intuitive bar graph display and alarm message provides rapid recognition of combustion conditions. All adjustments can be made directly from the faceplate of the instruments by scrolling through user-friendly, English language menus.   

The Optical Sensing Assembly consists of a Light Source and Light Sensor. These units are mounted on opposite sides of the smoke duct with the light beam focused from the source side to the sensor side. Smoke passing through the light beam reduces the intensity being received by the sensor. A signal is transmitted to the Indicating Instrument which continuously displays the percent smoke opacity and provides the alarm and control functions. This reliable single pass design requires no moving parts or complicated optical devices.   

The Light Source uses a low voltage, pre-focused, sealed beam lamp at a projection angle of 5° to reduce scattered light inaccuracies. The Light Sensor includes a solid state, photopically filtered photoelectric cell. The unit’s built-in optical “bulls eye” and variable blink rate LED assist in alignment verification. Lenses are specially designed for easy cleaning without dismantling the installed assembly.   

Operation: The indicating instrument continuously displays the percent smoke opacity and provides the following alarm and control sequences. Typically the JC-30Dalarm relay activates an external alarm bell or horn and the shutdown relay is used to shut down the burner. 

Automatic Calibration: The JC-30Dincludes a 120 Vac input that monitors the burner fan starter coil and initiates an Automatic Calibration cycle whenever the burner fan stops running (ensuring a clear stack condition). This prevents nuisance burner trips due to dust build-up. “WARNING: CLEAN LENSES NOW” is displayed when the dust level is high. At the completion of the Calibration Cycle, the JC-30Dturns off the light source until the fan restarts, extending the life of the bulb. A Calibration Cycle can also be manually initiated from the JC-30DMenu (after a lens cleaning, re-alignment, etc.) 

“Standard” Operating Sequence:

  • Smoke Opacity Exceeds Setpoint: Bar graph blinks and “ALARM” message appears.
  • After 20 Seconds “smoke-puff” Delay: Alarm relay (K1) contact activates, the remote alarm bell or horn is activated. Pressing the Alarm Silence button de-activates (K1) relayand the external bell or horn.
  • Smoke Opacity Continues For 120 Seconds (adjustable): The shutdown relay (K2) activates in manual reset mode, “SHUTDOWN” message appears, and the (K1) relayreactivates. When the smoke opacity condition clears, the JC-30DRESET pushbutton must be pressed to reset the shutdown relay in order for the burner to re-start.
  • Smoke Opacity Returns to Normal: “ALARM” message disappears.

“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 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 setpoint, the (K2) relay remains activated for an additional 180 seconds (adjustable) to help prevent a reoccurrence of excessive smoke.

Back to top

  • Features
  • RS485 Modbus Communication
  • 4-20 mADC Retransmission
  • 4 Digit Display, 200 Segment Bar Graph
  • Large LCD Graphic Display
  • Single Pass Design, No Moving Parts
  • Field Adjustable Using English Language Menus
  • Automatic Calibration When Burner Cycles Off
  • 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


Power Supply: 120 VAC 50/60 Hz, 15 VA

Case Size: 8"H x 3.5"W x 7.5"D

Enclosure Type: NEMA 4 Faceplate, Flush Mounting

Ambient Temperature: +32° to +122° F Ambient

Digital: High Contrast LCD Display 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:

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 mADC, 650 Ohm Load Max

Network Output: 1200-38400 Baud, RS485 Modbus, ASCII or RTU 

Back to top