Pollution Monitoring Equipment

DT109 Opacity Monitor

The Model DT109 is the perfect solution for monitoring visible emissions where a compliance system is not required. Has many applications other then stacks such as dust from conveyor systems.


The Model DT109 allows for continuous monitoring of emission levels which helps you stay below EPA limits at all times. When bags become worn or ripped, there is an immediate alarm and indication in the recorder reading.

The Model DT109 is perfect for applications where multiple ducts lead to a common stack. Since the Model DT109 measures opacity, this instrument will alert your operators to a possible over emission problem or even a boiler upset that could cause a violation of your emissions standards.


  • Measures opacity as well as mass emissions
  • Process monitoring with instant and average 4-20 mA outputs
  • Modbus RTU Interface
  • RS232/422/485 serial port available

Model DT109D (Transceiver and Retro-reflector)

  • Double pass
  • Spans up to 10 feet
  • High accuracy

Model DT109S (Separate Transmitter and Receiver)

  • Single pass
  • Spans up to 40 feet
  • High accuracy

Easy to install, easy to use

The DT109 system is easily installed using the provided duct mounting hardware. Standard signal cable is used to connect the transmitter/receiver to the panel mount control unit. A front panel mounted backlit LCD display shows all critical information as well as over emissions, blower failure, and lamp out conditions. Adjustment of zero, using the keypad during a clear stack condition, is all the maintenance normally required.

High reliability, pinpoint accuracy

The DT109 system uses a single light source taking the intensity of the light beam passing through the duct and comparing it to the light output from the lamp to make its measurement. This cancels out any variations due to line voltage changes and tungsten loss in the lamp assuring you steady, reliable performance year after year.

Low level Measurements

The Model DT109 measures sudden changes of emission with a high degree of sensitivity and accuracy.



Measurement System

Angle of view and projection:
Light Source:
Operating Principle:

Path length:
Response Time:
Spectral response
Power Supply:

4° maximum (full angle)
Tungsten lamp, average life 3 years
Cross stack, dual or single beam.
DT109D double pass, DT109S Single pass
Spans 109D up to 10 ft., 109S up to 40 ft.
Less than 10 seconds
400 to 700 nanometers at the 10% points
105-130V AC. 50/60 Hz 230 VAC 50/60 hz optional

Purge Air Blower System (800-31/32)

Voltage / Current:

115/230V AC. 50/60 Hz. / 3.4/5 Amps.
75/80 lbs.


Electronics Operating Temp:
Max Flange / Stack Temp:
Relative Humidity:

-50 °F to 150 °F (Process up to 1500 °F.
600 °F- Flange mounted on thermal insulators / Up to 1500°F.
95%, noncondensing

Control Unit

Ambient Operating Temp:
Analog Outputs:
Audible Alarm:
Power Supply:
Relay Outputs:
Relay Rating:
Status Indicators:
Transmitter to sensor

20 °F to 125 °F
4-20 MA, Modbus RTU serial RS232, 485, or 422.
Piezo electric buzzer.
Panel mount 91/2” x 7” x 14” NEMA 4 wall mount 10” x 12” x 6”
80 Character backlit LCD with adjustable contrast control.
Panel mount (NEMA 4 available)
Microprocessor based with analog I/O, digital I/O and serial capabilities.
Remote trigger for calibration cycle.
7 pre-configured keys for data input.
Surface mount.
115V +/- 10%, 25W (230V optional)
Dry contacts for Cal Mode, Pre-emission, Over-emission, Fault, more…
1 A at 24 VDC, 1 A at 125 VAC.
Lamp out, blower out, pre-emission alarm, and analog signals

200 ft. Max. Consult factory for greater distances

For more technical information, fill out our online information request form or contact us.