CEL-046 Density Measurement / Double Pass Opacity Monitor, Measures 0 - 100% Opacity & 0 - 1000mg/m3

  • In situ measurement directly in exhaust gas flow
  • Measurement reading as % Opacity and/or particulate as mg/m3
  • Modulated green LED source for long lifetime stability and immunity to ambient light
  • Rugged 316 stainless steel construction
  • Integrated visual alignment aid to simplify installation
  • In situ zero and calibration manual check facility
  • Intelligent analyser with optional DSCU operator interface with dual parameter display
  • Plug and socket connectors for ease of installation
Parameter (units) Min / Max Comment 
Measurement Performance 
Path Length, Flange to Flange (Mtr) 0.5 / 10 Flange to flange separation

Measuring Range:              Opacity (%)

              Particulate Density (mg/m3) 

0 - 100

0 - 1000

User selectable

(Optical Density also available) 

Accuracy (%) -2 / +4

Resolution:                                 (%)




Display resolution 
Damping (s)  1 / 60  Selectable 
Drift with Temperature (%) -2 / +2 Over the full operating temperature range 
Operating Wavelength (nm)  510 / 540  Green LED 
Visual Alignment Aid (%)  -1 / +1  To first target in the reticle  
Power & Air Requirements 
Voltage (Vdc)  +24  Optional 90-260 Vac PSU available  
Voltage Tolerance (%)  -10 / +10   
Nominal Current Consumption (mA)  500   
Power Up Current Consumption (mA)  500   
Air Supply Volume (L/min)  50 / 200 To each air purge body 
Air Supply Fitting    1" BSP threaded aperture in each air-purge body 
Interface Options 
Serial Comms    

ModBus RTU via RS485 (OI or TRX)

Internal USD (OI); external USD (TRX) 

Analogue Output, one (mA)  0,2,4 / 20  Isolated and scalable  
Relay Contacts, two (A)  0 / 3  @30Vdc (level alarm and data valid) 
Ingress Protection  IP65  For external use 
Ambient Operating Temperature (°C)  -20 / +55  Air temperature around the heads 
Operating Humidity (%)  100  Air humidity around the heads 
Gas Temperature (°C)  +66 

Heat insulating gaskets included

(Higher temperatures on request) 

Regulatory Compliance    

89/336/EEC Electromagnetic Radiation

72/23/EEC (Low Voltage) 

Materials:      -TRX / Reflector Heads

                                -Air Purge Bodies  

316 Stainless Steel (powder coated)

Powder coated cast aluminium (stainless steel option) 

Weight (kg)  2.5  Head plus air-purge body 
Warranty (months)  24  Return to base warranty 
Configuration Options: 

Configured with a DSCU:


Stand Alone Configuration:  


Product Description:

Ideal for monitoring levels of artificial Concept smoke and particulate levels in the exhaust gas of industrial combustion or air filtration processes.

The CEL-046 is an optical instrument designed to measure the concentration of particulate matter in an exhaust gas passing through a duct, stack or flue; typically the exhaust gas from an industrial combustion process or air filtration system.

The CEL-046 Opacity Monitor uses the double pass light transmission measurement technique, with a folded beam Transceiver / Reflector arrangement, to measure particulate, dust and smoke emissions. A light beam emitted from the Transceiver (TRX) passes across the duct, stack or flue to a Reflector, which then returns the light to the Transceiver where the intensity of the received light is measured. Increased particulate density in the stack gas attenuates the transmitted light and causes the intensity of the received light to fall. This reduction in intensity can be presented as % opacity or when calibrated against standard reference measurements, can be used to calculate the particulate concentration and present a reading in mg/m3.

The light source in the Transceiver is a high intensity, high reliability green LED which provides long life and stable intensity. The transmitted light beam is pulsed to give complete immunity to ambient light levels. The intensity of the transmitted light is monitored at source so that any variations in the emitted light level are compensated in the received signal. The Transceiver has on board temperature measurement to provide stability over the ambient operating temperature range.

The CEL-046 is an intelligent analyser which can operate as a “stand-alone” instrument consisting of the Transceiver head (TRX) and Reflector head, with all electrical connections (including outputs such as the alarm relays, 4-20 mA analogue outputs and ModBus) being made inside the TRX head. As a stand-alone instrument the CEL-046 is set-up and controlled using the supplied utility software, installed on a PC or laptop, and connected via the USB connector on the RX.

The CEL-046 is also available with the DSCU operator interface. When supplied with the DSCU all power supply and output connections are made in the DSCU rather than the TRX. The DSCU is a wall mounted control unit consisting of a numeric / directional keypad, a two line LCD display and a terminal compartment, which allows full command and control of the instrument. The DSCU is suitable for mounting locally to the instrument or remotely, such as in a control room.

The CEL-046 has no moving parts, is of rugged design and has an excellent reliability record. Regular maintenance simply involves cleaning the optical surfaces which are easily accessible due to our latched head design. Both the TRX and Reflector heads are supplied with an air purge body, which when connected to a high volume source of clean air, keeps the contaminated stack gas away for the lens surfaces. An Aluminium air purge body is available for use on standard installations and a more advanced Stainless Steel air purge body is available for more demanding installations.


Options & Accessories: 

Mounting Flange & Fixing Kit           

Product Code: CEL-ASY-067

1.5" ANSI 150 flange pattern with 240mm long extension tube (set of 2).

Fixing Kit            

Product Codes:

CEL-ASY-071 (Aluminium Air Purge Body) 

CEL-ASY-245 (Stainless Steel Air Purge Body) 

Contains M14 x 100mm studding, flat washers, spring washers and M14 nuts.

Weather Cover           

Product Code: CEL-ASY-080 

Hinged stainless steel weather / heat cover for protecting externally mounted heads.

Laser Alignment Tool           

Product Code: CEL-DSL-LAT08 

Tool to aid the alignment of the reflector head across the stack.

Blower Kit           

Product Codes:

CEL-BK-40N-110 (110v single phase)

CEL-BK-40B-240 (240v single phase) 

CEL-BK-40B-415 (415v three phase)

Blower kit for purge air.


Compressed Air Kit           

Product Code: CEL-ASY-181 

For use with compressed air purge. Includes pressure regulator, in-line filters and compressed air adapters for the purge body. 

Power / Comms Cable Assembly           

Product Code: CEL-CBL-119

2mtr cable with connector.

Outputs Cable Assembly           

Product Code: CEL-CBL-092

2mtr cable with connector.

Boxed PSU          

Product Code: CEL-PSU-005

Multi AC input, 24Vdc output 75W, IP67 rated enclosure.

Calibrated Head           

Product Code: CEL-DSL-CH350A

For use between the TRX head and the purge body to perform calibration checking.

Zero Mirror for Calibration Checking           

Product Codes: On Request

Various options available, see technical data sheet.


Span Filter for Calibration Checking       

Product Codes:

CEL-DSL-CH350S9 (Approx. Opacity 10%)

CEL-DSL-CH350S8 (Approx. Opacity 20%)

CEL-DSL-CH350S65 (Approx. Opacity 35%)

Calibrated Opacity Filters           

Product Codes:

CEL-ASY-190 (Calibration Filter, approx 8% opacity)

CEL-ASY-133 (Calibration Filter, approx 20% opacity)

CEL-ASY-183 (Calibration Filter, approx 35% opacity) 

Want more information, advice or prices? email us: info@conceptsmoke.com  

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CEL-046 - Data Sheet
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After using the Spirit 900 Smoke Generator and attending Concept's complimentary service and maintenance course:

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