Infrared Temperature Measurement | Combustion & Environmental Monitoring

Model 4500 MkIII Compliance Opacity and Dust Monitor

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Opacity and Dust Emissions Compliance Monitor

Cross-stack opacity and dust monitor

The Land Model 4500 MkIII has reset the industry standard on compliance opacity and dust concentration measurement. Combining the unique features of three patented technologies, the 4500 MkIII achieves the highest available specification for the principal performance parameters, as defined by the internationally recognized ASTM Standard D 6216-07.

Complies with QAL-1 and PS-1 - See Product Approvals for all certificates. 

System Overview

Here is a typical installation arrangement, for a Model 4500 MkIII


Options for the System

Control Room Unit

Model 4500 Control Room UnitThe Control Room Unit (CRU) provides a direct link for the operator to see at a glance the instrument readings, display warning or alarm conditions and provide a range of options including analog and digital outputs. In addition, an instrument calibration can be initiated by remote control.
The unit is simple to install and connect to the opacity monitor,using the termination box.


  • Live Information Direct from the Opacity Monitor into the Control Room or other convenient location
  • Available as 19”rack-mount configuration, includes mains power-supply
  • Uses Modbus RS 485, 2 Wire Connection to Opacity Monitor
  • Display of Instantaneous and Average Opacity, Optical Density and Dust Readings
  • 10 day Data Log available for PC download
  • Remote Calibration Initiate Function
  • Display of Instrument Warnings and Alarms
  • Calibration Status Indication
  • Optional Input/Output Module -providing 4 Analog O/Ps, 1 Digital I/Pand 15 Relay O/Ps
  • Also available for Model 9100 CO monitor

AFU & APS (optional)

The Auxiliary Functions Unit and Auxiliary Power Supply Supply (AFU/APS) provides additional communications and control facilities for the Model 4500 MkIII:

  • 2 isolated 4 - 20 mA current loop outputs
  • 2 alarm relays
  • 4 status and calibration relays
  • 4 blower status inputs
  • 4 fail-safe shutter status inputs
  • 2 fail-safe shutter control outputs
  • 4-wire Modbus port
  • RS232 or RS485 diagnostic port
  • 110 v or 230 V ac mains power supply
  • Circuit breakers and terminals for ac supply distribution

The AFU/APS connects to the Transceiver via its RS485 Modbus port.

If the AFU/APS is used to provide connections to Blowers and Fail-safe shutters, it must be located close to the 4500 MkIII Transceiver.

Air Purge Blowers

The plate-mounted blower unit is designed for vertical mounting to a stack or duct, and is available with two sizesof fan unit, to accommodate different stack pressures and instrument types.
It is suitable for either indoor or outdoor installation. An optional weatherproof cover is available for exposed locations.




Fail-safe Shutters

A signal-operated shutter unit is available for these instruments. It may be prudent to fit shutters to protect the instrument if the blower fails. These are particularly important for applications where flue gas is under positive pressure, and/or where it is very corrosive. If the air purge supply fails (normally due to mains power failure), the instrument should be removed to avoid permanent damage. With positive seal, fail-safe shutters, the instrument can normally be left in place  until the air purging is restored.

When does the shutter operate?

Shutters operate in certain conditions and depending on whether the air purge supply (normally a blower) has pressure switches fitted. The shutters will automatically re-open when the fault condition is rectified, i.e. mains power is restored or the pressure switches change state - no user intervention is required. The shutter mechanism will operate once (close and re-open) during a calibration cycle (4500 Series), in order to check that it is operating correctly. The instrument’s software will automatically trigger this operation.

Calbration Accessories

External Zero Device (EZD)
The EZD allows you to verify the zero opacity point without removing the Model 4500 MkIII from the stack. It can also be used for quarterly calibration error checks, as required by US EPA Procedure 3.

Neutral Density Calibration Filters
Filters are chosen to match your opacity monitor configuration and are calibrated as primary filters in accordance with PS-1.

Transceiver Weather covers

To be used when additional environmental protection is required. It simply hooks over the instrument, to protect from sunlight and rain. It hinges upwards for access to the instrument itself.





Calibration Stands

A set of calibration stands are important when performing a Clear Stack Calibration or Zero alignment. The instrument (to comply with US EPA Procedure 3), must be removed and attached to test stands for calibration





The standpipe welds directly to the stack for a simple, rigid mounting.
Spoolpieces are available with a wide variety of ANSI Flange sizes which can be bolted onto an existing stack flange.



Key Features

Features Benefits
Lifetime warranty on LED light source No need to replace the light source 
3-year warranty on transmissometer Worry-free operation
No continuously moving parts Highest reliability
Patented all-glass multi-prism retroreflector Lowest possible drift
Patented flood LED Maximum thermal stability
Optional fail-safe shutters Protects optics if purge air fails, and protects personnel from stack
gases during servicing
Adaptor flanges and spoolpieces Allows the 4500 MkIII to fit the existing stack flanges
Control Room Unit (option) Allows remote display and diagnostics
Single Purge Blower One blower provides purge air to transceiver and retro
Wide operating temperature range Operation -40°C to 55°C (-40°F to 131°F) is standard
Auxiliary Function Unit (AFU) Easy connections and additional I/O
Auxiliary Power Supply (APS) Universal mains power input and power distribution



Key Benefits