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Modular Stack Gas Monitor
SM-4 mobile


Automatic monitoring of total mercury emissions (CEM) at different sites


SM-4 mobile


Introducing the new
SM-4 mobile


moving the SM-4 mobile


  • Easy to transport
  • Qickly dismounted and reassembled
  • Sample dilution directly at the probe: eliminates interference with virtually any sample matrix
  • Maintenance free low temperature converter directly at stack: no transport of ionic mercury thus minimizing mercury adsorption
  • Detects total mercury
    (elemental, ionic and bound mercury)
  • Automatic calibration for elementary and ionic Hg
  • Automatic quality control (QAL3) during operation
  • Extremely wide range of measurement:
    0,05 bis 1000 µg/m³


The SM-4 mobile by Mercury Instruments was developed on the basis of the well proven SM-4 Stack gas monitor. Its measurement principle and technique, its thermocatalytic reactor, the detector and the sample probe are identical with those of the stationary SM-4.


Tansport SM-4 mobile


Due to its modular design, the SM-4 mobile can easily be transported, assembled and disassembled. It is the ideal solution for the determination of total vapor phase mercury emissions at varying sites.




  • Coal fired power plants
  • Waste incineration plants
  • Sewage sludge incineration plants
  • Cement kilns
  • Recording of Hg-emission situations as well as determination of the efficency of
    Hg-reduction techniques
  • Method 30A applications
  • Testing of stationary CEMs
  • Optimizing of mercury control technologies

SM-4 mobile applications


An example:

link zu MI-News Salvador, Brasil

Benefits of the SM-4 mobile


  • Modular construction
  • Easy to transport
  • Thermo-catalytic sample gas treatment, no reagents needed
  • Thermo-catalytic converter operating at low temperature (200°C)
  • Sample gas dilution avoids interferences
  • No generation of liquid waste or condensate
  • Extreme high sensitivity: low measuring range is 0.05 µg/m³
  • Heated particle filter with automatic cleansing
  • Fast response: t(90) time typically 180 sec
  • Length of sample line up to 100 meters
  • Integrated source of calibration gas for ionic mercury
  • Automatic quality control (QAL3)
  • Maintenance free

System components


  • Sampling probe with dilution and converter unit
  • Probe controller box
  • Heated bundle containing sample line, air supply line, calibration gas feed line
  • Analyzer cabinet with detector and calibrator und Druckluftaufbereitung
  • Air conditioning cabinet with pressure gauges, air filters, membrane dryer


SM-4 mobile System components


SM-4 mobile:
Technical Specifications


Measured component:

Total mercury (ionic and elemental speciation as option)

Measurement principle:

Dilution probe with thermocatalytic converter at stack,
Amalgamation (MI GoldTrap),
Cold Vapor Atom Absorption Spectrometry (CVAAS),
Wavelength = 253,7 nm

Measuring range:

0,05 μg/m³ to 500 μg/m³ Hg

Detection limit:

0,0001 μg/m³ (Detector);
< 0,01 μg/m³ (System)

Response time:

Typically 180 sec

Max. sample temperature:


Ambient temperature range allowed:

-5°C to 40°C

Sample line length:

up to 100 m

Signal outputs:

  • analogue: 4-20 mA (500 Ω max.)
  • serial: RS 232
  • Modbus RTU/RS485 (option)
  • Ethernet (option)

Status output:

3 x pairs of relay contacts (dry contacts)

Remote access:

Modem and SM-4 software (option)

Power supply:

230 V / 50 Hz;
(110 V / 60 Hz option)

El. power consumption:

Analyzer cabinet: 450 VA;
Air conditioning cabinet: 1000 VA;
Heated sample line: 30 VA per meter


Analyzer cabinet:
60 x 60 x 60 cm (H x W x D)
Air conditioning cabinet:
73 x 60 x 60 cm (H x W x D)
75 x 38 x 34 cm (H x W x D)
Probe controller:
48 x 44 x 27 cm (H x W x D)


Analyzer cabinet: 50 kg
Air conditioning cabinet: 50kg
Probe converter unit: 28kg;
Probe controller: 14 kg

Air consumption:

peak 35 l/min, 6 bar (87 PSI)


  • automatic, with built in calibration gas generator for elementary Hg (option)
  • automatic, with built in calibration gas generator for ionic Hg (option)
  • manual, with built in heated fitting for feed of externally provided calibration gas (e.g. HOVACAL®)

As a leading supplier of high precision analytical equipment, we strive at all times to offer top quality solutions. Our quality management system is certified according to ISO 9001.

SM-4 mobile cover

Download brochure:

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