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Modular stack gas monitor

SM-4 mobile

Monitoring of Mercury Emissions
at different sites

Introducing the new SM-4 mobile

  • Easy to transport
  • Qickly dismountable 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
Mercury Instruments

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.

SM-4 mobile Transport

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

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

Mercury Instruments

Modular Stack Gas Monitor SM-4 mobile: Technical Specifications

Measurement technique:   Dilution probe with thermo-catalytic converter at stack, fast loop to analyzer unit, atomic absorption detector with Gold Trap
Principle of measurement:  Cold Vapor Atom Absorption Spectrometry (CVAAS) with Amalgamation,
wavelength 253.7 nm
Measured component:  HgT (total mercury)
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:   250 °C
Ambient temperature range allowed: 
-5 °C to 40 °C
Sample line length: up to 90 m
Signal output:  4-20 mA (500 Ω max.); RS232 serial; Modbus RTU/RS485 (option);
Ethernet (option)
Status output: 3 x pairs of relay contacts (dry contacts)
Remote access: Modem and SM-4 software (option)
Voltage:  230 V (110 V optional); 50/60 Hz
Electrical power consumption:  Analyzer cabinet: 450 VA;
Air conditioning cabinet: 1000 VA;
Heated sample line: 30 VA per meter
Dimensions: Analyzer cabinet: 60 x 60 x 60 cm (H x B x T)
Air conditioning cabinet: 73 x 60 x 60 cm (H x B x T)
Probe: 75 x 38 x 34 cm (H x B x T)
Probe controller48 x 44 x 27 cm (H x B x T)
Weight: Analyzer cabinet: 50 kg
Air conditioning cabinet: 50 kg
Probe converter unit: 28 kg
Probe controller: 14 kg
Air consumption: 6 bar (87 PSI); peak 35 l/min (1.2 scfm)r)
Calibration/span check:  Automatically, with integrated calibration gas generator (NIST certified).
automatically, with integrated calibration gas generator for ionic Hg (optional);
manual, heated fitting for connection of a calibration gas source
(e. g. HOVACAL®) available.
Mercury Instruments As a leading supplier of high precision analytical equipment, we strive at all times to offer top quality solutions. Our products are manufactured according to the ISO 9001 quality regulations.


SM-4 mobile

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