Back Scattered Dust Monitor

Vasthi Instruments are global leaders in manufacturing of Back Scattered Dust Monitor and have been supplying instruments to customers worldwide, Our multidisciplinary team of scientists, physicians, engineers, and regulatory consultants with decades of global experience brings you the quintessential mechanism that provides complete safety accuracy and durability.

Vasthi Instruments was formed with visionary thinking and innovative ideas resulting in innovative products and solutions. We enhance our product quality by the continuous process of research and development. We have WIDE range of models to suite various site conditions and processes.


Vasthi Instruments Back Scattered Dust Monitor for Ideal monitoring opacity and smoke levels in the exhaust gas of industrial combustion or air filtration processes. Back Scattered Dust Monitor technology means that the ‘telescopic’ detector field of view is controlled to eliminate stray scattering from the far inside stack wall. The back scattered dust monitor is conveniently mounted on one side of the stack and usually requires no light absorber or beam dump on the opposite side of the stack. The optical parts include laser source,power control, photoelectric sensor and scattered light receiving. The 650nm laser beam sent by the laser at a tiny angle into the emission source,where it acts with the dust particles to produce scattered light. The back scattered light will be processed in the sensor into electrical signals. The circuit part will realize the photoelectric conversion,laser beam modulation, signal amplification,demodulation,light source power control, V/I conversion and HMI display. Calibrator is used to generate stable optical signals to zeroing and span calibration of the device. The Back Scattered Dust Monitor design has been implementing the thinking of “no tool” on-side installation, to minimize the complexity of field installation.

Ideal For monitoring opacity and smoke levels in the exhaust gas of industrial combustion or air filtration processes.

  • In site measurement directly in exhaust gas flow using the widely accepted light transmission technique.
  • Measurement reading as % Opacity
  • Modulated green LED source for long lifetime stability and immunity to ambient light
  • Rugged 316 stainless steel construction
  • Choice of interface options enabling easy integration
  • Free utility software for PC based setup, control, and data logging
  • Optional Operator Interface with different mounting configuration



Technical Features

  • Laser backward scattering principle can prevent the laser beam from swinging When the refractive index is uneven during the mechanical vibration at uneven temperature
  • Single-side installation without optical path alignment.
  • The on-site dispel can read the dust concentration in the field.
  • After the laser beam is modulated, the system can signicantly improve its
    anti-interference ability.
  • The device design has been implementing the thinking of “no tool” onside installation, to minimize the complexity of field installation
  • (4-20)mA standard industrial current output makes the connection easy.
  • Device overall power consumption is very low at around 3w
  • Generally, the standard setup parameters are applicable to the flue wall with a thickness less than 400 mm and a diameter greater than the device stack label size. The measuring area can be customized as required specification. Users may also adjust the area under the approval and guidance of the maintenance personnel.

Note : has adopted a 128 x 64 graphic LCD for display. The LCD contrast display adjustment can be made through adjusting a potentiometer on the front panel.

The appropriate installation is very important for its effective operation. Consultation of relative environment protection laws and regulations shall be make to elect a proper installation point before the installation, relative maintenance personnel shall also be consulted. The key factors which shall be considered are:

1) The installation position of the optical head, for which vibration, surrounding temperature, flow stability, the distance between the elbows or variable diameter at the downstream and upstream of the flow, as well as the safety of the installation and maintenance channels shall all be considered.

2) Power supply, cables, pipeline and overload protection.

3) Arrangement of the signal lines (distance, paths and interference with the other magnetic equipment).

4) People are prohibited to enter the ue/stack as they are easy to be hurt by the.

Measurement Performance

Vasthi Opacity Monitor Measurement Performance
Vasthi Opacity Monitor Measurement Performance