All Portable GRIMM Occupational Dust Monitors deliver single particle counts and size classifications in real time.

(1) The air sample in form of various sized particles is constantly being drawn via a volume controlled pump (3+4) through a flat beam of light which is produced by a (6) focused laser diode (5). Each scattered signal generated crossing this beam is detected with a high speed photo di-ode (8), at 90° so the particle color changes can be neglected. This pulse is analyzed by an integrated pulse height analyzer (9) and is classified in 8 (or 15) different size ranges (10) and then counted. These counts or masses (per size range) are stored on the data storage card (11) and are displayed in intervals every six seconds (or minute) on your display (12) as:

  •  Single-Particle Counts up to very high concentrations of 2.000.000 particles/l. without range change or dilution. 

  • In this mode the unit is mainly used as a single particle counter for gray rooms and for industrial process control. 

  • Dust Mass Distribution displaying results (like an impactor) in 8 (or 15) different size ranges from 0.001 up to 100mg/m3 . 

  • Occupational Dust Mass simultaneously displaying in accordance to EN standard mentioned at left the inhalable, thoracic and alveolic masses ranging from 0.001 to 100 mg/m3. 

  • Instrument performance data are also be written to the instrument's internal memory and are on hand from the removable data storage card.   In addition a filter is incorporated (2) collecting ALL the measured dust, so that at any later date an appropriate density verification/correction is possible. This removable 47mm PTFE membrane filter is also the base for legal mass monitoring and is in accordance to many national and ISO standards.

 Field  mass calibration to local dust conditions can be achieved anywhere in the world by simply removing the above shown filter. Through weighing the filter you awaken the possibility to make specific density corrections in conjunction with the calculated instrument mean dust mass of the area in which you have monitored.

 concept of a typical GRIMM dust monitor

Professional Dust Monitoring requires that the following conditions are taken into consideration: 

  • The sampling method (1) must be in accordance to the application to ensure proper collection and reproducibility, more details are outlined on page 5.

  • A precision laser with high quality quartz collimators (6) must be present guaranteeing exact particle size identification in the15 different size variations at different temperatures.

  • Accurate mass calculation via multiple particle sizing (µC), assuring precision in all modes. This eliminates the need for a size specific impactor or cyclone at the sample inlet.

  • Contamination protection of the optical chamber by a continuous clean sheath of air at the optic. In order to avoid signal drift due to dust mass agglomeration inside, the instrument has a delayed start and stop cycle.

  • A constant sample flow (3+4) although the dust load on the filter permanently increases with time. The sample flow is fixed at 72 liters/hour and maintained by an internal flow controller.

  • A vibration insensitive optical bench (5-7) system integrated in rigid construction to ensure the same accurate reading in the field.

  • Remote data acquisition (11) via PCMCIA modem card is available and enables data transmission via cellular and/or telephone land lines. 

  • Low maintenance cost by use of standard commercial power and filters sources