HRLDSensors for particle contamination monitoring

The HIAC HRLD Series light obscuration liquid particle counting sensors use laser diode technology to measure particles from 1.2 to 600 microns in a variety of fluids. For particles of 1.2 microns and larger, light obscuration is the preferred technology. These sensors are used in a wide range of applications for contamination monitoring, such as fluid power, pharmaceutical and biotech products and precision cleaning applications. Many industries that formerly used microscopes for particle counting have turned to light obscuration sensors for increased accuracy, reliability and efficiency.

Reproducible particle counting is critical for standards such as USP <788> and ANSI/NFPA/T2.9.6R1. Typically, sample-to-sample reproducibilities of better than 10% can be expected for on-line and laboratory sampling applications.

The laser diode light source in HIAC obscuration sensors provides insensitivity to vibration as well as robust and stable illumination resulting in repeatable and accurate particle counting performance.


  • High concentration limits
  • Available in wide range of flow rates
  • Wide operating pressure range
  • On-line and batch operations
  • Calibration certificate, traceable to NIST Standards


  • Precision cleaning bath monitoring
  • Hard disk-drive component cleanliness testing
  • Filter testing
  • On-line process monitoring
  • Pharmaceutical testing USP <788>
  • On-line and laboratory condition monitoring of hydraulic fluids