A robust near infrared (NIR) process spectrometer for analyzing liquids.

Rugged, fast, and maintenance-free, the MicroNIR PAT-L transmission spectrometer is designed for real-time process monitoring in industrial and pharmaceutical process analytical technology (PAT) applications.


The PAT-L is the newest member of the VIAVI PAT family of miniature process spectrometers. Its compact design and high performance make it ideal for use in industrial processes that require continuous monitoring. The NIR transmission design permits analysis of aqueous and nonaqueous liquids. The PAT-L is available in multiple configurations, specified on order, with a choice of probe material, optical path length, immersion depth, and process flange. As a member of the MicroNIR product family, it enables moving directly to production chemometric models and processes developed elsewhere. The PAT-L integrates readily with process equipment of all types and sizes, with the performance and stability to support truly efficient – and scalable – manufacturing.


  • All-in-one optical design for ease of installation and cleaning
  • Continuous liquid process monitoring in vessels, tanks and pipelines
  • Rapid acquisition time for real-time reaction monitoring and high flow liquid streams
  • Wide range of transmission path lengths for organic solvents and aqueous solutions
  • Full integration of light source and light pipe eliminates fiber optics
  • Broadly configurable to meet the needs of most processes
  • Optional cooling jacket for high temperature environments
  • USB-powered via hardwired cable
  • Includes MicroNIR Pro software, a complete data acquisition and chemometric modeling package

Pharmaceutical Manufacturing

  • API synthesis
  • Solvent moisture content
  • Biofermentation nutrition monitoring

Polymerization Process Monitoring

  • Polyol hydroxyl number
  • Polyurethane and polyisocyanate condensation

Oil & Gas

  • Octane number
  • Lubricant properties
  • Fuel identification

Industrial Applications

  • Semiconductor cleaning fluids
  • Reaction monitoring
  • Detergents, paints and coatings

The MicroNIR PAT-L immersion spectrometer is based on the MicroNIR PAT-U process spectrometer, with design  adaptations that include:

  • Full integration into a fixed gap immersion probe
  • High-efficiency light pipe design
  • Inert gas backfill eliminates water vapor interference and condensation
  • Hardwired USB cable for reliability
  • Optional removable cooling jacket

The PAT-L is a fully integrated spectrometer-probe. The spectrometer section is rated IP65/IP67 and the immersion probe section is rated at up to 250 bar and 400 ºC.  Optical specifications are identical to the MicroNIR PAT-U and may be found on the PAT-U Data Sheet. The cooling jacket, with hose barb connections, allows coolant to circulate and maintain the spectrometer within its operating temperature range of 0 to 50ºC while the probe is in contact with hot fluids or in high ambient temperatures. Maximum working temperatures depend on the probe length and material and the coolant used. The PAT-L immersion probe section is based on the Hellma Excalibur HD FPT 26, a well-proven, heavy-duty industrial probe equipment.


Like all MicroNIR instruments, the PAT-Lx includes the VIAVI MicroNIR Pro software suite with features for data acquisition, calibration and method development, user management, and real-time prediction. MicroNIR Pro software supports instrument qualification (IQ/OQ) per EP 2.2.40 and USP 1119/1856 test criteria and software tools to meet rigorous Title 21 CFR Part 11 compliance. An enhanced OPC interface is optionally available for integration with process control systems.

Mounting and Process Integration

The MicroNIR PAT-L has been designed for maximum flexibility to meet the diverse requirements of process integration. A variety of flange mounts and probe lengths are available. Probe body materials include 316L stainless steel and Hastelloy C22. Transmission gaps range from 2 mm (for aqueous liquids) to 3, 4, 5 and 10 mm (for polymers and petrochemicals).

The MicroNIR PAT-L can be mounted to standard sanitary flanges using a collet assembly and tri clover clamp, or via flange if so equipped. Installation in hazardous locations requires trained and/or certified personnel and must conform to local regulations.

  • MicroNIR PAT-Lx Configurations

    The MicroNIR PAT-Lx for hazardous locations consists of two main parts: The instrument head with probe and the barrier box, connected by a hardwired USB cable . The instrument head is identical to the MicroNIR PAT-L and consists of a spectrometer section and a probe section with integrated light pipe. The probe operates in transmission mode with an optical path length (gap) specified when purchased. The barrier box houses the interface electronics in a heavy, ruggedized cast aluminum enclosure. The barrier box has user-available ports for connections to Ethernet, 24 V DC power, and optional external trigger, using customer-supplied connections rated for hazardous locations. The barrier box comes with mounting brackets for attachment to process equipment.

    Probe material*

    • Stainless steel 316L
    • Hastelloy C22

    Optical path length (gap), mm*

    • 2, 3, 4, 5, or 10 mm

    Maximum insertion depth*

    • 240, 440, 640, or 940 mm without flange
    • 100 to 900 mm with flange

    Process connection*

    • Various EN, ASME, and other flanges available, see price list

    Maximum temperature and pressure ratings

    • Up to 400°C and 40 bar
    • Dependent on material and flange, see price list


    • Class I Div. 2 Zone 1 and 2
    • Class II Div. 2 Zone 21 and 22 Class I
    • Groups C and D
    • Class II Groups E, F, and G