Vaisala K-PATENTS® SAFE-DRIVE™ Process Refractometer PR-23-SD


Brochure (PDF)
Product Manual (PDF)
Instrument Verification (PDF)
Prism Wash (PDF)
SAFE-DRIVE™ Best Practices Generation 2.1 (PDF)
User Training on Safe Use of SAFE-DRIVE™ Process Refractometer PR-23-SD (PDF)
Training Order Form for User Training on Safe Use of SAFE-DRIVE™ Process Refractometer PR-23-SD (PDF)

    SAFE-DRIVE™ Operation Guide Videos:


Vaisala K-PATENTS® SAFE-DRIVE™ Process Refractometer PR-23-SD is a retractable refractometer for measuring black liquor dry solids and green liquor density or TTA in kraft chemical recovery process.

Vaisala K-PATENTS® SAFE-DRIVE™ Process Refractometer PR-23-SD system consists of:

  • Retractable SAFE-DRIVE™ Process Refractometer Sensor
  • SAFE-DRIVE™ Isolation Valve
  • SAFE-DRIVE™ Retractor
  • Steam Wash System
  • Indicating Transmitter

Vaisala K-PATENTS® SAFE-DRIVE™ design allows for safe and easy insertion and retraction of the sensor under full operating pressure without having to shut down the process (Patent No. US 7631569).

The measurement range covers 0-100 % by weight. The accuracy is typically ±0.1 % b.w. and the measurement is automatically temperature compensated. Low and high concentration alarms can be configured. Because of the digital sensing technology, even large amounts of suspended solids, bubbles or color changes do not affect the measurement or the accuracy.

Key Features:

  • SAFE-DRIVE™ isolation and retractor allow for safe and easy insertion and removal of the refractometer sensor under full process pressure. Easy-to-place and self-retaining design. Triple sealing by two lip seals and an O-ring.
  • Accidental opening or closing of the isolation ball valve is prevented.
  • The retractable prism wash nozzle can be safely removed for a service check.
  • SAFE-DRIVE™ retractor protects the user from accidental spills during retraction and insertion.
  • The SAFE-DRIVE™ sensor is very easy to install to any pipe size (2 inch...24 inch) by welding or via a spool piece (diameter 2 inch...20 inch). Can be mounted either on horizontal or vertical pipe lines. Maximum static pressure is 40 bar, maximum operating pressure is 10 bar. Spool piece process connection is DIN-flange PN25/ANSI-flange 150 lbs.
  • Calibration is identical for any SAFE-DRIVE™ sensor: Refractive Index (nD) 1.3200 – 1.5300, which corresponds to 0-100 Conc at 100°C (212°F). Therefore, all sensors can be freely interchanged without optical calibration or parameter changes.
  • Process temperature range: -20° – 170°C (-4° – 340°F)
  • Dual connectivity: one transmitter can operate two sensors independently. A second sensor can be easily integrated later.
  • Completely digital system: particles and bubbles do not affect operation or accuracy.
  • Patented CORE-optics module: no drift, no re-calibration, no mechanical adjustments.
  • Ethernet connection and remote panel through Internet allow for data-logging and remote operation, e.g. review instrument data and diagnostics.