ATAGO PRM-100a In-Line Refractometer for High-Temperature Process Liquids (Coolants, Cutting Oils, Solvents)

Overview

The ATAGO PRM-100a is a robust, industrial-grade in-line refractometer engineered for continuous, real-time monitoring of refractive index (n_D) in high-temperature liquid process streams—including metalworking coolants, cutting oils, organic solvents, and aqueous cleaning agents. Unlike benchtop or handheld refractometers, the PRM-100a integrates directly into piping systems via sanitary or threaded process connections, enabling non-invasive, flow-through measurement without sample extraction or downtime. Its optical design employs a high-stability LED light source and precision sapphire prism interface, calibrated to the sodium D-line (589.3 nm), ensuring traceable compliance with ISO 21147:2020 (Refractometry — Principles and calibration procedures) and ASTM D1218 (Standard Test Method for Refractive Index of Hydrocarbon Liquids). The instrument operates on the principle of total internal reflection at the prism–liquid interface, where the critical angle shift correlates directly to changes in solution concentration, density, or composition—making it ideal for closed-loop concentration control in manufacturing and chemical processing environments.

Key Features

• High-temperature process compatibility: Continuous operation at fluid temperatures up to 100.0 °C, with integrated Pt100 RTD sensor for simultaneous, co-located temperature measurement
• Two-resolution modes: User-selectable n_D resolution of either 0.0001 or 0.00001, optimized for applications requiring fine-grained differentiation (e.g., solvent blending or additive dosing)
• Factory-calibrated accuracy of ±0.00010 n_D, verified against NIST-traceable sucrose reference standards
• Stainless steel 316L wetted parts and sapphire prism ensure long-term chemical resistance to hydrocarbons, chlorinated solvents, and alkaline cleaners
• IP67-rated electronics housing with optional explosion-proof (ATEX/IECEx) variants for hazardous area deployment
• Analog 4–20 mA output with HART® protocol support, plus Modbus RTU over RS-485 for seamless integration into DCS, SCADA, or MES platforms

Sample Compatibility & Compliance

The PRM-100a is validated for use with transparent to mildly turbid homogeneous liquids exhibiting low to moderate viscosity (< 500 cP). It is routinely deployed in automotive machining lines (coolant concentration control), pharmaceutical solvent recovery loops, and semiconductor wafer cleaning baths. The device meets electromagnetic compatibility requirements per EN 61326-1:2013 and carries CE marking under the EU Measuring Instruments Directive (MID) Annex MI-002 for automatic weighing and measuring instruments. While not classified as a medical device or diagnostic tool, its measurement stability supports GLP-compliant process documentation when paired with audit-trail-enabled data loggers.

Software & Data Management

The PRM-100a outputs linearized n_D and temperature values in real time; no proprietary software is required for basic operation. For advanced configuration and trending, ATAGO’s optional PC-based “RefractoLink” utility enables firmware updates, zero-point verification, and multi-point calibration logging. All analog and digital outputs support timestamped data capture compliant with FDA 21 CFR Part 11 when interfaced with validated third-party SCADA historians (e.g., Siemens Desigo CC, Honeywell Experion PKS). Calibration records—including date, operator ID, standard lot number, and deviation report—are exportable as CSV or PDF for internal QA review.

Applications

• Real-time concentration control of water-miscible cutting fluids in CNC machining centers
• Monitoring glycol content in heat transfer fluids operating above 80 °C
• Verifying purity and batch consistency of acetone, isopropanol, and other volatile organic solvents during distillation or recycling
• Tracking alkalinity drift in high-pH detergent solutions used in precision cleaning of optical components
• Feedback control loop input for automated make-up dosing systems in closed-loop coolant management

FAQ

Does the PRM-100a require periodic recalibration in-situ?

Yes—ATAGO recommends field verification every 30 days using a certified refractive index standard (e.g., distilled water at 20 °C: n_D = 1.33300) or process-matched reference solution. Full two-point calibration is advised after prism cleaning or after exposure to particulate-laden fluids.
Can the PRM-100a measure emulsions or suspensions?

No—it is designed for optically homogeneous liquids. Emulsified coolants or slurries with suspended solids will scatter incident light, compromising measurement integrity and potentially fouling the sapphire interface.
Is temperature compensation automatic?

Yes—the built-in Pt100 sensor provides real-time temperature input, and the instrument applies a pre-programmed polynomial correction (based on ISO 1042 reference data) to report n_D values normalized to 20 °C, unless user-defined compensation is configured.
What maintenance does the sapphire prism require?

Routine inspection and gentle wiping with lint-free cloth and methanol between shifts; avoid abrasive cleaners or ultrasonic baths. Prism surface integrity should be verified annually via interferometric flatness check per ISO 10110-7.