ATAGO PAL-91S Ethylene Glycol Antifreeze Freeze Point Refractometer
| Brand | ATAGO |
|---|---|
| Origin | Japan |
| Product Type | Handheld Refractometer |
| Model | PAL-91S |
| Measurement Range | Ethylene Glycol: 0.0–90.0% w/w |
| Freeze Point Temperature | 0 to −50 °C |
| Accuracy | ±0.4% (0–15%), ±0.6% (15–22%), ±0.7% (22–55%), ±0.8% (55–90%) for EG |
| Temperature Compensation | Automatic (ATC), 10–100 °C |
| Resolution | 0.2% |
| Display | Digital LCD |
| IP Rating | IP65 |
| Power | Two AAA batteries |
| Dimensions | 5.5 × 3.1 × 10.9 cm |
| Weight | 100 g (instrument only) |
Overview
The ATAGO PAL-91S Ethylene Glycol Antifreeze Freeze Point Refractometer is a precision handheld optical instrument engineered for rapid, field-deployable quantification of ethylene glycol (EG) concentration and corresponding freeze point temperature in aqueous coolant solutions. Based on the principle of critical-angle refractometry, the PAL-91S measures the refractive index of the sample at ambient or process temperature, then applies empirically validated calibration curves—specifically optimized for ethylene glycol–water binary systems—to simultaneously derive both mass fraction (% w/w) and theoretical freezing point (°C). This dual-scale output eliminates the need for manual lookup tables or secondary calculations, enabling immediate operational decisions in automotive maintenance, HVAC system commissioning, solar thermal installation, and industrial heat transfer fluid management. The device operates without external power sources beyond standard AAA batteries and requires no solvent rinsing between measurements—only a single drop of sample applied to the prism surface.
Key Features
- Simultaneous dual-scale digital readout: ethylene glycol concentration (0.0–90.0% w/w) and calibrated freeze point (0 to −50 °C)
- Automatic temperature compensation (ATC) across 10–100 °C, ensuring measurement stability under variable ambient conditions
- High-reproducibility optical design with sapphire-coated prism and LED illumination source for long-term drift resistance
- Rugged, sealed housing rated IP65 for dust and water jet resistance—suitable for workshop, field, and outdoor use
- Compact ergonomic form factor (5.5 × 3.1 × 10.9 cm; 100 g) with intuitive one-button operation and auto-hold function
- No consumables, reagents, or calibration fluids required—zero maintenance beyond routine prism cleaning with lens tissue and distilled water
Sample Compatibility & Compliance
The PAL-91S is validated exclusively for ethylene glycol–water mixtures. It is not intended for propylene glycol, methanol, glycerol, or multi-component antifreeze formulations containing corrosion inhibitors, dyes, or surfactants—such additives may alter refractive behavior and invalidate factory calibration. For regulatory traceability, the instrument complies with JIS K 0061 (Japanese Industrial Standard for refractometric analysis) and supports GLP-compliant documentation when paired with ATAGO’s optional data logging accessories. While not FDA 21 CFR Part 11–certified as a standalone unit, its measurement outputs are suitable for inclusion in quality records where freeze point verification is specified per ASTM D1177 or ISO 22883 for engine coolant testing.
Software & Data Management
The PAL-91S operates as a self-contained measurement endpoint with no embedded memory or Bluetooth/Wi-Fi connectivity. All data acquisition is manual: users record displayed values directly into logbooks or LIMS-compatible spreadsheets. For laboratories requiring audit trails, ATAGO recommends pairing the PAL-91S with the optional PAL-ES data transfer kit (sold separately), which enables USB-based export of timestamped readings to CSV files. These exports include instrument ID, measurement date/time, EG %, freeze point, and ATC-corrected temperature—supporting alignment with ISO/IEC 17025 documentation requirements for calibration and testing laboratories.
Applications
- Preventive maintenance of automotive and heavy-duty vehicle cooling systems—verifying EG concentration prior to winter service
- Commissioning and seasonal inspection of hydronic heating/cooling circuits in commercial buildings and district energy networks
- Quality control during batch preparation of custom-mixed antifreeze solutions for solar thermal collectors and geothermal heat pumps
- Field validation of freeze protection in chilled water systems, ice rinks, and industrial process coolants
- Educational use in mechanical engineering and HVAC technology curricula for demonstrating colligative property relationships
FAQ
Can the PAL-91S measure propylene glycol-based antifreeze?
No. The optical calibration is specific to ethylene glycol–water systems. Propylene glycol exhibits different refractive index vs. concentration behavior and will yield inaccurate results.
Does the instrument require periodic recalibration?
Factory calibration is stable for the instrument’s service life under normal handling. Users should verify accuracy before each shift using certified reference standards (e.g., 0% and 50% EG standards, available from ATAGO as optional accessories).
Is the PAL-91S suitable for measuring used or contaminated coolant?
Only if contamination is limited to dissolved solids <1% w/w and free of oil, glycol degradation products, or suspended particles. Turbid or oily samples must be centrifuged or filtered prior to measurement to avoid prism fouling and optical interference.
What does the ±0.4% accuracy specification refer to?
It denotes the maximum permissible error in ethylene glycol mass fraction at concentrations between 0.0% and 15.0%, as verified against NIST-traceable reference materials under controlled ATC conditions.
How does automatic temperature compensation (ATC) work?
An integrated thermistor continuously monitors prism surface temperature and applies real-time correction to the refractive index reading using the published temperature coefficient of ethylene glycol solutions—no user input or manual adjustment is needed.
