Truelab NDJ-8S Digital Rotational Viscometer

Overview

The Truelab NDJ-8S Digital Rotational Viscometer is a benchtop instrument engineered for precision measurement of dynamic viscosity in Newtonian and mildly non-Newtonian fluids across research, quality control, and production environments. It operates on the principle of rotational viscometry—applying controlled torque to a rotating spindle immersed in the sample, where resistance to rotation is directly proportional to fluid viscosity. The NDJ-8S employs a microprocessor-controlled synchronous motor to maintain precise, stable rotational speeds independent of line voltage fluctuations, ensuring repeatable shear-rate application at 6, 12, 30, and 60 rpm. Its modular spindle system (LV#1–#4) enables broad dynamic range coverage—from low-viscosity solvents (0.1 mPa·s) to highly viscous pastes and gels (up to 2,000,000 mPa·s)—when combined with appropriate speed/spindle combinations. Unlike capillary or falling-ball instruments, the NDJ-8S delivers direct kinematic-to-dynamic viscosity conversion without empirical calibration drift, making it suitable for routine QC testing where traceability and method consistency are critical.

Key Features

• Bilingual digital LCD display (English/Chinese) with real-time viscosity readout, speed indication, and spindle identification
• Four fixed-speed settings (6/12/30/60 rpm) driven by a regulated AC synchronous motor—immune to mains frequency variation
• Standard LV spindle set (#1–#4) optimized for low-to-medium viscosity ranges; compatible with optional RV/HA/HB spindles for extended range
• Automatic zero calibration and torque auto-ranging reduce operator dependency and minimize setup errors
• Robust aluminum alloy chassis with anti-vibration base design for stable measurements on standard lab benches
• No integrated temperature control; designed for use with external thermostatic baths (e.g., circulating chillers or water jackets) per ISO 3219 requirements

Sample Compatibility & Compliance

The NDJ-8S is validated for homogeneous, particulate-free liquids exhibiting laminar flow under applied shear. Typical applications include solvent-based coatings, edible oils, pharmaceutical suspensions, adhesives, and polymer solutions. It is not intended for highly thixotropic, yield-stress, or particle-laden slurries requiring controlled shear ramping or yield point determination. The instrument conforms to fundamental mechanical and electrical safety standards (GB 4793.1–2007, equivalent to IEC 61010-1). While the NDJ-8S itself does not provide temperature regulation, its spindle geometry and torque sensor alignment meet dimensional tolerances specified in ISO 2555 for rotational viscometers. When operated within an externally controlled thermal environment (±0.1 °C stability), data generated supports compliance with ASTM D2196 (paints and related materials) and USP (viscosity of semisolid dosage forms) when validated per laboratory SOPs.

Software & Data Management

The NDJ-8S operates as a standalone instrument with no native PC connectivity or proprietary software. All measurements are displayed and retained locally on the LCD screen only—no internal memory, USB export, or audit trail functionality is included. For laboratories requiring electronic recordkeeping, integration is achieved via manual transcription or third-party analog/digital signal capture (e.g., RS-232 adapters with custom LabVIEW or Python scripts). To support GLP/GMP workflows, users must implement procedural controls—including daily verification with certified reference oils (e.g., Cannon-Fenske N-series), documented calibration logs, and operator training records—as the device lacks FDA 21 CFR Part 11-compliant electronic signature or data integrity features.

Applications

• QC release testing of industrial lubricants and transformer oils per ASTM D445
• Batch consistency verification of food-grade syrups, dressings, and dairy emulsions
• Stability assessment of topical pharmaceutical gels and ointments during formulation development
• Viscosity grading of architectural paints and coil coatings prior to spray application
• Educational demonstrations of Newtonian behavior, shear-thinning trends, and spindle selection logic

FAQ

Does the NDJ-8S include temperature control?
No. It is a ambient-temperature-only instrument. External temperature regulation (e.g., circulating bath + immersion sleeve) is required for temperature-dependent measurements.
What spindle set is supplied with the NDJ-8S?
The standard configuration includes four low-viscosity (LV) spindles: #1, #2, #3, and #4, each with defined geometry and calibration constants.
Can the NDJ-8S measure non-Newtonian fluids accurately?
It provides single-point apparent viscosity values at discrete shear rates. For full rheological characterization (flow curves, yield stress, thixotropy), a programmable rheometer with variable shear rate control is recommended.
Is calibration certification included?
No factory calibration certificate is provided. Users must perform initial verification using traceable standard oils and maintain in-house calibration records per ISO/IEC 17025 guidelines.
What is the minimum sample volume required?
For LV#1–#4 spindles, a minimum depth of 40 mm and container diameter ≥62 mm are required to satisfy geometry boundary conditions per ISO 3219.