OFITE Model 900 Automated Digital Viscometer
| Brand | OFITE |
|---|---|
| Origin | USA |
| Model | 130-76-1-C |
| Instrument Type | High-Temperature Rotational Viscometer |
| Viscosity Range | 0.5–500,000,000 mPa·s |
| Fixed Speeds | 12 (600, 300, 200, 100, 60, 30, 20, 10, 6, 3, 2, 1 rpm) |
| Variable Speed Range | 0.006–1000 rpm |
| Speed Accuracy | ±0.001 rpm |
| Shear Rate Range | 0.01–1700 s⁻¹ |
| Heating Jacket | Stainless Steel, 150 W, Max Temp: 88 °C |
| Power Supply | 97–250 VAC, 200 W, 50/60 Hz |
| Dimensions | 44 × 38 × 24 cm |
| Weight | 8.6 kg |
| Interface | RS-232 (DB-9), Windows 2000 or later, min. 1024×768 resolution |
Overview
The OFITE Model 900 Automated Digital Viscometer is a precision-engineered coaxial cylinder (Couette-type) rotational viscometer designed for rigorous rheological characterization of drilling fluids, cement slurries, and other non-Newtonian industrial suspensions under controlled thermal conditions. Based on the fundamental principle of measuring torque required to rotate an inner cylinder within a stationary outer cylinder at defined angular velocities, the instrument delivers high reproducibility in shear stress and shear rate quantification across an exceptionally wide dynamic range—from ultra-low shear rates (0.01 s⁻¹) up to 1700 s⁻¹. Its patented motor control architecture enables continuous operation during speed transitions—eliminating mechanical dwell time—and supports both standardized API RP 13B-1 (for drilling muds) and ASTM C305 (for hydraulic cements) compliance workflows without manual recalibration. The integrated 150 W stainless-steel heating jacket provides stable thermal conditioning up to 88 °C, making it suitable for downhole simulation and high-temperature fluid stability assessment.
Key Features
- True Couette geometry with concentric cylindrical measurement system ensuring laminar flow fidelity and minimal wall-slip error
- Patented step-motor drive delivering ±0.001 rpm speed accuracy and seamless transition between fixed and user-defined shear rates (0.006–1000 rpm)
- One-touch API mode selection (MUD/CEM) for automated calculation of Plastic Viscosity (PV), Yield Point (YP), and gel strength per API RP 13B-1 and ASTM C305
- KlikLock™ magnetic coupling suspension system (U.S. Patent No. 8,763,776) enabling tool-free rotor exchange in under 15 seconds
- Onboard digital keypad with dedicated function keys for rapid access to standard speeds (600/300 rpm), manual entry of custom shear rates, and real-time display of calculated rheological parameters
- RS-232 serial interface compatible with OFITE’s ORCADATM software for synchronized multi-instrument control, audit-trail logging, and GLP-compliant data export
Sample Compatibility & Compliance
The Model 900 accommodates a broad spectrum of sample types—including water-based muds (WBM), oil-based muds (OBM), synthetic-based muds (SBM), cement slurries, bentonite dispersions, polymer solutions, and heavy brines—without requiring geometry modification. Its temperature-stable measurement chamber and low-shear capability support evaluation of thixotropic recovery, static gel development, and yield behavior critical to wellbore stability modeling. The instrument meets functional requirements of API RP 13B-1 (2022), ASTM D1092, ISO 3219, and USP for rotational viscosity testing. When operated with ORCADATM software under validated configurations, it satisfies FDA 21 CFR Part 11 electronic record and signature requirements for regulated QC/QA environments.
Software & Data Management
ORCADATM software serves as the central data acquisition and analysis platform for the Model 900. It supports concurrent operation of multiple viscometers via daisy-chained RS-232 connections and records timestamped torque, speed, temperature, and calculated parameters (PV, YP, τ₀, n, K) with full metadata tagging. All raw data files are stored in encrypted binary format with SHA-256 checksum integrity verification. The software includes built-in report templates compliant with API, ASTM, and internal laboratory SOPs; exports to CSV, PDF, and XML formats; and maintains immutable audit trails for all user actions—including parameter edits, calibration events, and data deletions—required for GMP/GLP audits. Language modules include English, Simplified Chinese, and Russian.
Applications
- Routine quality control of drilling fluid formulations in field laboratories and service company hubs
- Development and optimization of low-solids, high-performance mud systems for extended-reach and HPHT wells
- Cement slurry rheology profiling for centralization efficiency and displacement modeling
- Thermal stability assessment of viscosifiers and fluid loss additives across operational temperature windows
- Research into shear-thinning behavior, yield stress hysteresis, and structural breakdown kinetics of complex colloidal suspensions
- Calibration traceability support for ISO/IEC 17025-accredited testing laboratories
FAQ
What standards does the Model 900 comply with for drilling fluid testing?
It supports full implementation of API RP 13B-1 (2022) for plastic viscosity, yield point, and gel strength determination.
Can the instrument operate without a computer connection?
Yes—the standalone mode enables complete API-compliant testing using only the front-panel keypad and LCD display.
Is the heating jacket programmable for ramp-and-hold temperature profiles?
No—it provides constant-power resistive heating with manual thermostat adjustment; precise thermal ramping requires external PID controllers.
What maintenance is required for long-term accuracy?
Annual verification of speed calibration using certified tachometer and periodic cleaning of the bob/cup assembly with solvent-rinsed lint-free wipes.
Does ORCADATM support automated report generation for regulatory submissions?
Yes—preconfigured templates generate audit-ready reports with embedded electronic signatures, revision history, and instrument calibration status.
