KEM CHD-502C Automated Low-Temperature Sample Changer for Oscillating U-Tube Density Meters

Overview

The KEM CHD-502C is an automated low-temperature sample handling system engineered exclusively for integration with KEM’s oscillating U-tube digital density meters—including the DA-6XX series (e.g., DA-650, DA-645, DA-640). It operates on the fundamental principle of measuring the resonant frequency shift of a precisely machined U-shaped glass tube filled with sample fluid; this shift correlates directly to the sample’s mass density via calibrated physical constants. The CHD-502C extends this high-precision measurement capability into unattended, temperature-controlled, multi-sample workflows—particularly critical for applications requiring thermal stability at sub-ambient conditions (down to 4 °C) and rigorous repeatability across large sample sets. Its architecture eliminates manual pipetting, rinsing, and drying steps, thereby minimizing operator-induced variability and contamination risk while preserving metrological integrity throughout sequential analysis.

Key Features

• Fully automated sample introduction, dispensing, solvent rinse, air purge drying, and waste management—all under coordinated control of the host densimeter.
• 30-position sample carousel accommodating standard 20 mL glass vials, enabling overnight or extended unattended operation without intervention.
• Integrated dual-mode fluid handling system: vacuum-assisted aspiration for viscous or volatile liquids, followed by positive-pressure expulsion for complete sample recovery into original vials—supporting traceability and regulatory compliance (e.g., GLP sample accountability).
• Designed for seamless interoperability with KEM DA-series densimeters; all sequence logic, error handling, and calibration verification are managed through the instrument’s native firmware—no third-party software layer required.
• Low-power benchtop footprint (24 kg, <40 W) with robust mechanical construction suitable for ISO 17025-accredited laboratories and regulated QC environments.

Sample Compatibility & Compliance

The CHD-502C supports a broad range of liquid samples—from aqueous solutions and organic solvents to high-viscosity oils, polymer melts (up to 50,000 mPa·s), and cryogenic formulations. Its sealed fluid path minimizes evaporation and oxidation during transfer, especially critical for low-boiling-point or air-sensitive materials. Temperature uniformity is maintained via external recirculating chillers compatible with ASTM D4052, ISO 12185, and USP density determination protocols. All wetted components comply with USP Class VI biocompatibility standards; system logs include timestamped audit trails for sample ID, temperature setpoint, rinse cycle count, and density result—fully aligned with FDA 21 CFR Part 11 requirements when used with validated DA-series host instruments.

Software & Data Management

Operation is governed by KEM’s proprietary Density Manager software (v4.0+), which provides full method scripting, sequence scheduling, real-time status monitoring, and automatic metadata embedding (e.g., ambient lab temperature, bath stability, rinse solvent lot number). Raw oscillation period data, temperature-corrected density values, and statistical summaries (mean, SD, RSD, n) are exported in CSV, PDF, or LIMS-compatible XML formats. Built-in validation tools support IQ/OQ documentation per GAMP 5 guidelines; electronic signatures and role-based access control are configurable for multi-user GxP environments.

Applications

• Pharmaceutical excipient and API density profiling under controlled cold-chain conditions (e.g., refrigerated formulation stability studies).
• Quality control of petrochemical fractions, biofuels, and lubricants across wide viscosity and volatility ranges.
• Academic and industrial research in colloid science, electrolyte solutions, and ionic liquid characterization where thermal hysteresis must be minimized.
• Food & beverage QC for sugar concentration (Brix), alcohol content, and syrup density—validated against AOAC 982.22 and ISO 2173 methodologies.
• Environmental testing of contaminated groundwater or leachates where low-temperature preservation prevents analyte degradation prior to analysis.

FAQ

Can the CHD-502C operate independently without a KEM densimeter?
No—it is not a standalone instrument. It functions solely as a peripheral module and requires active communication with a compatible KEM DA-series densimeter (DA-640/645/650) for command execution and data acquisition.
Is the system compatible with non-KEM density meters?
Not natively. While electrical I/O ports exist, KEM does not publish protocol specifications for third-party integration; no OEM-certified drivers or SDKs are available.
How is temperature stability ensured during low-temperature operation?
The CHD-502C itself lacks internal thermoregulation. It relies entirely on an externally connected, programmable circulating chiller (e.g., Julabo F25 HL) maintaining bath temperature between 4 °C and ambient; thermal equilibration time is verified per ISO 12185 Annex B.
What maintenance intervals are recommended for the vacuum-pressure pump?
KEM specifies 12-month preventive servicing—including diaphragm inspection, valve cleaning, and lubricant replacement—under typical usage (≤1000 cycles/month); service records are stored in the instrument’s internal memory with automatic alert triggers.
Does the system support custom rinse protocols for aggressive solvents?
Yes. Up to five user-defined rinse sequences (solvent type, volume, dwell time, purge duration) can be programmed and recalled per sample group, ensuring compatibility with chlorinated, fluorinated, or high-polarity cleaning agents.