Leici DDB-305A Portable Conductivity Meter

Overview

The Leici DDB-305A Portable Conductivity Meter is a laboratory-grade electrochemical instrument engineered for precise, field-deployable measurement of electrical conductivity, total dissolved solids (TDS), and temperature in aqueous solutions. Based on the fundamental principle of conductometric analysis—measuring the solution’s ability to carry electric current via ion mobility—the DDB-305A employs a two-electrode AC conductivity cell to minimize polarization effects and electrode fouling. Its auto-ranging circuitry dynamically selects optimal excitation frequencies (typically 1 kHz or 10 kHz) to ensure stable readings across the full 0.00 μS/cm to 200 mS/cm span, eliminating manual range switching and reducing operator error. Designed for routine QC/QA workflows in environmental monitoring, pharmaceutical water testing, academic teaching labs, and industrial process support, the instrument meets the functional requirements of ISO 7888 (water conductivity determination) and aligns with ASTM D1125 guidelines for conductivity and TDS correlation.

Key Features

• High-contrast LCD display with adjustable backlight for low-light or outdoor use
• IP65-rated enclosure providing dust-tight protection and resistance to low-pressure water jets—suitable for humid lab environments and controlled field sampling
• Integrated smart electrode detection: automatically recognizes and configures the supplied composite conductivity electrode (cell constant K = 1.0 cm⁻¹)
• Dual measurement modes: equilibrium mode (with intelligent endpoint detection) and continuous real-time logging—enabling both compliance-driven snapshot measurements and kinetic trend analysis
• Automatic temperature compensation (ATC) using integrated NTC thermistor; supports manual offset adjustment for non-standard calibration conditions
• Pre-programmed recognition of four Chinese national standard (GB) conductivity reference solutions (e.g., 1413 μS/cm, 12.88 mS/cm), enabling rapid one-point calibration per GB/T 6682 and JJG 376
• Auto-frequency switching ensures optimal signal-to-noise ratio across ultra-low (μS/cm) and high-conductivity (mS/cm) regimes without electrode reconfiguration
• Built-in rechargeable lithium-ion battery (≥12 hours typical runtime); USB-C compatible charging from PC or portable power banks; real-time battery status and low-voltage warning

Sample Compatibility & Compliance

The DDB-305A is validated for use with clean to moderately turbid aqueous samples—including purified water (PW), water-for-injection (WFI) pre-tests, surface water, wastewater effluents, and buffer solutions. It is not intended for highly viscous, suspended-solid-laden, or strongly oxidizing media without prior filtration or dilution. The instrument complies with general safety requirements per IEC 61010-1 (electrical safety for laboratory equipment) and electromagnetic compatibility per IEC 61326-1. While not certified for GMP or FDA 21 CFR Part 11 out-of-the-box, its data integrity features—including timestamped storage of 200 measurement records with parameter metadata (conductivity, TDS, temp, date/time, electrode ID)—support GLP-aligned documentation practices when used with defined SOPs.

Software & Data Management

Measurements are stored internally with full traceability: each record includes conductivity value, TDS equivalent, temperature, measurement mode, calibration status, and timestamp. Data export is performed via USB connection to a host PC using vendor-provided basic utility software (no proprietary cloud platform). The software enables CSV export for integration into LIMS or Excel-based trending tools. Audit trail functionality is limited to manual logbook correlation; for regulated environments requiring electronic signature or change control, external validation and procedural controls must be implemented per organizational quality systems.

Applications

• Verification of deionized and distilled water purity in pharmaceutical manufacturing and biotech labs
• Field-based assessment of river, lake, and groundwater salinity and ionic load
• Educational demonstrations of electrolyte behavior, dissociation constants, and solution conductivity theory
• Monitoring boiler feedwater and cooling tower cycles in industrial maintenance programs
• Supporting USP non-sterile water conductivity testing as part of preliminary screening (note: final release testing requires USP-compliant, calibrated instruments under validated procedures)
• Calibration verification of inline conductivity sensors in pilot-scale process systems

FAQ

Does the DDB-305A support multi-point conductivity calibration?
No—it supports only single-point calibration using recognized GB standard solutions. Multi-point calibration is not implemented in firmware.
Can the instrument measure resistivity directly?
No—resistivity is the reciprocal of conductivity and must be calculated externally using the recorded conductivity value and cell constant.
Is the included electrode suitable for high-temperature measurements up to 110 °C?
Yes, the supplied composite electrode is rated for continuous operation within the full specified temperature range (−5 °C to 110 °C), provided thermal shock is avoided.
What happens if the battery fully discharges during measurement?
The device retains all stored data and calibration settings in non-volatile memory; no data loss occurs upon power interruption.
Is firmware upgrade capability available?
Firmware updates are provided by Leici via authorized service centers; no user-accessible OTA or USB-based update interface is included in the DDB-305A design.