Longteng ESJ120-4B Precision Analytical Balance

Overview

The Longteng ESJ120-4B Precision Analytical Balance is a high-reproducibility laboratory balance engineered for quantitative mass measurement in regulated and research-grade environments. It operates on the principle of electromagnetic force compensation (EMFC), where sample weight is counterbalanced by a precisely controlled electromagnetic current—measured and converted into digital mass output with traceable linearity. Designed to meet the operational requirements of quality control laboratories, pharmaceutical R&D, academic chemistry departments, and materials testing facilities, the ESJ120-4B delivers 0.1 mg readability across its full 120 g capacity range. Its robust mechanical architecture—including a rear-mounted EMFC sensor and triple-door draft shield—minimizes air-current interference and thermal drift, ensuring stable readings under variable ambient conditions. The balance complies with foundational metrological practices aligned with ISO 9001 and supports workflows consistent with GLP and GMP documentation frameworks when integrated with validated data management systems.

Key Features

• Rear-mounted high-stability electromagnetic force compensation sensor for enhanced long-term calibration retention and reduced mechanical hysteresis
• Triple-door acrylic draft shield with wide access aperture (Φ90 mm stainless steel pan) enabling safe handling of volumetric flasks, crucibles, and multi-component sample vessels
• Backlit LCD display with adjustable brightness—optimized for both low-light analytical suites and brightly lit production labs
• Automatic external calibration routine using supplied stainless steel calibration weights (Class M2 or better), compliant with internal SOPs requiring documented calibration events
• Real-time overload/underload detection with audible and visual alerts to prevent sensor damage and ensure measurement integrity
• Integrated temperature compensation algorithm that dynamically adjusts zero-point stability across typical lab temperature ranges (10–30 °C)
• Full-range tare functionality, cumulative weighing, net/gross switching, and bidirectional subtraction for multi-step formulation protocols

Sample Compatibility & Compliance

The ESJ120-4B accommodates diverse sample forms including powders, granules, liquids in tared containers, filter papers, and small metallic specimens—provided they remain within the 120 g limit and do not exceed the 90 mm pan diameter. Its design conforms to general-purpose analytical balance specifications outlined in USP , ASTM E898-22 (Standard Guide for Selection and Use of Laboratory Balances), and ISO 17025 clause 6.4.2 regarding equipment suitability. While the unit itself is not CE-marked or FDA 510(k)-cleared, it is routinely deployed in non-regulated QC settings and as a secondary verification tool in ISO 17025-accredited laboratories—subject to user-performed verification per internal validation protocols. Optional accessories—including density determination kits and below-balance weighing hooks—extend functionality without compromising structural integrity or metrological performance.

Software & Data Management

Equipped with an industry-standard RS232 serial interface, the ESJ120-4B enables direct communication with LIMS platforms, electronic lab notebooks (ELNs), and statistical process control (SPC) software via ASCII-based data streaming. Output format is configurable (e.g., “S” for stable reading trigger, “T” for time-stamped records), supporting automated data capture compliant with ALCOA+ principles (Attributable, Legible, Contemporaneous, Original, Accurate). When paired with validated third-party drivers (e.g., LabX-compatible middleware), the balance supports 21 CFR Part 11-compliant audit trails—including operator ID logging, calibration event timestamps, and parameter change history—provided the host system implements appropriate access controls and electronic signature mechanisms.

Applications

• Pharmaceutical active ingredient (API) dispensing and blend uniformity testing
• Gravimetric preparation of standard solutions (e.g., ICP-MS calibration standards)
• Residue-on-ignition (ROI) and loss-on-drying (LOD) determinations per USP
• Micro-scale catalyst loading in heterogeneous catalysis research
• Educational stoichiometry experiments requiring sub-milligram precision
• Quality assurance of reference materials certified to ISO Guide 35 specifications

FAQ

What calibration standards are required for external calibration?
The ESJ120-4B requires Class M2 or higher stainless steel calibration weights traceable to national metrology institutes (e.g., NIST, PTB, or NIM). Calibration must be performed at ambient temperatures within ±2 °C of the balance’s operating range.
Is internal calibration available on this model?
No—the ESJ120-4B supports external automatic calibration only; no built-in motorized calibration mass is included.
Can the balance be used in a fume hood?
Not recommended due to airflow-induced instability; use only in still-air environments with draft shields fully closed.
Does the RS232 interface support USB conversion?
Yes—standard RS232-to-USB adapters (with FTDI or CH340 chipsets) are compatible, provided driver installation and port configuration align with host software requirements.
What is the warm-up time before achieving specified repeatability?
Minimum 30 minutes after power-on under stable ambient conditions (20–25 °C, <60% RH); longer stabilization may be necessary following large ambient temperature shifts.