PULUODY PLD-0221A Liquefied Petroleum Gas (LPG) Density Analyzer

Overview

The PULUODY PLD-0221A Liquefied Petroleum Gas (LPG) Density Analyzer is a precision laboratory instrument engineered for the gravimetric determination of density and relative density of liquefied petroleum gas in accordance with SH/T 0221—“Test Method for Density of Liquefied Petroleum Gases (LPG)”. This standard specifies the use of a calibrated metal hydrometer (specific gravity bottle or pycnometer-based measurement system) under strictly controlled temperature conditions to ensure traceable, repeatable results. The analyzer integrates a closed-loop refrigeration system, high-stability thermal chamber, and digital PID temperature controller to maintain sample equilibrium at defined test temperatures—primarily 15 °C and 20 °C—per industry-standard calibration protocols. Its design adheres to fundamental metrological principles for liquid-phase density measurement of volatile hydrocarbon mixtures, where thermal equilibration, vapor pressure management, and minimal operator intervention are critical to data integrity.

Key Features

• Integrated hermetic refrigeration unit enabling precise temperature regulation from 15 °C to 20 °C with ±0.2 °C stability over extended test cycles
• Digital PID temperature controller with auto-tuning capability, providing intuitive setpoint adjustment and real-time display of chamber temperature
• Internal LED illumination system for clear visual inspection of sample meniscus and hydrometer immersion during manual density reading
• Robust stainless-steel thermal chamber housing with insulated enclosure, minimizing ambient thermal drift and supporting operation across diverse laboratory environments
• Compliance-ready architecture: designed to support documented temperature verification, calibration log retention, and procedural adherence required under ISO/IEC 17025-accredited testing workflows

Sample Compatibility & Compliance

The PLD-0221A is validated for use with commercial-grade LPG blends—including propane, butane, and their mixtures—as specified in SH/T 0221. It accommodates standard ASTM D1657–22 and ISO 3993:2021 sample handling practices when adapted with appropriate high-pressure sampling cylinders and transfer manifolds. While the instrument itself does not perform direct pressure compensation, its thermal control system ensures samples are brought to equilibrium at reference temperatures prior to density assessment using calibrated glass hydrometers or oscillating U-tube densitometers (when interfaced externally). The unit supports GLP-compliant operation through stable thermal performance, reproducible conditioning cycles, and compatibility with third-party calibration certificates traceable to NIM (National Institute of Metrology, China) or equivalent national metrology institutes.

Software & Data Management

The PLD-0221A operates as a standalone hardware platform with embedded microcontroller-based temperature regulation; no proprietary software is bundled. However, its digital temperature interface provides RS-485 or optional analog 4–20 mA output for integration into laboratory information management systems (LIMS) or SCADA environments. Users may record chamber temperature logs manually or via external data acquisition modules compliant with FDA 21 CFR Part 11 requirements—provided audit trail functionality, electronic signature support, and secure user access controls are implemented at the host system level. Calibration records, maintenance logs, and temperature validation reports should be retained per ISO/IEC 17025 clause 7.7 and internal quality procedures.

Applications

• Quality control testing of LPG feedstock and finished products in refining and distribution facilities
• Verification of blend composition consistency (e.g., propane/butane ratio) via density correlation models
• Supporting custody transfer calculations where density-derived mass flow corrections are applied
• Method validation and interlaboratory comparison studies aligned with SH/T 0221 and related regional standards
• Training and method development in petrochemical analytical laboratories requiring hands-on exposure to standardized LPG physical property measurement

FAQ

Does the PLD-0221A include an integrated hydrometer or density sensor?
No. It is a temperature-controlled conditioning platform designed to prepare and stabilize LPG samples prior to density measurement using externally calibrated hydrometers or digital densitometers.
Can this instrument operate continuously at 15 °C in ambient environments above 30 °C?
Yes—the built-in compressor-based cooling system is rated for sustained operation within the specified temperature range under typical laboratory ambient conditions (up to 35 °C, ≤70% RH).
Is the unit compatible with international calibration standards such as ASTM D1657?
While SH/T 0221 is its primary design basis, the thermal performance and dimensional specifications align with the environmental control requirements of ASTM D1657–22 for LPG density testing, provided proper sample handling accessories are employed.
What maintenance is required for long-term reliability?
Routine checks include refrigerant pressure verification, condenser coil cleaning every six months, and annual calibration of the embedded PT100 temperature sensor against a NIST-traceable reference thermometer.
Does PULUODY provide installation qualification (IQ) or operational qualification (OQ) documentation?
Upon request, PULUODY supplies factory-verified temperature uniformity maps and calibration certificates for the control sensor; full IQ/OQ protocol development must be performed by the end-user’s qualified validation team in accordance with local regulatory expectations.