PULUODY DMA-135D Portable Digital Density Meter

Overview

The PULUODY DMA-135D Portable Digital Density Meter is an engineered precision instrument designed for rapid, field-deployable measurement of liquid density, relative density (specific gravity), and API gravity across diverse industrial and laboratory environments. It operates on the oscillating U-tube principle—a well-established physical method where the resonant frequency of a filled, vibrating U-shaped glass tube correlates directly with the mass of the sample, enabling highly reproducible density determination without reliance on temperature-controlled bath immersion or manual hydrometer readings. This metrological foundation ensures traceability to international standards and supports routine quality control in dynamic operational settings—from refinery offsite sampling to lubricant formulation labs and pharmaceutical manufacturing support.

Key Features

• True portable architecture: battery-powered operation with integrated rechargeable Li-ion pack, enabling >8 hours continuous use without external power
• Integrated Peltier temperature control system maintaining sample temperature stability within ±0.02 °C during measurement—critical for viscosity-sensitive fluids such as lubricants and transformer oils
• Automated air/liquid purge sequence minimizing carryover and cross-contamination between samples
• High-resolution 4.3-inch capacitive touchscreen interface with multilingual UI (English, Spanish, Chinese) and intuitive workflow navigation
• Robust aluminum-magnesium alloy housing rated IP65 for dust and water resistance—suitable for workshop, tank farm, and marine deck environments
• Real-time density output with automatic temperature compensation referenced to 15 °C, 20 °C, or 60 °F per user selection

Sample Compatibility & Compliance

The DMA-135D accommodates a broad spectrum of Newtonian and mildly non-Newtonian liquids, including but not limited to: mineral and synthetic lubricating oils, hydraulic fluids, insulating oils (IEC 60296 compliant), cutting and washing solvents, crude oil fractions, biodiesel blends (B5–B20), aqueous cleaning agents, electroplating baths, fluxes, food-grade vegetable oils, alcoholic beverages, and pharmaceutical excipients. Its measurement range spans 0.600–3.000 g/cm³ with resolution of 0.0001 g/cm³, supporting full compliance with GB/T 29617–2013 (Digital Density Meter Method for Liquids), ASTM D4052–11 (primary standard for refinery QC), ISO 12185:1996 (oscillating U-tube method for crude and products), and IP 559–2008 (middle distillate fuels). All calibration protocols follow GLP-aligned procedures, with optional NIST-traceable certificate documentation available upon request.

Software & Data Management

Data integrity and audit readiness are ensured through embedded firmware supporting 21 CFR Part 11-compliant user access control, electronic signature capability, and immutable measurement log storage (≥10,000 records with timestamp, operator ID, temperature, density, and pass/fail status). Optional PC software (PULUODY DensityLink v3.2) enables CSV/Excel export, trend charting, statistical process control (SPC) reporting, and integration into LIMS environments via TCP/IP or USB-C. Firmware updates are delivered via signed OTA packages, preserving cryptographic verification of code authenticity and version lineage.

Applications

• Petroleum sector: On-site verification of crude assay batches, blending stock density, fuel specification checks (e.g., diesel EN 590, jet fuel ASTM D1655)
• Lubricant manufacturing: Viscosity index improver concentration monitoring, base oil classification, additive package homogeneity assessment
• Pharmaceutical QA/QC: Ethanol/water mixture verification for solvent recovery systems, density-based concentration checks of syrups and injectables per USP
• Food & beverage: Alcohol content estimation in spirits (via density–alcohol tables), plant oil adulteration screening, sugar syrup Brix correlation
• Electronics manufacturing: Flux density consistency validation, PCB cleaning solution concentration tracking, plating bath metal ion loading estimation
• Academic & research: Teaching vibrational metrology principles, student-led fluid property characterization projects, environmental water sample salinity proxy analysis

FAQ

What is the minimum sample volume required for a valid measurement?
Typically 1.5 mL for full tube fill; however, low-volume mode permits reliable results with ≥0.8 mL using proprietary flow optimization algorithms.
Does the instrument require periodic recalibration with certified reference materials?
Yes—annual recalibration is recommended using NIST SRM 1827 (water) and SRM 1828 (benzene), or equivalent national metrology institute standards; factory calibration certificates include uncertainty budgets per ISO/IEC 17025.
Can the DMA-135D measure samples containing suspended solids or entrained air?
No—samples must be homogeneous, bubble-free, and particle-free (<5 µm filtration recommended); presence of particulates or gas bubbles introduces systematic error due to altered effective mass distribution in the U-tube.
Is the device compatible with hazardous area classifications (e.g., ATEX or IECEx)?
Not intrinsically safe by default; however, explosion-proof enclosures (Zone 2 / Class I Div 2) are available as OEM-configured variants upon formal inquiry.
How does temperature stabilization affect measurement repeatability?
Without active thermal control, density drift exceeds ±0.0005 g/cm³ per 0.1 °C change in ambient; the built-in Peltier system reduces this to ±0.0001 g/cm³ over typical operating ranges (10–40 °C), meeting ASTM D4052 repeatability requirements (≤0.0002 g/cm³).