StoneDDI Stone Calibrator

Performing foam stability and foaming tendencies of lubricant oils involves a tightly controlled flow of gas -- typically air -- being dispersed into a measured volume of the test liquid at predetermined conditions of time, air flows and temperatures. This is in accordance with standardized methods such as ASTM D892, D6082 and IP 146. The creation of foam can be associated with the nature of the oil in question and the efficiency in which the diffuser funnels air into the formulations being tested. A faulty automated diffuser impacts the quality of the analysis, therefore impacting the overall performance of the tests.

The determination of the foaming characteristics of lubricating oils at 24C, 93.5C and 150 C, empirically rate the foaming tendency and the stability of the foam that might be formed in normal operations. The system is also capable of performing this at any temperature or conditions with equal ease. In both methods, FoamDDI eliminates any confusion that may arise when interpreting the procedure results, and guarantees compliance with test temperature requirements and exact definitions of kinetic and static foam performing the measurement at the correct times. These test methods require that the condition of the diffuser used has pore sizes and permeabilities. Calibration of diffusers to verify maximum pore size and permeability have been found to be critical factors for the tests. It is recommended that these diffusers be calibrated when new and periodically checked after each test.

The Stone Digital Detection Imaging Apparatus (StoneDDI) easily provides unbiased and reliable measurements of pore size distribution and flow rates of plastic, ceramic, and metallic diffusers of different shapes and dimensions. StoneDDI is the ultimate system for sample conditioning and testing. It is equipped with a high-resolution CCD camera and reader unit that possesses state-of-the-art optics. Together with the VISAYA FoamDDI algorithm, StoneDDI accurately determines pore diameters and size distribution to unambiguously and reproducibly calibrate them. For pore size verification, StoneDDI directs air to the diffuser that is immersed in water in a glass measuring cylinder. The high precision and accuracy of the calibration is guaranteed by the precise control of air flows and procedural steps, adhering to the standard methods, with minimal operator manipulation. This eliminates the critical timing involved in the manual assessment and characterizes the calibrations by high repeatability and reproducibility. The automatic system produces simultaneously plots, pictures and videos allowing to visually and integrally characterize your analyzers.

The stone calibration device automatically measures the pressure in Pa and converts it in mm H2O. The diameter is calculated by the equation D = 8930/(PmmH2O-80) for metallic diffusers utilizing isopropanol as the diffuser medium. The permeability is considered to be equal to the flow rate measured at 2.45 kPa of pressure.

The flow meter calibration can be visually expressed as the reading in mm vs. the flows measured at center of flow.

Automated diffuser stone calibrator for use with FoamDDI.
Used for certification of pore and permeability as required in ASTM D892 & D6082.