ISO/TR 23015-2020 pdf free.Fine bubble technology — Measurement technique matrix forthe characterization of fine bubbles.
1.Scope:This document focuses on listing most commonly used preparation and characterization techniques forfine bubbles and their interpretation.The merits and limitations of each of the techniques are outlined.
2.Normative references:There are no normative references in this document.
3.Terms and definitions:No terms and definitions are listed in this document.A number of general particle counting and sizing techniques are available commercially.Some of themare applicable for the characterization of fine bubble dispersions and ultrafine bubble dispersions.Suchdispersions may be in liquid of any kind.Some liquids may not be transparent (e.g. printer ink) or stable (e.g. flammable fuel). This document refers to a selection of commercially available techniques andevaluates their applicability and their limitations.
5.2 Comparison of size and concentration indices from different sources
Consideration should be given when different techniques are being compared, that each techniquemeasures a different physical property of the sample. In deriving size and/or concentration indicesfrom different techniques, it should be anticipated that results will demonstrate differences in valuebut they will likely show trend and/or correlate.
Care should be taken when comparing size and concentration indices.Even if the same technique is used,the method from example two laser diffraction machines will need to be checked to verify parameterssuch as measurement time, analysis models and pump rate.Table 1 provides a quick reference for thetypical size and concentration indices of different techniques in the measurement of bubbles.
6Characterization techniques
This clause deals with individual techniques and how they are applied to characterizing fine bubblesamples.Most samples are assumed to be in a transparent liquid, but some reference to opaque samplesmay be found for techniques that allow their treatment.Dynamic light scattering (DLS]) is also known as photon correlation spectroscopy (PCS). It measuresthe hydrodynamic particle size by measuring the Brownian motion of the fine bubbles in a sample.The technique uses a laser which is passed through a sample and the light scattering measured ona detector. The detector[s) could be at a variety of angles. The intensity of light is measured over arapid timescale. The change in scattering intensity over time as particles diffuse in and out of themeasurement zone is related to their size, small particles diffuse rapidly and large particles slowly.Thetranslational diffusion coefficient is measured which can be turned into the hydrodynamic diameter bythe Stokes Einstein equation [see ISO 22412:2017,Formula (A.5)].This intensity change is expressed as a correlation function which examines the signal change over time.From this information on the size and polydispersity of the sample can be obtained. A size distributionis derived by applying an appropriate algorithm to the correlation function. lt is an intensity-basedtechnique.ISO/TR 23015 pdf download.