ASTM E2872-14 (2024) PDF

Full title and description

St ASTM E2872-14 (2024) — Standard Guide for Determining Cross-Section Averaged Characteristics of a Spray Using Laser‑Diffraction Instruments in a Wind Tunnel Apparatus. This guide describes procedures for using laser‑diffraction (LD) instruments to obtain an averaged droplet‑size distribution representative of the flux of liquid droplets produced by a spray generation device operating in a controlled gas co‑flow (wind tunnel) environment.

Abstract

This guide provides recommended test methods and data‑processing practices for estimating a cross‑section averaged droplet‑size distribution from spatial LD measurements of sprays in high‑speed gas co‑flow. It addresses instrument placement (non‑intrusive sampling), traversing multiple chords across the spray cross section to obtain representative averages, appropriate optical size ranges, and the use of Mie or Fraunhofer scattering models and instrument data processing consistent with related ASTM practices and test methods. The procedure is intended primarily for evaluation of nozzles, atomizers, and other spray generation devices.

General information

• Status: Published.
• Publication date: January 31, 2024 (current edition approved February 1, 2024; effective date February 1, 2024).
• Publisher: ASTM International.
• ICS / categories: 55.130 — Aerosol containers / particle & spray characterization.
• Edition / version: Designation E2872−14 (reapproved 2024).
• Number of pages: 9 pages.

Scope

The guide defines a test procedure for applying laser‑diffraction methods to estimate an average droplet‑size distribution that characterizes the flux of liquid droplets produced by a specified spray generation device under specified gas co‑flow conditions. It is limited to artificially generated sprays with high‑speed co‑flow, with droplet diameters typically in the range of about 1 µm to 2000 µm, and to sprays contained within volumes from a few cubic centimetres up to about a cubic metre. Multiple‑chord (spatially averaged) sampling is required for non‑uniform sprays to obtain a single distribution representative of the entire spray cross section.

Key topics and requirements

• Use of laser‑diffraction (LD) instrumentation to derive droplet‑size distributions and conversion of LD scattering intensities into size parameters consistent with Practice E799 and Test Method E1260.
• Requirement for non‑intrusive instrument mounting so the LD system does not disturb spray production or co‑flow.
• Multiple‑chord traverses across the spray cross section to produce a cross‑section averaged (flux‑equivalent) distribution when droplet velocity conditions permit equivalence between spatial and flux samples.
• Recommended droplet size reporting range and matching of LD optic size range to the spray (practical range ~1 µm to 2000 µm).
• Use of scattering theory: Mie theory (requires refractive index knowledge) or Fraunhofer approximation (no refractive index required) with guidance on applicability.
• Wind‑tunnel requirements: uniform low‑turbulence co‑flow, sufficient test section to enclose plume and wakes, and measurement of gas phase velocity uniformity/steadiness.
• Guidance on optical access, working distance, and avoiding droplet impacts on tunnel walls; attention to safety and hazardous materials where applicable.

Typical use and users

Primary users include spray and nozzle manufacturers, agricultural and forestry spray researchers, aerosol instrumentation developers, test laboratories performing spray characterization, and regulatory or product development groups that require validated droplet‑size distributions for performance, drift, or coverage assessments. The guide is typically used in wind‑tunnel test setups to calibrate sprayers, compare nozzle performance, or characterize unknown sprays under controlled co‑flow conditions.

Related standards

Normative and related references highlighted by this guide include Practice E799 (data analysis for LD), Test Method E1260 (LD test methods for liquid drop size), ISO 13320 (particle size analysis — laser diffraction methods), and Terminology E1620. The guide sits under ASTM Committee E29 (Particle and Spray Characterization) and Subcommittee E29.02 (Non‑Sieving Methods).

Keywords

laser diffraction; droplet size distribution; spray characterization; wind tunnel; co‑flow; nozzle testing; atomizer performance; Mie scattering; Fraunhofer; flux‑sensitive sample; spatial averaging; ASTM E2872.

FAQ

Q: What is this standard?

A: ASTM E2872‑14 (reapproved 2024) is a guide for determining cross‑section averaged droplet‑size characteristics of sprays using laser‑diffraction instruments in a wind tunnel (gas co‑flow) apparatus.

Q: What does it cover?

A: It covers recommended procedures for instrument placement and sampling (multiple‑chord traverses), data processing, applicable droplet size ranges (≈1 µm–2000 µm), selection of scattering theory (Mie or Fraunhofer), and wind‑tunnel test conditions needed to obtain a representative, flux‑equivalent droplet‑size distribution.

Q: Who typically uses it?

A: Spray and nozzle manufacturers, agricultural/forestry spray researchers, aerosol instrument developers, testing laboratories, and regulatory and product development teams that need standardized droplet‑size characterization.

Q: Is it current or superseded?

A: Current. The designation E2872‑14 was reapproved and the edition approved February 1, 2024 (publication/effective around January 31 – February 1, 2024). It replaces the previous reapproval edition (E2872‑14(2019)).

Q: Is it part of a series?

A: It is part of ASTM Committee E29's body of standards on particle and spray characterization and specifically produced by Subcommittee E29.02 (Non‑Sieving Methods). It is related to other E29 standards for particle size and spray measurement (for example E799, E1260, E1617 and others in the E29 suite).

Q: What are the key keywords?

A: Laser diffraction, droplet size distribution, spray, wind tunnel, co‑flow, nozzle testing, Mie theory, Fraunhofer approximation, flux‑sensitive sample.