ASTM E1620-97
(Terminology)Standard Terminology Relating to Liquid Particles and Atomization
Standard Terminology Relating to Liquid Particles and Atomization
SCOPE
1.1 The terms covered in this terminology apply to two broad, generic classifications; terms related to characterizing liquid particles and terms relating to the process of atomization.
1.2 Terms in the first class pertain to the structure and condition of individual particles or groups of particles as observed in nature or produced by an atomizing device.
1.3 Terms in the second class are associated with the mechanism and various stages of liquid atomization.
1.4 The following terms have special relevance in the area of spray technology.
General Information
Relations
Standards Content (Sample)
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Designation: E 1620 – 97
Standard Terminology
Relating to Liquid Particles and Atomization
This standard is issued under the fixed designation E 1620; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The transformation of bulk liquid into collections of discrete drops in sprays or mists is required for
many processes including combustion, spray drying, evaporative cooling, humidification and spray
coating. Several techniques are commonly used to measure and characterize collections of drops as
found in sprays, and a substantial body of terminology has envolved to describe liquid drops, drop
populations, sprays and spray devices; all of which are of interest to the users of liquid atomizers,
spray instruments, and data. This standard lists terms commonly encountered in the literature on liquid
drops and sprays and provides definitions specific to the subject area.
1. Scope 1.3.5 Terms pertaining to instruments and test procedures
utilized in the characterization of liquid particles and sprays.
1.1 In a broad sense, this standard covers terminology
associated with liquid particles dispersed in gas. The principal
2. Referenced Documents
emphasis, however, is on particles produced by the process of
2.1 ASTM Standards:
atomization.
D 1356 Terminology Relating to Sampling and Analysis of
1.2 All terms, followed by their definitions, are arranged
Atmospheres
alphabetically. In addition, the standard contains several tables
E 799 Practice for Determining Data Criteria and Process-
wherein terms related to specific subjects are segregated and
ing for Liquid Drop Size Analysis
identified.
1.3 Within the broad scope, the following specific catego-
3. Terminology
ries are included:
aerating nozzle—a device to atomize liquid for the purpose of
1.3.1 Terms pertaining to the structure and condition of
aeration.
individual particles or groups of particles as observed in nature.
1.3.2 Terms pertaining to the structure and condition of
NOTE 1—Although this term is occasionally used to designate certain
individual particles or groups of particles produced by an
types of airblast or internal mixing pneumatic atomizers, it is ambiguous
atomizing device.
and is not recommended for describing the latter devices.
1.3.3 Terms pertaining to atomizing devices according to
aerodynamic diameter—the diameter of a hypothetical
the primary energy source responsible for spray development.
sphere having a specific gravity of unity and the same
(When more than one term is used for the same device or class
settling velocity as the actual particle.
of devices, the alternative term is followed by the preferred
aerosol, n—a dispersion of solid particles or liquid particles, or
term.) Definitions of the devices may refer to their construc-
both, in gaseous media. (D 1356)
tion, operating principle or distinctive spray characteristics.
air assist nozzle—a pneumatic atomizer in which pressurized
The atomizers, however, are not classified by their respective
air is utilized to enhance the atomization produced by
areas of application or end use. Moreover, the listed terms are
pressurized liquid. The air may be required only for part of
generic and do not include brand names, trademarks, or
the operating range (for example, low liquid flow rates).
proprietary designations.
air atomizing nozzle—see pneumatic atomizer.
1.3.4 Terms pertaining to statistical parameters involving
air blast nozzle—see airblast nozzle.
particle measurement, particle size, and size distribution func-
airblast nozzle—a pneumatic atomizer that utilizes a relatively
tions.
large volume of low-pressure air.
This terminology is under the jurisdiction of ASTM Committee E-29 on
Particle Size Measurement and is the direct responsibility of Subcommittee
E 29.04on Liquid Particle Measurement.
Current edition approved April 10, 1997. Published November 1997. Originally Annual Book of ASTM Standards, Vol 11.03.
published as E 1620 – 94. Last previous edition E 1620 – 96a. Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1620
TABLE 1 Summary of Atomizer Terms
Pressure Atomizer (hydraulic atomizer, pressure atomizing nozzle, Lubbock nozzle
pressure nozzle, single-fluid atomizer) variable orifice poppet nozzle (variable orifice pintle nozzle)
Cone Atomizer (cone spray nozzle)
Hollow Cone Atomizer Pneumatic Atomizer(air atomizing nozzle, blast nozzle, gas atomizer, gas-
Solid Cone Atomizer (full cone nozzle) liquid nozzle, twin-fluid atomizer, two-fluid atomizer.)
Deflector Atomizer (flood nozzle, flooding nozzle) air assist nozzle
dual orifice nozzle (duple nozzle) airblast nozzle (air blast nozzle,
duplex nozzle aerating nozzle)
piloted airblast nozzle (simplex airblast nozzle)
Fan Spray Atomizer: prefilming airblast nozzle
Even Spray Atomizer (even flow atomizer)
Flat Spray Atomizer (flat jet atomizer) External Mixing Pneumatic Atomizer
Laskin nozzle
Fog Nozzle
Internal Mixing Pneumatic Atomizer
Impact Atomizer: (impingement atomizer): (aerating nozzle
pintle atomizer Nukiyama-Tanasawa nozzle
splash cup atomizer effervescent atomizer)
splash plate atomizer
Centrifugal Atomizer (rotary atomizer, slinger)
Impinging Jet Atomizer (impingement atomizer): rotary cup atomizer (spinning cup atomizer)
doublet atomizer rotary disk atomizer (spinning disk atomizer)
triplet atomizer rotary wheel atomizer
Plain Jet Atomizer (orifice atomizer, plain orifice atomizer, single jet atomizer, Vibratory Atomizer (vibrative atomizer)
straight stream nozzle) electromagnetic vibratory atomizer
simplex nozzle piezoelectric vibratory atomizer
Square Spray Nozzle Berglund-Liu atomizer
sonic nozzle
Swirl Atomizer ultrasonic nozzle
Swirl chamber atomizer (centrifugal pressure nozzle, swirl chamber vibrating needle atomizer
atomizer) vibrating reed atomizer
by-pass nozzle (bypass nozzle, flowback nozzle, recirculating nozzle, return
flow nozzle, spill nozzle, spill return nozzle, spillback nozzle) Electrostatic Atomizer
dual orifice nozzle (duplex nozzle)
duplex nozzle Shear Coaxial injector
simplex nozzle swirl coaxial injector
Variable-Area Nozzle
Siphon Nozzle (aspirating nozzle)
Sonic Nozzle (sonic-whistle atomizer, ultrasonic nozzle)
TABLE 2 Characteristic Particle Diameters and Distribution
atomization, n—the process of atomizing.
Functions
atomize, v—to transform bulk liquid or slurry into particles.
Aerodynamic Diameter
atomizer, n—a device for atomizing.
Area (surface) Mean Diameter
Berglund-Liu atomizer—a vibratory atomizer in which a
D D D D
Nf, Lf, Af, Vf
De Brouckere Diameter piezoelectric transducer transmits high-frequency oscilla-
Equivalent Volume Sphere
tions to a liquid stream discharged through an orifice,
Diameter
creating relatively uniform drops whose size is a function of
Evaporative Diameter
Herdan Diameter
the frequency of oscillation and the flow rate of the liquid
Linear (arithmetic) Mean Diameter
through the orifice.
Log Normal Distribution
blast nozzle—see pneumatic atomizer.
Mean Diameters
Normal Distribution
breakup, n—liquid disintegration that occurs during atomiza-
Nukiyama-Tanasawa Distribution
tion.
Relative Span
breakup length, n—the distance between the liquid discharge
Rosin-Rammler Distribution
Sauter Mean Diameter
point of an atomizing device and the point where liquid
Square Root Normal Distribution
breakup commences.
Stokes’ Diameter
Upper Limit Log Normal bypass nozzle—see by-pass nozzle.
Distribution
by-pass nozzle—a swirl chamber atomizer containing by-pass
Volume Mean Diameter
orifice(s) or port(s) through which part of the inlet liquid
may be withdrawn from the swirl chamber and returned to
the supply tank or pressure pump suction. The discharge
flow is modulated by controlling the pressure in the bypass
NOTE 2—The term is occasionally used to designate the entire class of
line, using a valve in the line.
pneumatic atomizers.
cavitation, n—the formation of vapor-filled cavities in the
aspirating nozzle—see siphon nozzle. interior or on the solid boundaries of liquids in motion where
E 1620
the pressure is reduced to a critical value without a change in doublet injector—an impinging jet atomizer in which there
ambient temperature. are two colliding liquid jets.
centrifugal atomizer—a device wherein a rotating solid drop, n—a single liquid particle having a generally spheroidal
surface is the primary source of energy utilized to produce a shape.
spray. droplet, n—see drop; also a small drop.
dual orifice nozzle—a swirl chamber atomizer containing a
NOTE 3—Alternatively, an atomizer that rotates to distribute the liquid.
primary injector and a concentric annular secondary injector,
centrifugal pressure nozzle—see swirl chamber atomizer.
each injector comprising a separate orifice and set of
circumferential patternation, n—measurements taken in a
tangential slots. The nozzle is normally operated only with
circumferential direction, showing the variation in liquid
the primary injector at low flow rates, with secondary liquid
flux about the nozzle axis.
introduced at a specified pressure. (This definition applies to
cloud, n—any collection of particulate matter in the atmo-
devices used in the gas turbine industry.)
sphere dense enough to be perceptible to the eye, especially
duple nozzle—see dual orifice nozzle.
a collection of water drops. (D 1356)
duplex nozzle—a swirl chamber atomizer comprising a single
coalescence, n—the merging of two or more liquid particles to
discharge orifice and two sets of tangential slots, each with
form a single liquid particle.
a separately controlled liquid supply. The smaller (primary)
concentration—see number density.
slots supply liquid at low flow rates, and both sets (primary
cone atomizer—an atomizer that produces a conical spray
and secondary) are utilized as flow increases.
pattern.
effervescent atomizer—an internal mixing pneumatic atom-
cone pattern, n—a diverging spray pattern that is nominally
izer in which gas bubbles are dispersed in the liquid stream.
symmetric about the nozzle axis and whose apex is located
electromagnetic vibratory atomizer—a vibratory atomizer in
at or near the nozzle discharge orifice.
which an electromagnetic transducer transmits high-
cone spray nozzle—see cone atomizer.
frequency oscillations to the liquid.
convolution—the combination of local measurements of drop
electrostatic atomizer—a device wherein an electric charge is
size distribution and number density into equivalent line-of-
the primary source of energy utilized to produce a spray.
sight values of drop size distribution and optical extinction.
emitting spray angle, n see initial spray angle.
D ,D ,D ,D —diameters such that the cumulative num-
equivalent volume sphere diameter—the diameter of a hy-
Nf Lf Af Vf
ber of particles, (N), length of diameter, (L), surface area,
pothetical sphere having the same volume as the actual
(A), or volume, (V), from zero diameter to these respective
particle.
diameters is the fraction, (f), of the corresponding sum for
even flow atomizer—see even spray atomizer.
the total distribution.
even spray atomizer—a fan spray atomizer that produces a
relatively uniform band of liquid, usually by means of
Example:
injection, through an elliptical orifice. (This definition ap-
D is the volume median diameter; that is, 50 % of the
V0.5
plies to devices utilized in the agricultural industry.)
total volume of liquid is in drops of smaller diameter and 50 %
external mixing pneumatic atomizer—a pneumatic atomizer
is in drops of larger diameter.
in which pressurized gas is directed on a liquid film or jet
deconvolution—a procedure by which line-of-sight measure-
outside the nozzle, so as to form a spray.
ments of drop size distribution and optical extinction are
fan pattern, n—a spray pattern in which the liquid flux is
converted into local representations of the distribution and
concentrated in a narrow oval or ellipse in a plane perpen-
number density.
dicular to the spray axis.
DISCUSSION—For sprays whose drop size distributions are axisym-
fan spray atomizer—a pressure atomizer that produces a flat
metric in space, an Abel inversion procedure has been used to perform
sheet of liquid that collapses into particles. The angle or
the deconvolution.
width of the sheet is controlled by the shape of a slot or oval
deflector atomizer—an atomizer in which a liquid jet spreads
discharge orifice, by an external deflector, or by impinging
out over a solid surface, forming a spray whose shape
jets.
depends upon the solid surface.
flat jet atomizer—see flat spray atomizer.
dispersion, n—a system of particles distributed in a solid,
flat spray atomizer—a fan spray atomizer that produces a
liquid or gas.
planar spray pattern.
dispersion, n—the spread of values of a frequency distribution
NOTE 4—In agricultural applications, the spray patterns have tapered
about an average (in statistics). (Quantitative measures of
edges.
dispersion include range, variance, standard deviation, mean
deviation and relative span.) flood nozzle—see deflector atomizer.
flooding nozzle—see deflector atomizer.
flowback nozzle—see by-pass nozzle.
flux—the number of particles flowing through a given area per
Hammond, D.C., “A Deconvolution Technique for Line-Of-Sight Optical
Scattering Measurements in Axisymmetric Sprays,” Applied Optics, Vol 20, Number
unit time.
3, February 1981, pp 493–499; Yule, A.J., Ah Seng, C., Felton, P.G., Ungut, A., and
flux-sensitive—a sampling process where the magnitude mea-
Chigier, N.A., “A Laser Tomographic Investigation of Liquid Fuel Sprays,”
sured responds to the flux of particles through the sampling
Eighteenth Symposium-International-on Combustion, Pittsburgh: The Combustion
Institute, 1981, pp 1501–1510. region.
E 1620
flux size distribution—the size distribution of particles pass-
D = the geometric mean diameter,
gm
ing through a sampling zone during a given interval of time,
K = 1/[( 2)s ], and
=
gm
wherein individual particles are counted and sized.
s = the standard deviation of the geometric mean
gm
diameter.
DISCUSSION—Flux size distributions are typically obtained by collec-
tion techniques or by optical instruments capable of sensing individual
DISCUSSION—This does not provide upper bound to D.
particles in flight. Certain sampling methods may provide neither flux
Lubbock nozzle—a variable-area nozzle in which a moveable
size distributions nor spatial size distributio
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