Spray (liquid drop)

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Aerosol spray can Aerosol.png
Aerosol spray can

A spray is a dynamic collection of drops dispersed in a gas. [1] The process of forming a spray is known as atomization. A spray nozzle is the device used to generate a spray. The two main uses of sprays are to distribute material over a cross-section and to generate liquid surface area. There are thousands of applications in which sprays allow material to be used most efficiently. The spray characteristics required must be understood in order to select the most appropriate technology, optimal device and size. [2]

Contents

Formation

Spray atomization can be formed by several methods. The most common method is through a spray nozzle which typically has a fluid passage that is acted upon by different mechanical forces that atomize the liquid. [3] The first atomization nozzle was invented by Thomas A. DeVilbiss of Toledo, Ohio in the late 1800s. His invention was a bulb atomizer that used pressure to impinge upon a liquid, breaking the liquid into a fine mist. Spray formation has taken on several forms, the most common being, pressure sprayers and centrifugal, electrostatic and ultrasonic nozzles.

Characteristics

Spray nozzles are designed to perform under various operating conditions. The following characteristics should be considered when selecting a nozzle: [4]

Pattern

Selecting a nozzle based on the pattern and other spray characteristics that are required generally yields good results. [5] Since spray nozzles are designed to perform under many different spraying conditions, more than one nozzle may meet the requirements for a given application. Surfaces may be sprayed with any pattern shape. Results are fairly predictable, depending on the type of spray pattern specified. If the surface is stationary, the preferred nozzle is usually some type of full cone nozzle, since its pattern will cover a larger area than the other styles. Spatial applications, in which the objective is not primarily to spray onto a surface, are more likely to require specialized spray characteristics. Success in these applications is often completely dependent on factors such as drop size and spray velocity. Evaporation, cooling rates for gases and solids, and cleaning efficiency are examples of process characteristics that may depend largely on spray qualities.

Flat fan, solid cone and hollow cone spray patterns Spray patterns.png
Flat fan, solid cone and hollow cone spray patterns

Each spray pattern is described below with typical end use applications.

Solid stream

This type of nozzle provides a high impact per unit area and is used in many cleaning applications, for example, tank-cleaning nozzles (fixed or rotary).

Hollow cone

This spray pattern is a circular ring of liquid. The pattern is achieved by the use of an inlet orifice tangential to a cylindrical swirl chamber that is open at one end. The circular orifice exit has a diameter smaller than the swirl chamber. The whirling liquid results in a circular shape; the center of the ring is hollow. Hollow cone nozzles are best for applications requiring good atomization of liquids at low pressures or when quick heat transfer is needed. These nozzles also feature large and unobstructed flow passages, which provide a relatively high resistance to clogging. Hollow cone nozzles provide the smallest drop size distributions. The relative range of drop sizes tends to be narrower than other hydraulic styles.

The hollow cone pattern is also achievable by the spiral design of nozzle. This nozzle impinges the fluid upon a protruding spiral. This spiral shape breaks the fluid apart into several hollow cone patterns. By altering the topology of the spiral the hollow cone patterns can be made to converge to form a single hollow cone.

Full cone

Full cone nozzles yield complete spray coverage in a round, oval or square shaped area. Usually the liquid is swirled within the nozzle and mixed with non-spinning liquid that has bypassed an internal vane. Liquid then exits through an orifice, forming a conical pattern. Spray angle and liquid distribution within the cone pattern depend on the vane design and location relative to the exit orifice. The exit orifice design and the relative geometric proportions also affect the spray angle and distribution. Full cone nozzles provide a uniform spray distribution of medium to large size drops resulting from their core design, which features large flow passages. Full cone nozzles are the style most extensively used in industry.

Flat spray

As the name implies, the spray pattern appears as a flat sheet of liquid. The pattern is formed by an elliptical or a round orifice on a deflective surface that is tangent to the exit orifice. The orifice has an external groove with a contoured internal cylindrical radius, or “cat's eye” shape. In the elliptical orifice design, the pattern sprays out of the orifice in line with the pipe. In the deflector design, the spray pattern is perpendicular to the pipe. There are two categories of flat spray, tapered and even, depending on the uniformity of the spray over the spray pattern. Flat spray patterns with tapering edges are produced by straight-through elliptical spray nozzles. This spray pattern is useful for overlapping patterns between multiple nozzle headers. The result is uniform distribution across the entire sprayed surface. Non-tapered flat spray nozzles are used in cleaning applications that require a uniform spray pattern without any overlap in spray area.

Multiple plume spray MultiplePlumes.png
Multiple plume spray

Multiple plume spray

Multiple plume sprays are routinely used in automotive injectors. The multiple plumes are primarily used to provide for the optimal mixing of fuel and air so as to reduce pollutant emission under different operating conditions. The multiple plume automotive injectors can have anywhere from 2 to 8 plumes. The precise location of the centroid of these plumes, the individual plume angles, and the percentage split of the liquid amongst the plumes are normally obtained using an optical patternator.

Capacity

Spray nozzle manufacturers all tabulate capacity based on water. Since the specific gravity of a liquid affects its flow rate, the values must be adjusted using the equation below, where Qw is the water capacity and Spg is the specific gravity of the fluid used resulting the volumetric flow rate of the fluid used Qf.

Nozzle capacity varies with spraying pressure. In general, the relationship between capacity and pressure is as follows:

where Q1 is the known capacity at pressure P1, and Q2 is the capacity to be determined at pressure P2.

Spray impact

Impact of a spray onto the target surface is expressed as the force/area, N/m2 or lb/in2. This value depends on the spray pattern distribution and the spray angle. Generally, solid stream nozzles or narrow spray angle flat fan nozzles are used for applications in which high impact is desired, such as cleaning. When a nozzle is used for cleaning, the impact or pressure is called impingement. As with all spray patterns, the unit impact decreases as the distance from the nozzle increases, thereby increasing the impact area size.

The spray impact, , depends on the volumetric flowrate Q and pressure drop according to the equation below. The nozzle type and distance between the nozzle and surface affect the constant C.

Spray angle and coverage

The spray angle diverges or converges with respect to the vertical axis. As illustrated in the figure below, the spray angle tends to collapse or diverge with increasing distance from the orifice. Spray coverage varies with spray angle. The theoretical coverage, C, of spray patterns at various distances may be calculated with the equation below for spray angles less than 180 degrees. The spray angle is assumed to remain constant throughout the entire spray distance. Liquids more viscous than water form smaller spray angles, or solid streams, depending upon nozzle capacity, spray pressure, and viscosity. Liquids with surface tensions lower than water produce wider spray angles than those listed for water. Spray angles are typically measured using optical or mechanical methods. The optical methods include shadowgraphy, extinction tomography, and Mie Imaging. [6] Sprays angles are important in coating applications to prevent overspraying of the coated materials, in combustion engines to prevent wetting of the cylinder walls, and in fire sprinklers to provide adequate coverage of the protected property.

Spray coverage Spray coverage.png
Spray coverage

Spray drop size

The drop size is the size of the spray drops that make up the nozzle's spray pattern. [7] The spray drops within a given spray are not all the same size. There are several ways to describe the drop sizes within a spray:

Sauter Mean Diameter (SMD) or D32

• Volume Median Diameter (VMD) DV0.5 and Mass Median Diameter (MMD)

Drop sizes are stated in micrometers (µm). One micrometer equals 1/25,400 inch.

Drop size distribution

The size and/or volume distribution of drops in a spray is typically expressed by the size versus the cumulative volume percent.

Cumulative drop size distribution graph Size distribution wiki.png
Cumulative drop size distribution graph

Relative span factor

Comparing drop size distributions from alternate nozzles can be confusing. The Relative Span Factor (RSF) reduces the distribution to a single number. The parameter indicates the uniformity of the drop size distribution. The closer this number is to zero, the more uniform the spray will be (i.e. tightest distribution, smallest variance from the maximum drop size, Dmax, to the minimum drop size, Dmin ). RSF provides a practical means for comparing various drop size distributions.

Drop size measurement

Sprays are typically characterized by statistical quantities obtained from size and velocity measurements over many individual droplets. The most widely used quantities are size and velocity probability density distributions as well as fluxes, e.g., number, mass, momentum etc. Through a given plane, some instruments infer such statistical quantities from individual measurements, e.g., number density from light extinction, but very few instruments are capable of making direct size and velocity measurements of individual droplets in a spray. [8] The three most widely used methods of drop size measurements are laser diffraction, optical imaging, and phase Doppler. All of these optical methods are non-intrusive. If all the drops had the same velocity, the measurements of drop size would be the identical for all methods. However, there is a significant difference between the velocity of larger and smaller drops. These optical methods are classified as either spatial or flux based. A spatial sampling method measures the drops in a finite measurement volume. The residence time of drops in the measurement volume affects the results. The flux-based methods sample continually over a measurement cross-section.

Laser diffraction, [9] a spatial sampling method, relies on the principle of Fraunhofer diffraction, which is caused by the light interacting with the drops in the spray. The scattering angle of the diffraction pattern is inversely related to the size of the drop. This nonintrusive method utilizes a long cylindrical optical probe volume. The scattered light passes through a special transforming lens system and is collected on a number of concentric photodiode rings. The signal from the photodiodes is used to back-calculate a drop size distribution. A number of lenses allow measurements from 1.2 to 1800 µm.

The optical imaging method uses a pulsed light, laser or strobe, to generate the shadow graphic image used to determine the size of the drop in the measurement volume. This spatial measurement method has a range from 5 µm to 10,000 µm with lens and optical configuration changes. Image analysis software processes the raw images to determine a circular equivalent drop diameter. This method is best suited to quantify larger diameter drops in medium to low density sprays, opaque liquids (slurries), and ligaments (partially formed drops).

Phase Doppler, [10] a flux-based method, measures particle size and velocity simultaneously. This method, also known as PDPA, is unique because the drop size and velocity information is in the phase angle between the detector signals and the signal frequency shift. Because this method is not sensitive to intensity, it is used in more dense sprays. The range of drop sizes is 1 to 8000 µm. At the heart of the method are crossed laser beams that create interference patterns (regular spaced pattern of light and dark lines) and illuminate drops as they pass through the small measurement zone. A series of three off axis detectors collects the optical signal that is used to determine the phase angle and frequency shift caused by the drops.

Optical imaging and phase Doppler methods measure the size of individual drops. A sufficient number of drops (order of magnitude 10,000 drops) must be quantified to produce a representative distribution and to minimize the effect of random fluctuations. Often several measurement locations in a spray are necessary because the drop size varies over the spray cross-section.

Factors affecting drop size

Nozzle type and capacity: full cone nozzles have the largest drop size, followed by flat spray nozzles. Hollow cone nozzles produce the smallest drop size. Spraying pressure: drop size increases with lower spraying pressure and decreases with higher pressure. Flow rate: flow rate has a direct effect on drop size. An increase in flow rate will increase the pressure drop and decrease the drop size, while a decrease in flow rate will decrease the pressure drop and increase the drop size.

Spray angle: spray angle has an inverse effect on drop size. An increase in spray angle will reduce the drop size, whereas a reduction in spray angle will increase the drop size.

Liquid properties: viscosity and surface tension increase the amount of energy required to atomize the spray. An increase in any of these properties will typically increase the drop size.

Within each type of spray pattern the smallest capacities produce the smallest spray drops, and the largest capacities produce the largest spray drops. Volume Median Diameter (VMD) is based on the volume of liquid sprayed; therefore, it is a widely accepted measure

Spray drop surface area density

The drop surface area density is the product of the spray drop surface area and the number of drops per unit volume. The surface area density is very important in evaporation and combustion applications since the local evaporation rate is highly correlated to the surface area density. The extinction of light caused by the drops within a spray is also directly proportion to the surface area density. The two most widely used methods of measuring the surface area density are Laser Sheet Imaging and Statistical Extinction Tomography. [11]

Practical considerations

Drop size data depend on many variables, and are always subject to interpretation. The following guidelines are suggested to facilitate understanding and effective use of the drop size data.

Data collection repeatability and accuracy
an average value drop size test result is repeatable if the data from individual tests do not deviate by more than ±10%; however, this may be larger or smaller depending on several factors. Accuracy requires a primary standard which is not available for spray measurements.
Instrumentation and reporting bias
to make valid data comparisons, particularly from different sources, it is extremely important to know the type of instrument and range used, the sampling technique, and the percent volume for each size class. Instrumentation and reporting bias directly affect drop size data.
Consider the Application
select the drop size mean and diameter of interest that is best suited for the application. If the object is simply to compare the drop size of alternate nozzles, then the VMD or SMD report are sufficient. Additional information such as RSF, DV90, DV10, and others should be used when appropriate.

Applications

Fuel sprays

Sprays of hydrocarbon liquids are among the most economically significant applications of sprays. Examples include fuel injectors for gasoline and diesel engines, atomizers for jet engines (gas turbines), [12] atomizers for injecting heavy fuel oil into combustion air in steam boiler injectors, and rocket engine injectors. Drop size is critical because the large surface area of a finely atomized spray enhances fuel evaporation rate. Dispersion of the fuel into the combustion air is critical to maximize the efficiency of these systems and minimize emissions of pollutants (soot, NOx, CO). [13]

Electrical power generation

Limestone slurry is sprayed with single fluid spray nozzles to control acid gas emissions especially sulfur dioxide (SO2) emissions from coal-fired power plants with liquid scrubbers. Calcium hydroxide (lime) is atomized into a spray dryer absorber to remove acid gases (SO2 and HCl) from coal-fired power plants. Water is sprayed to remove particulate solids using a spray tower or a cyclonic spray scrubber [14] Cooling towers use spray nozzles to distribute water.

Food and beverage

Manufacturing

Sprays are used extensively in manufacturing. [17] Some typical applications are applying adhesive, lubricating bearings, and cooling tools in machining operations.

Paper making

Electronics

Fire protection

Mining

Lime and cement

Steel industry

Chemical, petrochemical, and pharmaceutical

Waste treatment

Agricultural applications

Knapsack sprayer used to sulfate on vegetables. Valencian Museum of Ethnology. Objectes de la Sala Horta i Marjal (27190138015).jpg
Knapsack sprayer used to sulfate on vegetables. Valencian Museum of Ethnology.

Spray application of herbicides, insecticides, and pesticides is essential to distribute these materials over the intended target surface. [20] Pre-emergent herbicides are sprayed onto soil, but many materials are applied to the plant leaf surface. Agricultural sprays include the spraying of cropland, forest, turf grass, and orchards. The sprayer may be a hand nozzle, on a ground vehicle, or on an aircraft. Herbicides, insecticides and pesticides are spray applied to soil or plant foliage to distribute and disperse these materials. See aerial application, pesticide application, sprayer. The control of spray characteristics is critical to provide the coverage of foliage and to minimize off target drifting of the spray to adjacent areas. (pesticide drift). Spray drift is managed by applying only in appropriate wind conditions and humidity, and by controlling drop size and drop size distribution. Minimizing the height of the spray boom above the crop reduces drift. The spray nozzle type and size and the operating pressure provide the correct application rate of the material and control the amount of driftable fines. Spays, single fluid nozzles, are also used to cool animals

Consumer products

Atomizers are used with pump-operated sprays of household cleaning products. The function of these nozzles is to distribute the product over an area. See aerosol spray and spray can

Related Research Articles

<span class="mw-page-title-main">Cavitation</span> Low-pressure voids formed in liquids

Cavitation in fluid mechanics and engineering normally refers to the phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, called "bubbles" or "voids", collapse and can generate shock waves that may damage machinery. These shock waves are strong when they are very close to the imploded bubble, but rapidly weaken as they propagate away from the implosion. Cavitation is a significant cause of wear in some engineering contexts. Collapsing voids that implode near to a metal surface cause cyclic stress through repeated implosion. This results in surface fatigue of the metal, causing a type of wear also called "cavitation". The most common examples of this kind of wear are to pump impellers, and bends where a sudden change in the direction of liquid occurs. Cavitation is usually divided into two classes of behavior: inertial cavitation and non-inertial cavitation.

<span class="mw-page-title-main">Drop (liquid)</span> Small unit of liquid

A drop or droplet is a small column of liquid, bounded completely or almost completely by free surfaces. A drop may form when liquid accumulates at the end of a tube or other surface boundary, producing a hanging drop called a pendant drop. Drops may also be formed by the condensation of a vapor or by atomization of a larger mass of solid. Water vapor will condense into droplets depending on the temperature. The temperature at which droplets form is called the dew point.

<span class="mw-page-title-main">Spray drying</span> Method of converting liquid or slurry to powder

Spray drying is a method of forming a dry powder from a liquid or slurry by rapidly drying with a hot gas. This is the preferred method of drying of many thermally-sensitive materials such as foods and pharmaceuticals, or materials which may require extremely consistent, fine particle size. Air is the heated drying medium; however, if the liquid is a flammable solvent such as ethanol or the product is oxygen-sensitive then nitrogen is used.

Flow measurement is the quantification of bulk fluid movement. Flow can be measured using devices called flowmeters in various ways. The common types of flowmeters with industrial applications are listed below:

<span class="mw-page-title-main">Nozzle</span> Device used to direct the flow of a fluid

A nozzle is a device designed to control the direction or characteristics of a fluid flow as it exits an enclosed chamber or pipe.

<span class="mw-page-title-main">Spray painting</span> Painting technique in which a device sprays coating material through the air onto a surface

Spray painting is a painting technique in which a device sprays coating material through the air onto a surface. The most common types employ compressed gas—usually air—to atomize and direct the paint particles.

<span class="mw-page-title-main">Venturi effect</span> Reduced pressure caused by a flow restriction in a tube or pipe

The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of a pipe. The Venturi effect is named after its discoverer, the 18th-century Italian physicist Giovanni Battista Venturi.

In surface science, a tensiometer is a measuring instrument used to measure the surface tension of liquids or surfaces. Tensiometers are used in research and development laboratories to determine the surface tension of liquids like coatings, lacquers or adhesives. A further application field of tensiometers is the monitoring of industrial production processes like parts cleaning or electroplating.

<span class="mw-page-title-main">Spray bottle</span>

A spray bottle is a bottle that can squirt, spray or mist fluids.

<span class="mw-page-title-main">Venturi scrubber</span> Air pollution control technology

A venturi scrubber is designed to effectively use the energy from a high-velocity inlet gas stream to atomize the liquid being used to scrub the gas stream. This type of technology is a part of the group of air pollution controls collectively referred to as wet scrubbers.

<span class="mw-page-title-main">Spray nozzle</span> Device that facilitates dispersion of liquid into a spray

A spray nozzle or atomizer is a device that facilitates the dispersion of a liquid by the formation of a spray. The production of a spray requires the fragmentation of liquid structures, such as liquid sheets or ligaments, into droplets, often by using kinetic energy to overcome the cost of creating additional surface area. A wide variety of spray nozzles exist, that make use of one or multiple liquid breakup mechanisms, which can be divided into three categories: liquid sheet breakup, jets and capillary waves. Spray nozzles are of great importance for many applications, where the spray nozzle is designed to have the right spray characteristics.

The Institute for Liquid Atomization and Spray Systems, (ILASS), is an organization of researchers, industrial practitioners and students engaged in professional activities connected with the spraying of liquids and slurries. Annual technical conferences are organized by each of the ILASS organizations ILASS-Americas, ILASS-Asia, and ILASS-Europe. ILASS-International is an overarching coordinating board made up of representatives from the three regional ILASS Institutes.

<span class="mw-page-title-main">Ultra-low volume</span>

Ultra-low volume (ULV) application of pesticides has been defined as spraying at a Volume Application Rate (VAR) of less than 5 L/ha for field crops or less than 50 L/ha for tree/bush crops. VARs of 0.25 – 2 L/ha are typical for aerial ULV application to forest or migratory pests. In order to maintain efficacy at such low rates, droplet size must be rigorously controlled in order to minimise waste: this is Controlled Droplet Application (CDA). Although often designed for non-evaporative formulations, ULV equipment may sometimes be adapted for use with water, often at Very Low volume VAR.

<span class="mw-page-title-main">Ultrasonic nozzle</span> Type of spray nozzle

Ultrasonic nozzles are a type of spray nozzle that use high frequency vibrations produced by piezoelectric transducers acting upon the nozzle tip that create capillary waves in a liquid film. Once the amplitude of the capillary waves reaches a critical height, they become too tall to support themselves and tiny droplets fall off the tip of each wave resulting in atomization.

Microdispensing is the technique of producing liquid media dosages in volumes of less than one microlitre. The continuing miniaturization in almost all technical areas creates constant challenges for industry, development and research facilities. Microdispensing is one of those challenges. Ever smaller amounts of adhesive, liquid, oil, grease and a multitude of other media must be dispensed reliably and accurately in dosage and placement with short cycle times. The precise positioning and quantity of fluids such as glue, reagents or any other substance has a great influence on the overall quality of a medical device. A few examples are:

<span class="mw-page-title-main">Analytical nebulizer</span> Type of apparatus that converts liquids into a fine mist

The general term nebulizer refers to an apparatus that converts liquids into a fine mist. Nozzles also convert liquids into a fine mist, but do so by pressure through small holes. Nebulizers generally use gas flows to deliver the mist. The most common form of nebulizers are medical appliances such as asthma inhalers or paint spray cans. Analytical nebulizers are a special category in that their purpose is to deliver a fine mist to spectrometric instruments for elemental analysis. They are necessary parts of inductively coupled plasma atomic emission spectroscopy (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), and atomic absorption spectroscopy (AAS).

A conical plate centrifuge is a type of centrifuge that has a series of conical discs which provides a parallel configuration of centrifugation spaces.

Patternation is the specialized technical art of performing quantitative measurements of specific properties of particles within a spray and visualizing the patterns of this specific property within the spray. In order to understand patternation, we need to consider the role sprays play in our daily lives.

<span class="mw-page-title-main">Inkjet technology</span>

Inkjet technology originally was invented for depositing aqueous inks on paper in 'selective' positions based on the ink properties only. Inkjet nozzles and inks were designed together and the inkjet performance was based on a design. It was used as a data recorder in the early 1950s, later in the 1950s co-solvent-based inks in the publishing industry were seen for text and images, then solvent-based inks appeared in industrial marking on specialized surfaces and in the1990's phase change or hot-melt ink has become a popular with images and digital fabrication of electronic and mechanical devices, especially jewelry. Although the terms "jetting", "inkjet technology" and "inkjet printing", are commonly used interchangeably, inkjet printing usually refers to the publishing industry, used for printing graphical content, while industrial jetting usually refers to general purpose fabrication via material particle deposition.

Rotary atomizers use a high speed rotating disk, cup or wheel to discharge liquid at high speed to the perimeter, forming a hollow cone spray. The rotational speed controls the drop size. Spray drying and spray painting are the most important and common uses of this technology.

References

  1. ASTM standard E-1620 Standard Terminology Relating to Liquid Particles and Atomization
  2. Lipp, Charles W., Practical Spray Technology: Fundamentals and Practice, 2012, ISBN   978-0-578-10090-6
  3. Lipp, Charles W., Practical Spray Technology: Fundamentals and Practice, 2012, ISBN   978-0-578-10090-6
  4. A.H. Lefebvre, Atomization and Sprays, 1989, ISBN   0-89116-603-3
  5. Lipp, Charles W., Practical Spray Technology: Fundamentals and Practice, 2012, ISBN   978-0-578-10090-6
  6. Sivathanu et al., Atomization and Sprays, vol. 20, pp. 85-92.
  7. Rudolf J. Schick, An Engineer’s Practical Guide to Drop Size Spraying Systems Co. [2009]
  8. Kalantari, Davood; Tropea, Cameron (2007-08-17). "Phase Doppler measurements of spray impact onto rigid walls". Experiments in Fluids. 43 (2–3): 285–296. Bibcode:2007ExFl...43..285K. doi:10.1007/s00348-007-0349-4. ISSN   0723-4864. S2CID   119940133.
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  10. H.-E. Albrecht, M. Borys, N. Damaschke, C. Tropea, Laser Doppler and Phase Doppler Measurement Techniques, 2003, ISBN   3-540-67838-7
  11. Lim, J., and Sivathanu, Y., “Optical Patternation of a Multi-hole Fuel Spray Nozzle,” Atomization and Sprays, vol. 15, pp. 687-698, 2005
  12. Lefebvre, A.H. Gas Turbine Combustion, 1999, ISBN   1-56032-673-5
  13. Reitz, Rolf D, Modeling atomization processes in high-pressure vaporizing sprays, Atomization and Spray Technology (ISSN 0266-3481), vol. 3, no. 4, 1987, p. 309-337.
  14. R H Perry, C H Chilton, C W Green (Ed), Perry's Chemical Engineers' Handbook (7th Ed), McGraw-Hill (2007), sections 12.23, ISBN   978-0-07-142294-9
  15. K. Masters, Spray Drying Second Ed, 1976, ISBN   0-7114-4921-X
  16. N. Ashgriz, Handbook of Atomization and Sprays, 2011, ISBN   978-1-4419-7263-7
  17. G.G. Nasr, A.J. Yuhl, L. Bendig, Industrial Sprays and Atomization, 2002, ISBN   1-85233-460-6
  18. Spray Uses in Various Industrial Cleaning Applications http://www.stingraypartswasher.com/Parts_Washer_Cleaning_Application_Solutions.html
  19. C. D. Taylor and J. A. Zimmer, Effects of Water Sprays Used with a Machine-Mounted Scubber on Face Methane Concentrations, SME Annual Meeting Feb 26-28 Denver CO 2001, (https://www.cdc.gov/niosh/mining/pubs/pdfs/eowsu.pdf)
  20. Lipp, Charles W., Practical Spray Technology: Fundamentals and Practice, 2012, ISBN   978-0-578-10090-6