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Spray Nozzle Glossary

 

Following are descriptions of terms found throughout our website.  You can click-on the alphabetized list to jump right to a particular definition.  In some cases you can click-on glossary terms to get sent to web pages that describe those topics in more detail.

 

Air Atomizing Spray Nozzles use collision of metered air and liquid to provide the finest atomization of a liquid.

 

Internally Mixed: Air and liquid are mixed inside a nozzle body – for low viscosity and clean fluids.

Externally Mixed: Liquid and air mixing occurs outside of the nozzle – for viscous and fluids with particulate.

 

Droplet Size

 

The precision orifice(s) of spray nozzles are designed to break-up liquid into a multitude of droplets, usually for the purpose of increasing surface area, or concentrating liquid to create high impact force. Droplet size is frequently denoted by a mean of median diameter. The following seven nomenclatures are commonly used to describe droplet size. Each have different numerical values which vary widely. Mass Volume Median Diameter is the largest of all and number median diameter is the smallest. The differences between the various mean and median diameters provide a convenient way of specifying the "spread" of droplet sizes produced. If all the spray droplets had been uniform in size, the mean and median diameters would have been identical with the uniform size. Lechler measures droplet size with a PDPA system.

 

• Arithmetic Mean: The simple weighted average based on the diameters of all the individual droplets in the spray sample.
• Surface Mean: The diameter of a droplet whose surface area, if multiplied by the total number of droplets, will equal the total surface area of all the droplets in the spray sample.
• Sauter Mean: Also referred to as "volume surface mean", is the diameter of a droplet whose ration of volume to surface area is equal to that of the entire spray sample.
• Volume Surface Mean: Also referred to as, "sauter mean" is the diameter of a droplet whose ratio of volume to surface area is equal to that of the entire spray sample.
• Mass (Volume) Median Diameter: The diameter which divides the mass (volume) of spray into two equal halves.
• Surface Median Diameter: The diameter which divides the surface area of the droplets into two equal halves.
• Number Median Diameter: The diameter which divides the number of droplets into two equal halves.

 

Flat Fan Spray Nozzles produce a sharply defined linear spray pattern and high impact force.

 

• Axial Flat Fan Nozzles: Straight through flow design having elliptical orifice.
• Deflector Flat Fan Nozzles: Use a precision machined deflector to sculpt a round orifice and solid stream pattern into a evenly distributed flat fan pattern.

 

Full Cone Spray Nozzles provide uniform distribution of liquid across a circular or square area.

 

• Axial Full Cone Spray Nozzles: Straight through design having a "X" styled vane which provides uniform distribution of liquid.
• Tangential Full Cone Spray Nozzles: A right angle liquid flow design to provide uniform distribution without the need for internal vanes or swirl chambers.

 

Hollow Cone Spray Nozzles provide a finely atomized flow having a pattern shaped like a ring.

 

• Axial Hollow Cone Nozzles: Straight through design having spiral grooves or inclined channels to produce a swirl and atomization.
• Tangential Hollow Cone Nozzles: Utilize a right angle supply of liquid. Swirl and atomization achieved via a swirl chamber.

 

PVDF

 

Polyvinylidene Fluoride, a plastic material that lends itself to injection molding.  As compared to stainless steel, PVDF resists erosion and corrosion better and is generally more compatible with a broad range of chemicals.

 

Solid Stream Spray Nozzles

 

Provide concentrated impact with prolonged pattern stability and integrity prior to liquid break-up.

 

Spray Angle

 

Also referred to as spray width, it is typically measured near the nozzle orifice. As the spray distances increase, the measure of the spray pattern length/diameter become significantly less accurate and dependent upon gravity and ambient conditions such as air friction losses and other external influences affecting the spray pattern trajectory.

 

Spray Width

 

Related to the spray angle, it is typically measured near the nozzle orifice. As the spray distances increase, the measure of the spray pattern length/diameter become significantly less accurate and dependent upon gravity and ambient conditions such as air friction losses and other external influences affecting the spray pattern trajectory.

 

Surface Tension

 

This physical property is related to the resistance of the sprayed liquid to break-up into droplets.  The primary effects of surface tension are spray angle, droplet size and spray distribution.

 

Leidenfrost Phenomenon

 

A cushion of vapor repels liquids from surfaces the temperature of which is above their boiling point.

 

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