What is the tip of a spray bottle called?

Device that facilitates dispersion of liquid into a spray

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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.[1]

Spray nozzles can have one or more outlets; a multiple outlet nozzle is known as a compound nozzle. Multiple outlets on nozzles are present on spray balls, which have been used in the brewing industry for many years for cleaning casks and kegs.[2] Spray nozzles range from those for heavy duty industrial uses to light duty spray cans or spray bottles.[3]

Single-fluid nozzles

Single-fluid or hydraulic spray nozzles utilize the kinetic energy imparted to the liquid to break it up into droplets. This most widely used type of spray nozzle is more energy efficient at producing surface area than most other types. As the fluid pressure increases, the flow through the nozzle increases, and the drop size decreases. Many configurations of single fluid nozzles are used depending on the spray characteristics desired.

The simplest single fluid nozzle is a plain orifice nozzle as shown in the diagram. This nozzle often produces little if any atomization, but directs the stream of liquid. If the pressure drop is high, at least 25 bars (2,500 kPa; 360 psi), the material is often finely atomized, as in a diesel injector. At lower pressures, this type of nozzle is often used for tank cleaning, either as a fixed position compound spray nozzle or as a rotary nozzle.

• Plain orifice spray nozzle

The shaped orifice uses a semi spherical shaped inlet and a V notched outlet to cause the flow to spread out on the axis of the V notch. A flat fan spray results which is useful for many spray applications, such as spray painting.

• Flat fan spray pattern spray nozzle

A surface impingement nozzle causes a stream of liquid to impinge on a surface resulting in a sheet of liquid that breaks up into small drops. This flat fan spray pattern nozzle is used in many applications ranging from applying agricultural herbicides to painting.

The impingement surface can be formed in a spiral to yield a spiral shaped sheet approximating a full cone spray pattern or a hollow-cone spray pattern.[4]

The spiral design generally produces a smaller drop size than pressure swirl type nozzle design, for a given pressure and flow rate. This design is clog resistant due to the large free passage.

Common applications include gas scrubbing applications (e.g., flue-gas desulfurization where the smaller droplets often offer superior performance) and fire fighting (where the mix of droplet densities allow spray penetration through strong thermal currents).

• Surface impingement spray nozzle

• Spiral spray nozzle

Pressure-swirl spray nozzles are high-performance (small drop size) devices with one configuration shown. The stationary core induces a rotary fluid motion which causes the swirling of the fluid in the swirl chamber. A film is discharged from the perimeter of the outlet orifice producing a characteristic hollow cone spray pattern. Air or other surrounding gas is drawn inside the swirl chamber to form an air core within the swirling liquid. Many configurations of fluid inlets are used to produce this hollow cone pattern depending on the nozzle capacity and materials of construction. The uses of this nozzle include evaporative cooling and spray drying.

• Pressure swirl spray nozzle

• Spillback Nozzle

One of the configurations of the solid cone spray nozzle is shown in a schematic diagram. A swirling liquid motion is induced with the vane structure, however; the discharge flow fills the entire outlet orifice. For the same capacity and pressure drop, a full cone nozzle will produce a larger drop size than a hollow cone nozzle. The coverage is the desired feature for such a nozzle, which is often used for applications to distribute fluid over an area.

Compound

A compound nozzle is a type of nozzle in which several individual single or two fluid nozzles are incorporated into one nozzle body, as shown below. This allows design control of drop size and spray coverage angle.

• Compound pressure swirl spray nozzle with wide pattern

Two-fluid nozzles

Two-fluid nozzles atomize by causing the interaction of high velocity gas and liquid. Compressed air is most often used as the atomizing gas, but sometimes steam or other gases are used. The many varied designs of two-fluid nozzles can be grouped into internal mix or external mix depending on the mixing point of the gas and liquid streams relative to the nozzle face.

Internal mix nozzles contact fluids inside the nozzle; one configuration is shown in the figure below. Shearing between high velocity gas and low velocity liquid disintegrates the liquid stream into droplets, producing a high velocity spray. This type of nozzle tends to use less atomizing gas than an external mix atomizer and is better suited to higher viscosity streams. Many compound internal-mix nozzles are commercially used; e.g., for fuel oil atomization.

External mix nozzles contacts fluids outside the nozzle as shown in the schematic diagram. This type of spray nozzle may require more atomizing air and a higher atomizing air pressure drop because the mixing and atomization of liquid takes place outside the nozzle. The liquid pressure drop is lower for this type of nozzle, sometimes drawing liquid into the nozzle due to the suction caused by the atomizing air nozzles (siphon nozzle). If the liquid to be atomized contains solids an external mix atomizer may be preferred. This spray may be shaped to produce different spray patterns. A flat pattern is formed with additional air ports to flatten or reshape the circular spray cross-section discharge.

Control of two-fluid

Many applications use two-fluid nozzles to achieve a controlled small drop size over a range of operation. Each nozzle has a performance curve, and the liquid and gas flow rates determine the drop size.[5] Excessive drop size can lead to catastrophic equipment failure or may have an adverse effect on the process or product. For example, the gas conditioning tower in a cement plant often utilizes evaporative cooling caused by water atomized by two-fluid nozzles into the dust laden gas. If drops do not completely evaporate and strike a vessel wall, dust will accumulate, resulting in the potential for flow restriction in the outlet duct, disrupting the plant operation.

• Internal mix two-fluid spray nozzle

• External mix two-fluid spray nozzle

• TwinFluid Nozzle

Rotary atomizers

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. They can also be automatic.

Ultrasonic atomizers

This type of spray nozzle utilizes high frequency (20&#;180 kHz) vibration to produce narrow drop-size distribution and low velocity spray from a liquid. The vibration of a piezoelectric crystal causes capillary waves on the nozzle surface liquid film. An ultrasonic nozzle can be key to high transfer efficiency and process stability as they are very hard to clog. They are particularly useful in medical device coatings for their reliability.[6]

Electrostatic

Electrostatic charging of sprays is very useful for high transfer efficiency. Examples are the industrial spraying of coatings (paint) and applying lubricant oils. The charging is at high voltage (20&#;40 kV) but low current.

Liquid properties

Almost all drop size data supplied by nozzle manufacturers are based on spraying water under laboratory conditions, 21 °C (70 °F). The effect of liquid properties should be understood and accounted for when selecting a nozzle for a process that is drop size sensitive.

Temperature

Liquid temperature changes do not directly affect nozzle performance, but can affect viscosity, surface tension, and specific gravity, which can then influence spray nozzle performance.

Specific gravity

Specific gravity is the ratio of the mass of a given volume of liquid to the mass of the same volume of water. In spraying, the main effect of the specific gravity Sg of a liquid other than water is on the capacity of the spray nozzle. All vendor-supplied performance data for nozzles are based on spraying water. To determine the volumetric flowrate Q, of a liquid other than water the following equation should be used.

Q f = Q w a t e r 1 S g {\displaystyle {Q_{f}}={Q_{water}}{\sqrt {\frac {1}{Sg}}}}

Viscosity

Dynamic viscosity is defined as the property of a liquid that resists change in the shape or arrangement of its elements during flow. Liquid viscosity primarily affects spray pattern formation and drop size. Liquids with a high viscosity require a higher minimum pressure to begin spray pattern formation and yield narrower spray angles compared to water.

Surface tension

The surface tension of a liquid tends to assume the smallest possible size, acting as a membrane under tension. Any portion of the liquid surface exerts a tension upon adjacent portions or upon other objects that it contacts. This force is in the plane of the surface, and its amount per unit of length is surface tension. The value for water is about 0.073 N/m (0. lbf/ft) at 21 °C (70 °F). The main effects of surface tension are on minimum operating pressure, spray angle, and drop size. Surface tension is more apparent at low operating pressures. A higher surface tension reduces the spray angle, particularly on hollow cone nozzles. Low surface tensions can allow nozzles to be operated at lower pressures.

Nozzle wear

Nozzle wear is indicated by an increase in nozzle capacity and by a change in the spray pattern, in which the distribution (uniformity of spray pattern) deteriorates and increases drop size. Choice of a wear-resistant material of construction increases nozzle life. Because many single fluid nozzles are used to meter flows, worn nozzles result in excessive liquid usage.

Material of construction

The material of construction is selected based on the fluid properties of the liquid that is to be sprayed and the environment surrounding the nozzle. Spray nozzles are most commonly fabricated from metals, such as brass, Stainless steel, and nickel alloys, but plastics such as PTFE and PVC and ceramics (alumina and silicon carbide) are also used. Several factors must be considered, including erosive wear, chemical attack, and the effects of high temperature.

Applications

Automotive coating: Automotive coating demands droplets 10&#;100 μm (0.39&#;3.94 mils) in size uniformly deposited on substrate. Applications of spray technology are more pronounced during the course of base and clear coatings process which are encompassed as the last stages in automotive coating. Among others rotary bells mounted on robots and hvlp (high volume, low pressure) sprayers are widely used to paint car bodywork during manufacture.[8] Agricultural spraying may involve hydraulic, twin fluid and rotary nozzles: discussed further under pesticide application.

See also

References

The makeup of a fine mist spray bottle involves a number of different parts. The designs and the name of the parts may vary widely from one manufacturer to another. Still, the principles that all of them use are basically the same.

As a general guide, we can refer to this list to determine the different pieces that build this clever device. Let us try to see what these components are so that we can have a better picture of how to clean them later.

1. Dust Cap
2. Actuator
3. Insert
4. Closure
5. Gasket
6. Pump Mechanism
7. Dip Tube

1. Dust Cap

The Dust Cap is the topmost part of the bottle. It is a safety cap that guards the actuator and the spray hole from dust and other harmful materials. It also keeps you from accidentally pressing the actuator.

The dust cap comes in different materials and finishes. Some people may consider it an adjunct and is prone to being lost. Still, its purpose is obviously quite important too.

We recommend that you refrain from reusing spray bottles that have no dust caps. If possible, look for a replacement cap.

2. Actuator or Trigger

Covered by the Dust Cap, the actuator is the part you press to dispense the bottle&#;s contents. It sticks out of the container like a head.

You might be familiar with lotion dispensers with actuators that are table-shaped, having a thin neck and a flat top. However, the actuator in a fine mist spray bottle is hollowed to hold other components inside of it. In a fine mist spray bottle, the actual spray hole can be found on the face of the actuator too.

3. Insert or Nozzle

The Insert is practically the mouth of a fine mist spray bottle. More than that, however, it is actually the part that defines the spray bottle. This tiny piece is what turns the liquid contents into mist. Its interior consists of multiple channels where the liquid passes through before leaving the container.

The Insert is fitted inside the actuator and only appears as a small hole on its surface.

4. Closure

The closure wraps the spray bottle like a collar right below the actuator. The closure fastens all components together onto the actual bottle. The Dust Cap also rests on top of the closure where it snaps securely in place.

The closure could be smooth, matte or satin. Sometimes it is even designed to appear seamlessly connected to the bottle.

5. Gasket

Even though it is one of the least obvious parts, the gasket is actually a vital piece to the assembly of the spray bottle. The gasket is a thin flat material that serves as a seal to prevent the contents from leaking. It is located at the bottom of the closure in the area where it meets the actual bottle.

The materials used as gasket may vary depending on the substances that it is meant to leak-proof. It goes through tests to ensure its compatibility and reliability.

6. Pump Mechanism

The heart of every fine mist spray bottle is the Pump Mechanism. Unlike the other parts, the pump mechanism is composed of several smaller parts including a piston, a housing cap, a stem, a spring, a seal, and a mother housing.

How the pump works was explained in the earlier part of this article. It is what transfers the liquid contents from the container to the actuator. The alternating actions of pushing down the actuator and letting it spring back up is what powers the pump. Releasing the actuator is what allows the pump to draw the liquid contents from the bottle and fill up its chamber. Consequently, pushing down the actuator is what drives the liquid from the chamber to the Insert and out of the bottle.

Do you notice that when a spray bottle is fresh from the store, it does not expel its contents during the first couple of pressing? That is because of how the pump mechanism works. When a spray bottle is still unused, the pump chamber is still empty. It needs the springing up motion of the actuator to allow it to fill its chamber first. Naturally, the contents will only come out at the second or third press once the chamber has already filled up.

7. Dip Tube

To allow the liquid contents to travel from the bottom of the bottle into the pump, they pass through a thin passage called the Dip Tube.

The Dip Tube is connected to the bottom of the pump and extends to the very bottom of the container. Its bottom is usually cut into a &#;V&#; shape or at a diagonal angle to prevent the tube from clogging.

8. The Bottle / Body

The actual bottle or the body is the largest part of the entire spray bottle. It basically holds the liquid contents and it is also what keeps the container standing upright.

Though the majority of the dispensing parts are made of plastic (except for the spring), the body may be made from a number of materials such as plastic, metal and glass.

In terms of advantages for reusing, we recommend that you choose spray bottles made of glass. Glass has unique adsorbent properties that allow it to hold liquids more effectively than other materials. Learn more about the benefits of glass bottles here.