Aerosol Spray Can Notes



The content delivery from aerosols depends on valve assembly, containers, and actuators and on propellant.

Types Of aerosols (aerosol spray)

Pintura en aerosol

Clenil aerosol

Salbutamol aerosol

Fluibron aerosol

rexona clinical

fluimucil aerosol

aerosol Can

Clenil Aerosol


In clenil aerosol Spray the Propellants are used to develop force that expels the product concentrate from the container when valve is opened. Propellants are used to deliver formulation in the proper form (i.e., spray, foam, semisolid).

There are two types of propellant

1. Liquid (liquefied gas) (e.g. chlorofluorocarbons, hydro chlorofluorocarbons, hydro fluorocarbons, hydrocarbon)

a. Chlorofluorocarbon (CFC) propellants

b. Hydro chlorofluorocarbons (HCFC) and Hydro fluorocarbons (HFC)

c. Hydrocarbons

2. Compressed gas (e.g. nitrogen, nitrous oxide or carbon dioxide)

1. Liquefied gases: They are widely used propellants for most of the aerosol products. The temperature and. atmospheric pressure. They are liquefied easily by reducing the temperature and raising the pressure.

When liquefied gas propellants are placed in sealed container. Immediately it get converted into liquid and vapour phase. Due to pressure, liquid phase up in dip tube and against the valve. When valve is opened, immediately sufficient number of molecules changes from liquid to vapour state.

As the liquid is removed from the container through the dip tube, the equilibrium between the propellant’s liquefied phase and vapour phase is rapidly re-established.

Thus, the pressure within the container remains virtually constant and the product may be continuously released at an even rate and with the same propulsion.

a. Chlorofluorocarbon (CFC) propellants

They are also called as Freon’s, P-11 (Trichlorofluoromethane), P-12 (dichlorodifluoromethane), and P-114 (Dichlorotetrafluoro ethane) are the CFCs of choice for oral, nasal, and inhalation aerosols. And inhalation aerosols.

These propellants are used due to their relatively low toxicity and non-inflammable nature.

They are relatively inert.

The CFC’s are gases at room temperature that can be liquefied by cooling them below their boiling point or by compressing them at room temperature.

These liquefied gases also have a very large expansion ratio compared to the compressed gases.

For Several years, the chlorofluorocarbon (CFC) propellants P-11, P-12, and P-114 were used in aerosol products.

But it is found that they deplete the ozone layer of the atmosphere, so their use was restricted.

Instead of P-12, now P-134a and P-227 have been developed which are used in aerosols.

b. Hydro chlorofluorocarbons (HCFC) and Hydro fluorocarbons (HFC) and Hydro fluorocarbons (HFC)

These compounds differ from CFC’s because they have lower ozone depleting effect.

P-22, 142b, and 152a are used in topical p-pharmaceuticals.

They have a greater miscibility with water and therefore are more useful as solvents compared to the other propellants.

c. Hydrocarbons

The hydrocarbons are preferred in topical pharmaceuticals aerosols because of their environmental acceptance and their low toxicity and non-reactive nature.

The hydrocarbons stay on top of the aqueous layer and provide the force to push the contents out of the container.

Their disadvantage is that they are flammable and can explode.

Example-n-butane, isobutene, propane, pentane, hexane.

They are used alone or as mixture form.


2. Compressed gases (Aerosol Spray)

Example: nitrogen, nitrous oxide, and carbon dioxide,

Due to their low expansion ratio, the sprays are fairly wet and the foams that are not stable.

The pressure of the compressed gas contained in the headspace’ of the aerosol container forces the product concentrate out of the container.

There is no. propellant reservoir.

These gases are widely used to dispense food products, dental creams, hair preparations, and Ointments.


Less toxic

Chemically stable


No chances of depletion of ozone layer.


1. Sometime pressure drop during use

2. Not used to get fine spray.


Aerosol containers are made of glass, metals (e.g., tin plated steel, aluminium, and stainless steel), and plastics.

The selection of the container depends on different factors such as production methods, compatibility with the formulation, ability to sustain the pressure necessary for the product, the design and aesthetic appeal, and the cost.

a. Glass containers

They are preferred due to non-corrosive nature and compatible with the most of the formulation when compared to metal containers.

The glass containers must be designed in such a way that they provide the maximum pressure safety and impact resistance.

Mostly coated glass containers are considered safe.

Sometime plastic coatings are commonly applied to the outer surface of glass containers.

These plastic coatings helps to prevent the glass from shattering into fragments if broken and also protect the contents from ultraviolet light.

Glass containers can be easily moulded into different shapes and colours.

Due to transparent property of glass, content can be easily seen in aerosol spray can.

Glass containers range in size from 15 to 30 ml.

Glass containers are generally not used with suspension aerosols.

The glass container have disadvantage because of its fragile nature and also cannot withstand in high pressure more than 15 psig.

b. Tin-plated steel containers

They are light weight and relatively inexpensive.

Special Protective coating (such as oleoresin, phenolic, vinyl, or epoxy coating) are applied to the tin sheets prior to fabrication to protect from corrosion and interaction.

They are used in topical aerosols.

c. aluminium container

Aluminium container of aerosol spray can are used in most Metered Dose Inhalers and many topical aerosols.

They are extremely light Weight and less reactive.

Aluminium containers are coated with epoxy, vinyl, or phenolic resins to reduce interaction with formulation.

These containers have a greater safety against leakage, incompatibility, and corrosion.

Aluminium cont5ainer are made with a 20mm neck finish that adapts to the metered valves.

For special purpose and applications, containers are also available that have neck finishes ranging from 15 to 20 mm.

The container themselves available in sizes ranging from 10 mL to over 1,000 mL.

d. Stainless steel containers

Stainless steel containers of aerosol spray can are strong and can withstand very high pressure.

They are non-reactive.

The limitation of these containers is their high cost and cannot be moulded easily.

e. Plastic containers

They are made of polypropylene or acetyl resins.

They can withstand high pressure.

The non-fragile, light weight and cheap.

They are less used because content of formulation may be absorbed into the surface of container.


VALVES OF Aerosol Spray

The valve is the part of the product package.

Valves are used to emit the contents of the container.

The primary purpose of the valve is to regulate the flow of product concentrate from the container.

The valve must withstand the pressure required by the product concentrate.

The materials used in the manufacture of the various valve parts are plastic, rubber, aluminium, and stainless steel.

The basic parts of a valve assembly of aerosol spray can are;

1. Actuator-It has a button which helps to turning the valve on and off.

In some actuators, mechanical breakup devices are also included.

It is made of plastic.

Actuator may be of different types such as spray actuator, form actuator, solid stream actuator and metered dose inhalers.

2. Stem:

The stem supports the actuator and delivers the formulation in the proper form to the chamber of the actuator.

It is made of nylon, Delran, brass or stainless steel.

3. Gasket:

The gasket serves to prevent leakage of the formulation.

Gasket hold valve assembly in place.

Mostly natural or synthetic rubber are used.

Buna-N and Neoprene rubber are used as gasket material.

4. Spring:

The spring holds the gasket in place and made of stainless steel.

5. Mounting Cup:

It is also known as ferrule.

It is attached to the aerosol container helps to hold the valve in place.

It may be coated with single or double epoxy or vinyl coating to prevent an undesired interactions.

6. Housing:

It is located directly below the mounting cup serves as the link between the dip tube and the stem and actuator.

With the stem, its orifice helps to determine the delivery rate and the form in which the product is emitted.

7. Dip Tube:

It is made of polyethylene or polypropylene.

The dip tube which extends from the housing down into the product concentrate serves to bring the formulation

From the container to the valve.

The viscosity of the product and its intended delivery to rate dictate the inner dimensions of the dip tube and housing for a particular product.



1. Solution system: It may be two or three phase system,

(a) Two phase systemSalbutamol aerosolaerosol spray

It consist of vapour and liquid phase. If active ingredient is soluble in propellant, no other solvent is required.

If active ingredient is not soluble, then co solvents such as ethanol, acetone, propylene glycol, glycerine, ethyl acetate are used.

They reduce the vapour pressure of system and results in production of larger particles upon spraying.

The two system is commonly used to formulate aerosols for inhalation or nasal application.

(b) Three Phase systemPintura en aerosol

A three phase system composed of a layer of water immiscible liquid propellant, a layer of propellant immiscible liquid (usually water).

Which contain the product concentrate and the vapour phase.

This type of system is used when the formulation requires the presence of a liquid phase that is not propellant miscible.

2. Suspension System

It involves dispersion of active ingredient in the propellant or mixture of propellants.

The rate of settling of dispersed particles can be reduced by adding surfactants or suspending agents.

They are primarily used for inhalation aerosols.


The methods used to manufacture aerosols are the cold fill process and the pressure fill process.

1. Cold fill process:

In the cold fill process, both the product concentrate and the propellant must be cooled to

Temperatures between 30°C to 60°C where they will remain liquefied.

Cold filling apparatus consist of insulated box fitted with copper coils.

The cooling system may be a mixture of dry ice and acetone.

The cold aerosol container is filled with the chilled product concentrate and then the liquefied gas is added.

During the process, air is displaced by the natural evaporation of propellants.

After filling is done, the valve assembly is placed into the container and crimped.

Aqueous solutions cannot be filled e this process because the water will turn to ice in the low temperatures.

2. Pressure fill process:

Pressure filling is carried out essentially at room temperature.

The product concentrate is inserted in the container.

The valve assembly is then placed and crimped.

The liquefied gas, under pressure is introduced through the valve into the container.

After the filling operation is done, the container is removed and move to filling head of high pressure propellant which is similarly filled.

The Pressure filling process is preferred for most pharmaceutical aerosols due to less danger of moisture contamination of the product and also less propellant is lost in the process.


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