Observation and Measurement of Aerosol Spray Dispensers Using Digital Microscopes

Advantages and Disadvantages of Aerosol Spray Dispenser Products

Aerosol spray dispenser products, which use gas pressure, have the following advantages and disadvantages.

Advantages of aerosol spray dispenser products

• Easy to use by simply pressing a button.
• Easy to carry around.
• Long-term storage is possible because contents do not become oxidised.
• Safe and sanitary due to dirt-free structures.
• Just the necessary amount can be used.
• It is possible to create finer mist or foam than pump-type dispensers.

Disadvantages of aerosol spray dispenser products

• Containers may burst when left in locations exposed to high temperatures.
• The gas pressure reduces at low temperature, preventing contents from being discharged powerfully.
• Aerosol spray dispensers need to be separated when they are discarded.
• Contents may be left inside when the gas is exhausted first.

Aerosol Spray Dispenser Structure

Differences between Products Shaken/Not Shaken Before Use

Some aerosol spray dispenser products are shaken before use and the others are not, which is determined by the type of liquid and propellant used.

Products shaken before use:

• Products that use liquefied petroleum gas (LPG) or dimethyl ether (DME) as the propellant
• Products in which the propellant does not dissolve in the liquid and thus there are three separate phases
• Products that contain an emulsified liquid
• Products that contain a liquid mixed with powders

Products not shaken before use:

• Products that use a compressed gas, such as nitrogen gas (N₂) and carbon dioxide (CO₂), as the propellant

Differences between Products That Can/Cannot Be Used Upside Down

Some aerosol spray dispensers have a structure that cannot be used upside down, while others have a structure that needs to be used upside down. There are also aerosol spray dispensers that can be used both upright and upside down.

Products that cannot be used upside down:

• Products that spray a contained liquid through a dip tube
  This structure cannot be used upside down because the dip tube tip enters the propellant gas layer.

Products used upside down:

• Products that do not have a dip tube
  This structure cannot be used upright because the propellant gas layer is on top.

Products that can be used upright and upside down:

• Products in which the dip tube is weighted.
  The dip tube tip is always immersed in the liquid phase.
• Products that have a mechanism to discharge a contained liquid not only from the dip tube but also from the hole on the valve side wall (vapor tap)