CHE Around Us: Aerosol-Can
by Inra Sumahamijaya on 07/12/08 at 2:10 am | 3 Comments | |
Aerosol-can was invented by Eric Rotheim, a Norwegian engineer and inventor, 75 years ago. The illustrations in Rotheim’s 1931 U.S. patent showed most of the major elements found in today’s aerosol spray cans. In World War II, U.S. military introduced an aerosol-can for dispensing insecticide and years after that, people just begin to realize the potentials of this device and manufacturers adapted this technology for a wide range of applications. Today, thousands of products are packaged in aerosol cans – everything from hair spray to cooking oil and even medicine.
An aerosol is made up of several basic components: (1) an aerosol can, (2) the product, (3) the propellant, (4) a valve with dip tube, and (5) an actuator.
An aerosol-can can be defined as:
“An integral ready-to-use package incorporating a valve and a product which is dispensed by pre-stored pressure in a controlled manner when the valve is operated”
Aerosol-can works in a basic concept: one high-pressure fluid expands to force another fluid through a nozzle. Initially, it was inspired by self pressurized carbonated beverages that can create an expanded pressure. Table below will describe some history from inspiring self pressurized carbonated beverages introduction until recent date now.
| Date | Landmark/Event |
|---|---|
| 1790 | Self-pressurized carbonated beverages introduced in France. |
| 1825 | Charlie Plinth introduced the Regency portable fountain, a device to dispense carbonated beverages using the gas (carbon dioxide) pressure. |
| 1837 | An early soda siphon incorporating a valve was invented by Perpigna. |
| 1899 | Helbling & Pertsch patented aerosols pressurized using methyl and ethyl chloride as propellant. |
| 1929 | Erik Rotheim (Norway) invented early aerosol cans and valves that would hold and dispense a variety of product and propellant systems. These were the forerunner of the modern aerosol and valve. |
| 1933 | Early aerosol fire extinguishers were developed for use in motor cars, by Midgely (General Motors). |
| 1942 | Lyle D. Goodhue & Sullivan developed the first aerosol insecticides, and these were used by US soldiers in World War 2. |
| 1945 | Throw away cans & valves developed. |
| 1947 | Aerosol contract filling begins in the USA. |
| 1949 | First automated filling lines introduced into the UK. |
| 1950 | Rapid growth of the aerosol industry begins in the UK, expanding from only a few thousands of cans per year, to in excess of 1.5 billion in 1997. |
| 1974 | This year saw the publication of the ‘Ozone Depletion Theory’, put forward by two American scientists, Rowland and Molina. The theory said that chlorine containing chemicals, stable in the lower atmosphere, would break down in the stratosphere under the influence of ultra violet light, and act as catalysts in the destruction of ozone. At this time chlorine containing propellants (CFCs) were used in many, but not all, aerosol products. |
| 1975 | Publication of the EEC Aerosol Directive. This Directive is of major importance to the aerosol industry in Europe, and sets out the requirements for construction, performance, testing, filling and labeling of metal, plastic and glass aerosol containers. |
| 1985 | Discovery that the ozone layer above the Antarctic was thinning, confirming the theory put forward by Rowland and Molina. |
| 1987 | 70 nations sign the ‘Montreal Protocol’. This agreement set target dates for significant reductions in the use of CFCs. The protocol was revised in 1990, in order to phase out the use of CFCs by the year 2000. CFC propellants are now only used in certain ‘exempt’ products. |
| 1994 | Revisionof the EEC Aerosol Directive, concerning the flammability labeling of aerosols. |
| 1997 | New BAMA recommendation of July 1997 for the labeling of all UK aerosols, concerning solvent abuse. |
From aerosol concept’s, one fluid stored under high pressure is used to propel another fluid out of a can, the contents of the aerosol are made up of two components:
- The propellant, fluid that boils well below room temperature, which can be a liquefied gas, or even a compressed gas.
- The product, in the form of a liquid, emulsion or suspension that boils at a much higher temperature.
Eric Rotheim
The ‘Classic’ aerosol delivers the product in the form of a spray, which may be made up of small, medium or large droplets, depending upon the function of the aerosol. As an example, an air freshener will consist of very small droplets in order to disperse a fragrance into the air; a furniture polish will consist of larger droplets, as it is only necessary to deliver the spray to a surface. Other aerosol formats include, foams, gels, etc. The outlet product depends on several factors, including:
- The chemical makeup of the propellant and product
- The ratio of propellant to product
- The pressure of the propellant
- The size and shape of the valve system
The choice of these components is critical, and fortunately the manufacturers are able to produce a wide variety of aerosol devices by configuring these elements in different combinations.
In all cases it is the propellant pressure within the can that pushes the product through the various components until it reaches the actuator and emerges as a spray, or one of the other formats. The way in which the liquid is turned into a spray depends on a number of factors which include:
- The valve specification
- The actuator specification
- The type and amount of propellant
There are two ways to configure this aerosol system based on the propellants: (1) Liquefied Propellants, and (2) Compressed Gas Propellants.
3 Comments
michaeljubel
Dec 7th, 2008
Great stuff. It seems that chemical engineering is prominently ubiquitous.
Mark
Dec 20th, 2008
The ‘Classic’ aerosol delivers the product in the form of a spray, which may be made up of small, medium or large droplets, depending upon the function of the aerosol.
Inra Sumahamijaya
Dec 29th, 2008
Yes, and the droplets depends on its actuator
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