The first spray bottles were engineered sometime in the 20th century – think, vintage perfume bottles with the rubber bulb which is squeezed to apply a fine mist to the wearer. These bottles encapsulated the very  basic idea of spray bottles – using air and a small hole in the nozzle to project liquid into a fine mist through a process called atomising (to change a liquid into very small drops).

Whilst these single pump bottles hung around for a while, the modern day trigger spray bottle became popular in the 1960’s for household use. The increased quality of polymers and their cheap manufacturing costs post WWII, meant that brands like Windex were switching from glass bottles with metal triggers to the shiny plastic bottles that we recognise today.

Liquid Pump

This pump was made up of a trigger, nozzle, piston, sealed chamber, one way valve, tube and the reservoir of liquid as well as a couple of springs.

As observed by the team; when the trigger is pulled or pressed, the piston is pushed into the chamber. This forces the liquid into and out of the chamber,into the nozzle, where it is forced out through the small hole and creating the spray or mist. The one way valve – located in the sealed pressure chamber – only allows water up the tube towards the pump to create an efficient system. A series of springs helps the user to push the trigger in order to move the piston and move the liquid through the system. This is a fairly basic system, the principles involved are used throughout the industry and even in human biology.

This  pump system was used in 5 of our sample sprayers. It was noted that the style of the trigger changed due to the intended use of the bottle to give a variety of uses with the same mechanism.

The spray produced is controlled by the nozzle size to liquid dose ratio. This is important for the function of the bottle; the glass nasal sprayer produced a streamlined direct spray which projected quite far whereas the mist bottle produced a fine mist which dissipated quickly. The larger trigger bottles the team observed had a customizable nozzle which could be in an off, a fine mist or direct spray position depending on the consumers use.

The Flairosol fine mist spray bottle was the most intriguing to the team due to its 1-1.5 second continuous spray feature, which is absent from all the other varieties of sprayers. During the teardown we found the same system as the most basic liquid pump which fed into a second chamber where the water essentially applies pressure to a large spring which causes the pump to be pressed once and a continuous stream of mist is released.

The user experience was good with minimal effort needed to spray the product but some discomfort was noted from the plastic edges of the curved trigger. The mist was fine and projected further than the liquid mist pump so was the most comparable spray to the aerosol can.

Aerosol sprayers

The aerosol combines your liquid product and a propellant in order to achieve a fine mist, the finest of all sprayers that were tested by the team. As we couldn’t open the canister to explore how it works some research was done on the concept.

Your liquid product is placed into the can and the propellant is added under pressure. The propellant is normally a gas at room temperature but becomes a liquid when pressurises. This allows the product to mix with the propellant. When the user goes to spray the shaken can, the propellant becomes a gas again and evaporates leaving behind a fine mist of the product.

The team mentioned how the aerosol was the only sprayer that was unable to be refilled so would be disposed of when the product is used. It also contains VOCs which contribute to greenhouse gases so in comparison to the other sprayers, causes more harm to the environment.

Pressure sprayers

Our largest sprayer was a hand pumped sprayer which held 2L of liquid.The hand pump which is powered by the user builds up the pressure of the air in the tank above the liquid. The pressure pushes this liquid down which forces it up the tube and through a one way valve. The trigger can then be pulled, releasing another valve and allowing the user to control the water coming out of the nozzle.

In conclusion…

The collection of sprayers were evaluated on the ease of use, comfort, quality of mist and the mechanisms involved. The teardown gave a detailed look at the placement of the components needed to make the sprayers work and has provided the team with a good place to start on the new project.

BLOG POST WRITTEN BY SABRINA SKILLING

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