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In an earlier openproducts' Instructable four ways were demonstrated to reduce the use of liquid handwash by adapting a hand-powered soap dispenser. These four approaches were:

  1. The Engineer's Approach: reduce the stroke of a soap pump piston;
  2. The Salesman's Approach: dilute the dispenser's soap with water;
  3. The Approach of Self-Control: don't push it too far; and
  4. The Environmentalist's Approach: use tablets of soap instead of liquid handwash.

These four solutions have all been documented in an Instructable that was published in June 2013: 'Cope with Big Soap', which also featured interesting soap dispenser statistics. Purpose of reducing the use of liquid handwash is twofold: use less natural resources and reduce expenses (for households but also for companies or services). The assumption on the reference situation is that users commonly use an amount of liquid handwash equal to a full single stroke of the dispenser's handle.

Now back to the four approaches listed above. Initially, there was also a fifth approach, a second Engineer's Approach, which failed miserably. For that reason it is documented here in the Epic Fail Contest 2015.

About that fifth approach a draft version of that first Soap Instructable read the following text, which over-confidently was written before the actual experiment was executed:

[Draft text, not published because the approach failed]
The Engineer's Approach II: introduce an internal by-pass in the pump's cylinder

This method is non-reversible: in the worst case your dispenser pump will be lost. The idea is to create a by-pass, or rather to introduce a leakage to the cylinder. Once the handle is pressed, part of the soap will leave through the sprayer (the standard routing), but part of the soap will leave through the by-pass and will thus flow back to the container. The hole is best located at the bottom of the cylinder in order not to speed up the piston's wear. A hole of 1 mm (0.04 in) resulted in a supply reduction of x%. An advantage of this approach is that the stroke that the user is experiencing is not being influenced. Attentive users might however still notice that 'something has happened to the soap dispenser'.
[End of draft text]

The picture taken of that first experiment is quite spectacular: it shows the soap squirting through the little hole, back into the container, see above (the round opening was only made to be able to visualize the concept).

The bad news was: the approach didn't work, simply because false air was sucked into the cylinder. It worked once only, and then the pump was dead.

The good news is that a new approach was born when documenting the current Instructable, in a similar but improved concept compared to the failed approach reported here. First tests show an output reduction of 60%, again by applying an internal by-pass. Praise the maker's process of iteration! This concept will be documented soon here at Instructables.

In the meantime, if you like failed projects, feel free to have a look at two earlier openproducts' Instructables about iterative making and sharing:

The next Step in this Instructable shows some more pictures of the failure with the soap pump by-pass.

Step 1: More Pictures of the Failure

As explained in the previous Step, an on-purpose by-pass was made to reduce the soap output of the dispenser. The round hole in the container is only to see what's happening. The picture in the Introduction (first picture) shows what's happening when the dispenser's handle is activated: part of the liquid soap gushes back into the container.

As announced above, a follow-up Instructable will be published soon. Check out openproducts' Twitter account to stay tuned!

That's all for this Instructable. The next and final Step spends some words on the Creative Commons license.

Step 2: License

This Instructable is being made available through a Creative Commons Attribution (CC-BY) license. Republishing this Instructable is allowed, provided it is being attributed properly (cite the name openproducts, link to www.openproducts.org, www.instructables.com/member/openproducts, or the original Instructable. For other arrangements send a Private Message through the instructables member page (www.instructables.com/member/openproducts).

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Bio: Openproducts' focus is on design of new products and on innovative approaches towards improving existing products. Also, quick fixes and on-the-fly repairs are documented here ... More »
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