Exercise: Elaborating the design requirements
In the last step you started to define your approach to the design brief. Now you will start elaborating the design requirements.
Elaborate
List all the design requirements for the wave-powered pump, dividing them into:
- functional, i.e. what the product should do, and
- non-functional, i.e. how it should be done (e.g. safely and reliably).
Decide whether each requirement is essential or desirable.
Note: a link to a model solution can be found at the bottom of the page.
Templates
If you would like to, you can download the Table – Elaborating the design requirements document to use as a template. A few requirements have been filled in for you as an example.
| Requirement | Essential/desirable |
|---|---|
| Functional requirements | |
| Minimum pumping rate 1 litre/hour | Essential |
| Can monitor operation via smart phone | Desirable |
| Non-functional requirements | |
| Should work without servicing for one year | Essential |
Model answer
| Requirement | Essential/ Desirable |
|---|---|
| Functional Requirements | |
|
Minimum water pumping rate (flow rate) should not be less than 1 litres/hour. Maximum pumping height, i.e. maximum height water can be raised above the pump’s level, must not be less than 2 meters. Maximum suction height, i.e. height of pump above water level, must not be less than 0.5 meters. Should have a mechanism for switching on the pump when water level inside the boat reaches a maximum level (a float for example). Should have a mechanism for switching off the pump when water level inside the boat falls below a minimum level (a float for example) Should have protection against the pump running dry (pump outlet sensor for example). Should have protection against blocked outlet (relief or by-pass valve for example). Should have protection against sucking in solid particles that can cause jamming or damage to the pump (inlet filter for example). Should have protection against solid particles going into the pump through the discharge pipe(s) (outlet filter for example). Should have a mechanism for keeping water inside the pump and the inlet pipe(s) when the pump is switched off (non-return valve for example). Maximum installation height of all parts of the system is limited to 2 meters. Maximum weight of entire system should not be greater than 25 Kg. |
Essential |
| Non-Functional Requirements | |
|
Should work without servicing for one year Parts should not rust or corrode when subjected to sea water, water vapour, or drizzle. Should adhere to all fire safety codes and standards. None of the moving parts should pause risk to users (all moving parts should be enclosed properly). Should adhere to all electrical safety codes and standards. Operating noise levels should be kept to a minimum, and adhere to any relevant codes or standards. Vibrations caused by operation of mechanical parts should be kept to a minimum and should adhere to all relevant codes and standards. |
Essential |
|
Should be easy to install and set up without the need for a specialist mechanic. Pump should not jam if it does not operate for long time |
Desirable |
Fundamental Skills in Engineering Design
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