Expert: Daniel Mazur - 10/21/2008

Question
Thank you for your time!
I am 31 and have a undergraduate degree.
How can i vary the length and width of a rubber or plastic insert/tube /valve that is insert inside a garden house to create a garden hose that sequentially inflates from one end to the other  having 5 sections. For example,the second chamber won't inflate until the first chamber reaches a set pressure and then the third chamber won't inflate until the second chamber has achieved the same pressure as the first chamber and so on.  At the end each chamber will have equal pressures once completely inflated.

Answer
Hi Mark,
I cannot give you the exact solution, it is more a task for a civil engineer. What you need is to equip each chamber with a pressure sensor (could be as simple as a balloon, whose size is proportional on the pressure in the range you work with) and a simple open-close valve between each two chambers. A sophisticated way would be using electrical pressure sensors and electrically triggered valves, but that is not a solution fit for a garden house. Maybe you could do something with the balloon and a mechanical valve with a long switch arm. The valve needs to be the kind that does not close back, when the pressure in the preceding chamber drops. You could have the inflating balloon push on the switch lever knowing that at the desired pressure it will have such size that it snaps the respective valve open.
This is a solution in principle, but the ideal implementation bay be quite different depending on your stocks of material, budget, what can be found on the market etc. Like I said, you need to ask an engineer specializing in pneumatic/hydraulic systems for a proper solution.
Cheers,
Daniel