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Re: [PSUBS-MAILIST] Isn't 'Mini book review.' anymore--pressure test
In einer eMail vom 11.04.2002 07:24:40 (MEZ) - Mitteleurop. Sommerze schreibt jonnie@scarymonsters.net:
Most of the commercial tanks that are used for pressure testing are
fluid-based. This is for the same reasons they hydro test scuba tanks partially
filled with water - an explosive failure is far less dangerous if part of the
volume is filled with water instead of compressed air, which has an amusingly
high kinetic energy content.
Hi folks,
Please be carefull with high pressure air !!! Donīt try this at home !!!
Lets replay the physics:
Take a rubber rop of 1m length, fix it above and add a suffucient weight to strech it let say app. twice itīs length.
(IMPORTANT: the amound of needed weight depents on the rupper and the diameter of the rope ... if you need more then 1kg to do this experiment ... be very carefull indeed !!! Or use a weaker rop please)
Now cut off the weight rapidly! BE CAREFULL !!! The storred energy will set free like an explosion !!!
Lets say that the weight should be the pressure and the rubber the air (medium in the tank) So you can see the following: 1. needs a lot of streching way to reach the finite lenght (means air is highly compressible) 2. Force multiply with the needed way gives the amound of stored potential energy. Setting this energy free its become kinetic energy (highly destructive !!)
Now use a normal rope for the same procedure. Very short strech way to carry the same weight, not spectacular effect when cutting off. That should be the water. (nearly incompressible) Remember force x way gives you the result that the amound of needed energy is extremly less then using air !!! (means you will need less power to run the pump)
The only problem is to measuring the way. Or later to reach and hold exactly the aimed pressure... (exept you do this by using a piston and put weight on it.)
Now take the normal rope cut off 5cm and add this length using the rubber rope. (water with a small air bubble)
You will see that you get an average effect and have less stored energy on the one hand but more way to measure the increase...
Andre. How donīt want to teach you but love dramatic physics.