calculating the velocity of a component if burst during pressure testing
calculating the velocity of a component if burst during pressure testing
(OP)
Hello, I am new to this forum and I am designing a Pneumatic Pressure testing system for a double ended DOT 3E 1800 cylinder that is fitted with two needle valves and a quick connect fitting. The sizes of the nozels are all 1/4".
We are looking to pressure it up to 1800 psi with air, while it is placed in a tank full of water so we can open and closed the valves to see if there is any sign of leakage.
I was wondering how I could calculate the velocity a fitting would have if it were to fail. I need this velocity in order to decide what kind of material I can use for the tank itself.
Here is a picture of the set up
We are looking to pressure it up to 1800 psi with air, while it is placed in a tank full of water so we can open and closed the valves to see if there is any sign of leakage.
I was wondering how I could calculate the velocity a fitting would have if it were to fail. I need this velocity in order to decide what kind of material I can use for the tank itself.
Here is a picture of the set up





RE: calculating the velocity of a component if burst during pressure testing
The you can estimate the drag of the water and come up with an impact energy.
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Plymouth Tube
RE: calculating the velocity of a component if burst during pressure testing
Carbon steel is fairly cheap, and any good vessel shop will have CNC plasma and/or acetylene cutting ability. Draw up your box, and order the plate.
RE: calculating the velocity of a component if burst during pressure testing
RE: calculating the velocity of a component if burst during pressure testing
Next question.
RE: calculating the velocity of a component if burst during pressure testing
RE: calculating the velocity of a component if burst during pressure testing
"The stored energy may be calculated using the following formula providing that nitrogen
or air is used as the test medium:
E=2.5 x Pat x V [1 (Pa/Pat)0.286 ]
Where:
E = stored energy in kJ
Pa = absolute atmospheric pressure, 101 kPa
Pat = absolute test pressure in kPa
V = total volume under test pressure in m3"
Does this seem the correct energy release I could excpect if burst? is that what I should have my walls rated at?
RE: calculating the velocity of a component if burst during pressure testing
Trouble is, not all of the PE will be instantaneously released and transformed to the part's KE; it will be apportioned between the rest of the assembly and there will also be some break-away energy that will not be transferred to the part's KE.
If the tank is big enough this might not be an issue anyway. Googling videos about firing a gun under water shows that the bullet only travels a bit over a yard through the water before it comes to a dead stop. If the container can withstand the concussion, it can probably withstand the impact of the projectile.
RE: calculating the velocity of a component if burst during pressure testing
You will want a lid. If this bursts you will blow a 100 gal of water up out of the tank and a lot of people (anyone withing 50') will be mad at you.
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Plymouth Tube
RE: calculating the velocity of a component if burst during pressure testing
It seems that you are concerned with missiles and not with a catastrophic vessel failure. In missile assessment the storage energy in the vessel is also an important input, but other constraints shall be also considered.
Take a look on the British report CRR 168, it is a very valuable reference for this issue.
www.hse.gov.uk/research/crr_pdf/1998/crr98168.pdf
Regards,
HotStab.