Valve, Gas fluid flow question
Valve, Gas fluid flow question
(OP)
Hi all,
I am new here and need your help.
After sudden opening of a ball valve with cross section area of 10 mm come to an blow up (explosion) of the 2" pipe.
(before opening) Up stream the valve was the gas pressure 190 bar during downstream the pressure was 0 bar, however it was air inside (s.attached).
Downstream of the valve the distance to the orifice plate is 1,5 m, there was upstream the OR an blow up of the pipe about 50%.
Could you explain me the physical phenomenon, mathematical equation would be appreciated.
best regards
robin
I am new here and need your help.
After sudden opening of a ball valve with cross section area of 10 mm come to an blow up (explosion) of the 2" pipe.
(before opening) Up stream the valve was the gas pressure 190 bar during downstream the pressure was 0 bar, however it was air inside (s.attached).
Downstream of the valve the distance to the orifice plate is 1,5 m, there was upstream the OR an blow up of the pipe about 50%.
Could you explain me the physical phenomenon, mathematical equation would be appreciated.
best regards
robin





RE: Valve, Gas fluid flow question
I'm going to assume that the 190 bar stream was natural gas? If it is air, then the heat of compression discussion below still reaches the same temperature, but there must be something like grease or residual hydrocarbons to have an explosion.
When the valve opens, the high pressure gas begins to flow at sonic velocity. A sonic stream is very dense and will not mix with a static volume. Instead it will compress the gas in the low pressure system until that gas is about 1/2 the pressure of the upstream. So you've taken the air from 1 bara to 86 bara or 86 compression ratios. The adiabatic heat of compression (see the FAQ's) says that if the air started at 15C it would end up at around 750C. The autoigintion temperature of methane is 538C. In the vernacular, you "dieseled" the line. It happens in meter runs several times a day around the world. Most of the time there either isn't enough gas to explode or the operator got lucky and didn't get killed. Sometimes the operator doesn't get lucky.
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
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RE: Valve, Gas fluid flow question
thank you again.
RE: Valve, Gas fluid flow question
David