Purging fuel lines. 4

[blacklabs]

Our site requires that we purge fuel lines (natural gas and butane) prior to any maintenance. We do this with N2 at the present time. We have a fairly good supply of CO2 on site. Is there a downside to purging fuel lines with CO2?

 

[turboco1]

You need to check the gas properties of each and determine displacement volumes and rates, etc...the only displacement using CO2 that I'm familiar is using CO2 inbetween air and hydrogen gas/degas operations in hydrogen gas cooled generators. The CO2 is never left as a blanket...

Whe laying up a power piping system it has always been a nitrogen blanket as this is inert...retards corrosion.

 

[abeltio]

CO2 is too heavy, if not done carefully: you may have CO2 sitting at the bottom of the pipe and natural gas sitting on top of it...
the only way to ensure that there are no gas pockets is to use a large amount of CO2 and sample ALL the high point vents to ensure that the CO2 concentration is higher than 97% in volume.
similar to the example cited by turboco1.

also, CO2 is much more expensive than N2... the main reason to use N2.

saludos.
a.

 

[frankiee]

Carbon dioxide - Solid particles of carbon dioxide become charged during discharge from the nozzle and can lead to incendive sparks in a flammable atmosphere [3, 5].

That is from --Static Electric Discharge Hazard On Bulk Oil Tank Vessels


International Safety Guide for Oil Tankers and Terminals (ISGOTT), advises against it but I don't have the manual here to quote from it.

More investigation is recomended before you do it

 

[BSQUAREDBUCKEYE]

In the water industry they use CO2 to lower pH by injecting it in the water. If water is present in the fuel line could it form an acid? Carbonic?? CO2+H2O

 

[blacklabs]

Great stuff everyone! Many thanks!