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# Conversion Of Nm3/hr Of Air To Nm3/hr Of Blanketing Gas

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### #1 123sm

123sm

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Posted 28 September 2009 - 07:31 AM

Hi,
Just want to know what is best practice in reporting the blanketing gas demand fig.among the following:

1) Calculate Nm3/hr of Air per API 2000 based on the liquid movement in the tank and reporting the same (i.e Nm3/hr of Air ) without correcting it for type of blanketing gas used. (i.e.demand fig. will be same irrespective of type of blanketing gas used)
2) Calculate Nm3/hr of air per API 2000 based on liquid movement in the tank and then reporting the value after correcting for type of blanketing gas used.(as used by Enardo;in line with Enardo euqation concept)

As most of you have definitely worked earlier on blanketing gas in tank farm,hence hope to get satisfactory reply for commonly used practice regarding reporting (whether (1) or (2)) of the above.

### #2 demank

demank

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Posted 28 September 2009 - 11:50 PM

Hi,
Just want to know what is best practice in reporting the blanketing gas demand fig.among the following:

1) Calculate Nm3/hr of Air per API 2000 based on the liquid movement in the tank and reporting the same (i.e Nm3/hr of Air ) without correcting it for type of blanketing gas used. (i.e.demand fig. will be same irrespective of type of blanketing gas used)
2) Calculate Nm3/hr of air per API 2000 based on liquid movement in the tank and then reporting the value after correcting for type of blanketing gas used.(as used by Enardo;in line with Enardo euqation concept)

As most of you have definitely worked earlier on blanketing gas in tank farm,hence hope to get satisfactory reply for commonly used practice regarding reporting (whether (1) or (2)) of the above.

I think we should use the point (2). although the volume replacing the liquid movement out is the same, but the consumption of the blanketing gas from source may different with the different molecular weigth and temperature/pressure.

### #3 Dacs

Dacs

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Posted 06 October 2009 - 09:18 PM

Hi,
Just want to know what is best practice in reporting the blanketing gas demand fig.among the following:

1) Calculate Nm3/hr of Air per API 2000 based on the liquid movement in the tank and reporting the same (i.e Nm3/hr of Air ) without correcting it for type of blanketing gas used. (i.e.demand fig. will be same irrespective of type of blanketing gas used)
2) Calculate Nm3/hr of air per API 2000 based on liquid movement in the tank and then reporting the value after correcting for type of blanketing gas used.(as used by Enardo;in line with Enardo euqation concept)

As most of you have definitely worked earlier on blanketing gas in tank farm,hence hope to get satisfactory reply for commonly used practice regarding reporting (whether (1) or (2)) of the above.

The reported Nm3/hr (Metric) in the standard is not actually a measure of volume, but of moles.

I think that mole wise, you can use the values presented in API. It's up to the engineer to convert it with considerataion of the blanketing source operating conditions/properties.

I've used this philosophy to establish my N2 requirements in my project that I'm handling at the moment. In my case, this is warranted since N2 and air have almost similar MW.

But if your blanketing agent differs in MW w/ respect to air, then I guess you have to compensate for the specific volume of the blanketing agent. But IMHO it won't differ much since we're talking about conditions that we can assume ideal gas behavior.

My 2 cents