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Flame Arrestor Requirement For Diesel Day Tank


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#1 kumarss

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Posted 31 March 2015 - 02:06 AM

Dear All,

 

I am designing a Diesel Day Tank of capacity 30m3. its a horizontal cylindrical tank at a elevation of 4.5 m outside the engine hall. I have provided this tank with flame arrestor with breather valve. 

 

Pls confirm us whether  flame arrestor is required for this tank or normal goose neck is enough.

 

Ambient temperature outside the engine hall shall be 55°C.

 

Tank Dimension 13.25 m Dia and 8 m T-T

 

Thanks in advance for your reply.

 

Regards

Naveen Kumar T



#2 ankur2061

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Posted 31 March 2015 - 03:59 AM

Naveen,

 

Flame Arrester should be provided for any hydrocarbon storage tank which has a flashpoint of less than 60°C or where the storage temperature exceeds the flash point of the stored hydrocarbon.

 

Refer the link below:

 

http://www.hemmingfi..._arresters.html

 

These days vendors provide a combination of flame arrester and breather valve.

 

Regards,

Ankur.



#3 Zauberberg

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Posted 31 March 2015 - 04:22 AM

I don't think you need a flame arrester in this service but you may need to dig deeper into local regulations and see if this requirement has been set anywhere in the local codes. This really varies from place to place (see the links below - these are quite different recommendations).

 

If the maximum ambient temperature is below the flash point of Diesel, then there is not even a theoretical possibility of back-flash ignition. What is the likelihood that Diesel tank may catch a backfire? Under which scenarios?

 

Flame arresters must be able to be cleaned so they will not adversely affect/restrict breathing of a fuel tank. Some company standards I looked into strictly prohibit the use of flame arresters on diesel/fuel tank venting connections.

 

http://www.co.merced...equirements.pdf

http://www.standard....935/z-015r3.pdf

http://www.earthsafe...-tank-vent-equi



#4 ankur2061

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Posted 31 March 2015 - 05:14 AM

What is the likelihood that Diesel tank may catch a backfire? Under which scenarios?

 

 

Flashback can happen due to any of the following reasons:

1. Electrostatic Discharge e.g. Lightning

2. External hot work e.g. maintenance

3. Failure of external electrical systems e.g. lights, instruments

4. Portable electrical / electronic device e.g. mobile phone

5. Impact Spark due to metal-to-metal spark e.g. falling metallic tools

 

The likelihood or frequency of such an event becomes the subject of a QRA study. If it is established by the QRA that the risk is tolerable then it may not require installation of a flame arrester.

 

However, providing a flame arrester makes it a moot point for discussion during a QRA study.

 

Regards,

Ankur.



#5 Zauberberg

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Posted 31 March 2015 - 07:00 AM

I agree with all the points from above - given that flammable mixture exists inside the Diesel tank. For ambient temperatures less than the Diesel flash point, backfire would not occur no matter what.

 

OP: you can also route the vent piping to a safe location, and avoid all the hassle with flame arresters. Otherwise you need to make sure they never get clogged/restrict the vent flow.



#6 fallah

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Posted 31 March 2015 - 09:46 AM

kumarss,

 

Suppose the tank is atmospheric...

 

If the flash point of Diesel Oil is less than 55 C; then you need to consider the flame arrestor for mentioned day tank, say in your case, in combination with breather valve.

 

If the tank has equipped with a breather valve, it's probable that blanketed with an inert gas; if so, then you can't apply normal goose neck as a sort of free vent on the tank...


Edited by fallah, 31 March 2015 - 09:47 AM.


#7 kumarss

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Posted 01 April 2015 - 04:24 AM

Thanks to ankur, fallah and all for the kind reply.

 

Provided tank is atmospheric tank and the vent open to atmospheric. 

 

Rgds

Naveen

 



#8 fallah

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Posted 01 April 2015 - 04:31 AM

kumarss,

 

Breather valve and open vent, both at top of an atmospheric tank...! Please let's have your clarification on this matter...



#9 victorafisher

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Posted 01 April 2015 - 11:46 AM

Gentlemen:

Here in the US, one governing standard for the flammable and combustible liquid storage is the National Fire Protection Association Standard 30, "Flammable and Combustible Liquids Code".

 

As I recall, there is no need for "Flame Arrester" or flash back arresting device on the normal vent for a diesel tank (a Combustible Liquid II per the International / California Fire Code).  And this was echoed in NFPA 30.  That being said, there are separation distance requirements for the tank vent (normal) from the tank and from sources of ignition.  A simple pressure/vacuum vent is not equivalent to a flash back arrester.  Many suppliers (I've used Morrison Brothers) have combination units (P/V and flame arrester).

 

All that being said, in the elevated temperature environment you mention, an end of pipe flash back arrestor on the normal (pressure / vacuum) vent would be prudent. 

 

The API 2000 document describes vent sizing calculations. 

 

 

Art Fisher

California

Amec Foster Wheeler






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