Nitrocellulose Storage Facility

[gadfly56]

We are designing fire protection for a customer storing solvent wet (IPA, 30% w/w) nitrocellulose (NC) in a building with four (4) rooms separated by 3 hr or better rated walls. These areas would appear to be Class I Div 2 for the IPA since the drums are never opened in the storage areas and the only time you have a release is if a drum is accidently opened (falls, gets crushed, top "garroted" off). NFPA guidlines say treat the solvent wet NC as if it were IPA.

To save money, it's been suggested to run our raceways above the classified area if we can determine how high the area extends. I've looked at NFPA 497, and it looks like we might be OK at 5 feet above the top of drum storage. Ceiling is at about 20 feet and ventilation is probably poor to nil. Vapor density is 2.1. We'd come down with an EY seal to each rated flame detector. I'm just not 100% confident I want to go in this direction. Can someone point me to other resources? The manufacturer is no help: "follow all local codes and regulations" and "have a nice day" .

I'm inclined to tell everyone it's all Class I Div 2, live with it. Other thoughts?

 

[petersonra]

Does it really make all that much difference cost wise? Other than a few extra seals?

In any case, IMO, unless you are being paid to classify the area, you should not be making those decisions.

 

[rbalex]

You didn’t mention the NFPA standard you are using as the guideline. NFPA 35 or 40 is a wild guess, but NFPA 30 is still very likely to apply. That said, the entire room should be Class I, Division 2, Group D. (See Table 515.3, Line “Inside rooms or storage lockers used for the storage of Class I liquids”)

It will make little difference; in fact, it may even save a few boundary seals. Also See Section 517.7.

 

[gadfly56]

You didn?t mention the NFPA standard you are using as the guideline. NFPA 35 or 40 is a wild guess, but NFPA 30 is still very likely to apply. That said, the entire room should be Class I, Division 2, Group D. (See Table 515.3, Line ?Inside rooms or storage lockers used for the storage of Class I liquids?)

It will make little difference; in fact, it may even save a few boundary seals. Also See Section 517.7.

Thanks, it looks like I can at least make a case for whole-room classification. I was trying to go by NFPA 35; section 8 is all about NC but didn't say anything about hazard classification for electrical purposes. I think I'll play it safe. If I burn too many more engineering hours on this, I'll have made the difference in cost and have nothing to show for it!

 

[james_mcquade]

One important thing you must consider, if your system is over the drums and one drum goes up in flames,
you will get a chain reaction. Nitrocelluous burns very fast and very hot as well. will your system survise the heat?

regards,
james

 

[gadfly56]

One important thing you must consider, if your system is over the drums and one drum goes up in flames,
you will get a chain reaction. Nitrocelluous burns very fast and very hot as well. will your system survise the heat?

regards,
james

This will activate a deluge system. All it has to survive for is the first alarm, after that it's "build-an-Ark" time!

On that note, though, I think I'll see if I can use separate DLC zones, just in case.

 

[G._S._Ohm]

One important thing you must consider, if your system is over the drums and one drum goes up in flames,
you will get a chain reaction. Nitrocelluous burns very fast and very hot as well. will your system survise the heat?

regards,
james

Here's a tidbit from a guy who made atom bombs.
If the burning rate increases with time it is properly classified as 'an explosion'.