SDS Missing Flammability Limits

[RVAmeche]

Hi guys,

I'm working on a project requiring us to analyze various storage & process vessels to ensure their relief and vent locations are indeed a safe location. While we've received an SDS for all the fluids, most of these datasheets classify the fluid as flammable and then fail to show the flammability limits. This appears to be the norm rather than the exception, and research online hasn't yielded much results. Additionally, the vendors/manufacturer's have frequently come back and said "we don't have that data" which seems pretty surprising to me.

If a material is classified as flammable, are the flammability limits not required to be published? Or why does the vendor/manufacturer not have to be able to provide this information? The same experience applies to the toxicological side as well. I've seen some equations for estimating LFL/UFL in Perry's, but I believe this are based on simple hydrocarbons, which is not what I'm looking at.

Thanks

 

[Latexman]

Required to be published? No. What chemicals you looking for?

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[georgeverghese]

Presume these compounds you need LFL / UFL info on are not in table 26-10 in the 7th edition of Perry?

 

[RVAmeche]

I was just surprised by that, I would've thought that information would be necessary.

Most of what we're looking at are various types of siloxanes. The published data for these chemicals appears to be sparse.

 

[Compositepro]

The information required to be provided in SDS's is the minimum of what is needed to make appropriate decisions about safe handling of a material. If you design your vents to handle "flammable vapors" as defined in the regulations you should not need anything more. If you do need more data for some reason you can only get it from the supplier or test it yourself.

 

[RVAmeche]

Got it. This client has several storage tanks with existing conservation vents/emergency vents and is having dispersion analysis conducted on the vapor release is safe. Since some of the fluids don't seem to have published FLF/UFL data, that makes it difficult. Several suppliers have indicated they don't have the data themselves; when asked how they size the vents on their storage tanks they don't have a response. It's an interesting situation.

 

[Compositepro]

This type of design is based on reasonable worst case assumptions which are given in design codes, and rarely needs very detailed data.

 

[RVAmeche]

What worst case assumptions and code are you referring to? We're using API 2000 and several of these vents appear to be very undersized, especially for fire cases. That's regarding the actual sizing of the vents though; my initial question was regarding the vapor release & flammability. If a code/standard contains worst case assumptions to use for flammability I'd be very interested in that.

 

[Compositepro]

This is not my area of expertise. The National Electric Code (NEC or NFPA 70) explains how to categorize areas. In a fire event none of this applies, since you already have a fire.

 

[RVAmeche]

Yeah I'm aware of NFPA regarding electrical classification of areas, but as far as I'm aware, they don't have any worst case assumptions to make for LFL/UFL in lieu of physical data.

 

[Compositepro]

100% concentration of your most flammable ingredient is the conservative assumption.

 

[jari001]

@Compositepro - Perhaps I don't understand your point about "100% concentration of your most flammable...". Wouldn't that make the vapor space/stream too rich to support combustion (i.e. above the UFL)?

This came up when I googled "flammability of siloxanes", maybe the paper's citation section will turn up something for you. And it's not even behind a paywall to boot!
"Thermal stability and flammability of silicone polymer composites"

http://www.sciencedirect.com/science/article/pii/S0141391005003733

Googled "estimating flammability limits of siloxanes", this paper has the words "silanes/siloxanes" in it but I've forgotten my ACS login so I can't download it
"Chemical Structure-Based Model for Estimation of the Upper Flammability Limit of Pure Compounds"

http://pubs.acs.org/doi/pdf/10.1021/ef100207x

I never really thought siloxanes presented an appreciable fire risk...learn something new.

 

[RVAmeche]

Really? I only see the $40 buy or rent options from the Science Direct link

 

[jari001]

See the attachment for the Science Direct source. I didn't notice that my company's login had kicked in for that.