[labnetwork] C5F8 Usage and handling

[Bill Flounders]

Dan,
We do not presently use these gases.
I have been considering C5F8 as potential etch
replacement if California imposes stringent controls on
select freons due to their very high global warming CO2 equivalent values.
I expect I uncovered the same info you already have.

1. Re C5F8
I found no indication that this gas is flammable.
Praxair, Matheson, Linde and Air Liquide all list LC50 (1hr): 1124ppm
but don't define reference for this info

TGO "Class II" is defined as 200ppm - 3000ppm
CFC "Toxic" Gas is defined as LC50 200ppm - 2000ppm
Gas cabinet is required for TGO "ClassII" or CFC "Toxic".

I would put C5F8 in a gas cabinet.

-----
2. C4F6
definitely flammable but limited and inconsistent toxicity data
A single source cited LC50 667ppm (4 hours, this is usually listed as 1 
hour)

I would consider C4F6 in a gas  cabinet;
I would seek additional info to support a decision either way

-----
3. CH2F2
I found a single LC50 of 520,000ppm (4hour)
and many TWA (8hr) > 1000ppm.
This has been evaluated as a non-ozone depleting refrigerant
for many years with some concerns about its flammability.

I would handle like methane. I would not place in a gas cabinet.

Of course all the usual disclaimers apply -
not the opinion of University of California blah blah blah
this is simply my personal evaluation,
your local AHJ (Authority Having Jurisdiction) makes the call

Good Luck and enjoy the snow,
Bill Flounders
UC Berkeley



Dan Woodie wrote:
> Hello from the white north,
> We are working on adding several of the more unusual fluorocarbon 
> gases to our Oxford 100 tool and we are having a hard time getting 
> clear information on proper handling and storage of some of the gases. 
> Specifically we are looking at adding:
> Difluoromethane (CH2F2)
> Hexafluorobutadiene (C4F6)
> Octofluorocyclopentene (C5F8)
> Unlike the more common fluorocarbons such as CHF3, CF4, C4F8, these 
> are all flammable, and the last two are also listed as toxic. MSDS 
> information on them is also light as they are fairly new materials and 
> most do not have TLV values set yet. Some sources are indicating that 
> the C5F8 does not need to be in a gas cabinet, but a review of the 
> MSDS makes me hesitant to follow that. Is anyone else using this 
> material and if so, how do you handle it? Thanks in advance for your 
> collective wisdom.
> Dan
> Dan Woodie
> Lab Use Manager
> Cornell NanoScale Facility
> 250 Duffield Hall
> Ithaca, NY 14853-2700
> (607)254-4891
>
>
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