R600a calculation

I need a boffin or techy.
Theroretical but I would like to find the answer ,if there was a leak (say 100rms) it vapourises/expands,then mixes with air,it needs approx 1 part isobutane vapour to 9 parts air for flammability, so the 100 grams expands as a voupour mixes with air at a rate of 1 to 10,:
Wondered what would be the cubic size of this complete mixture would be.
So if 100 gram leak takes place in a room 10 meters x 5 meters would it fill it (as a flammable mixture) over flow from the room
Any help would be of great interest.

Gas Data
Atomic Weight	58.124
Boiling Temp.	-12
Vapour Pressure (psia) @ 15°	38
Critical Temp. (°C)	135
Cond. Temp. at 26 bar abs (°C)	114

I am sure I have worked this out in the past but sadly the grey matter is slowly turning to sludge.
I know he explosion/flammable limits are between 1.5% and 15%approx mixture with air
Thanks
BG

Sorry ,meant to put this in refrigerants, if a mold would like to move it please.
Like I said grey matter and sludge :)

I can not answer your question directly but I know that hydrocarbons can be flammable at as lo as 0.2%

Thanks to National refigerants:
SPECIFIC GRAVITY (H2O=1.00):
0.564
BOILING RANGE:
10.9 Deg. F
PRESENT VOLATILE BY VOLUME:
100%
VAPOR PRESSURE @ 70 Deg. F:
31 psig
VAPOR DENSITY (air = 1.00):
2.006
EVAPORATION RATE:
> 1 (Ethyl Ether = 1.0)

FLAMMABLE PROPERTIES

FLASH POINT (METHOD):
-117 F (Open Cup)

UPPER EXPLOSIVE LIMIT (vol.) gas in air):
8.4%

LOWER EXPLOSIVE LIMIT (vol.) gas in air):
1.8%

This might help someone,possibly connected to the 31psi to condense to liquid.

All the way back to Charle's, Boyle's, Avagadro's, Stochiometrics and well a few others.

molecular weight of Isobutane 58.12. so 100 grams is 100/58.12=1.72 gm-Moles; its density at STP is 2.6 kg/m^3. So your 100 Grams occupies More or Less 0.038 m^3. This represents about 6 Bic Lighters....

The lower explosive limit says you need a space smaller than 100/1.8*0.038+0.0308=2.14 m^3 for there to be a combustible mixture, as long as the Air and the ISO are well mixed. Or your 10 by 5 meter room would need to be less than 5 cm high.....Put another way: To reach the LFL in a room 10 by 5 by 4 meters, you need almost 9.5 Kg of Isobutane.

Excellent and informative explanatiion,many thanks.
It's about getting a perspective on the amount needed to cause a problem,very helpful.

Sorry my .2 was a missunderead 2 %