4 replies to this topic

[Ankur Shah]

hey!

I am just reading that butane is added to gasoline in winters. how true is this? where is this done? and is volatility the issue here?

Ankur

[abhi_agrawa]

If butane is added to gasoline, it will lower the RVP. This will ensure that during the cold-startup of the vehicle, enough vapor is present for the vehicle to start. I do not know where it is done, but I think that this should be the case in cold countries.

[mbeychok]

Ankur:

(1) Butane addition will increase the gasoline vapor pressure ... not lower it!
(2) All gasoline has some butane in it. In cold weather areas, refiners will blend in additional butane to increase the vapor pressure to make sure that auto engines will start during the cold weather. In the USA, we sometimes refer to "summer grade" and "winter grade" gasolines. Some of our states even have regulations concerning the vapor pressure levels required for summer and winter grades.

[Ankur Shah]

hey!

i got this clarified with a certain person in my dept. he gave a longer answer. he said...

butane is cheap and hence the more of it that can be pumped into gasoline the better. now, gasoline has a particular max Reid Vapour Pressure (RVP) which needs to be maintained. In winters, the RVP of gasoline falls and hence butane is added as its volatility is higher. hence, as far as the rvp is not exceeded, it is fine to add butane.

so i guess the answer to the last question is that it would depend on the place where u are.

can someone from the US tell me if there is a SIGNIFICANT difference in the price of summer and winter gasoline? i cant say with regards to india simply because the prices increase every week here... any comments?

Ankur