There are as many LPG compositions as there are LPG producers.
So you best check with the supplier of the LPG. In any case check whether that LPG contains olefins.
Or you can make any mixture of C3's and C4's , plus max 2 mol% C5's, such that the mixture has the required vapor pressure, according to Hysis. But you should realise that there are different mixtures with the same vapor pressure possible, especially if the LPG also contains olefins.
A vapor pressure of 300 kPa at 37.8 oC for LPG seems low to me. Are you sure that is correct? Would be almost pure C4's.
Edited by PingPong, 23 February 2015 - 11:33 AM.