weighted pallet PRValves

We had designed a pressure vessel for 300 lts. The vessel is to be operated at 15 psig pressure which is normal pressure in a typical cooking pressure vessel. My request is where do I find the relationship/correlation for the internal pressure rating to that of the weight of the 'weighted pallet pressure relief valve'. We picked up a 76 gram simple relief valve from the conventional pressure cooker. Now how do we decide the actual weight of the relief valve for a higher pressure process. The vessel is designed for a maximum operating pressure of up to 30 psig.

Thanks for your inputs.