Not for gas log set up apparently

I tried to hook a 20LB propane tank up to a set of gas logs in my house. wanted to be able to be off grid without the contract of a propane dealer. not sure what the problem is but the pilot will work but not enough to stay lit when the logs ignite. pilot just fizzles out and shuts the system off because of the lack of heat that the pilot supplied to the thermocouple valve. suggestions?

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