Just got an idea. If I hook a tube up to my liquid ball lock post from my actively fermenting beer and on the gas had a spunding valve would that work to pre purge my keg of oxygen? I think @TheBeerery mentioned this before but had the gas side going to a container of sanitized water.
Sorry I forgot to mention I'd have to set the psi of the spunding valve to as low as possible so there wasn't pressure push back.
