I have only been brewing my own beer a few months I have decided to go from bottles to barrels, I barrelled my beer 3 weeks ago just went to get myself a pint. after a quarter of the pint was in my glass the beer just stopped flowing, I don't have a lid to inject co2 into the barrel to increase the pressure would it be safe to take the lid off and put a co2 injection lid on without harming the beer if I inject co2 instantly? Please advise