Yeah. Damn right it does, too. It also depends on the temperature. Giz another blanket, Guvnor? It's bleedin' freezin' today! <Sneeze, dribble, splutter, cough>
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Essex jobs for Essex yobs! <Burp>.
If your SF6 insulated switchgear is leaking that much I would suggest replacing it.
As others have said it depends on the tank size (amount of SF6 gas) and original tank pressure (there is no direct correlation between psi drop only and pounds of gas lost).