P&ID questions

Ok I am still relativaly new to this business and I realize I don't know everything but I am fixing some P&ID's and some of these marks don't seem right. I have already asked some of the other people in the office and most of them seem to be brain dead. Ok so I have a tank and first off it is labled tk-57 instead of t-57 which seemed odd to me but thats how they want it. Well on top of this tank is a valve, it is the 3 arrows pointed at eachother symbol (left, right, and bottom pointing up) with the relief symbol on top. Isn't this a conservation vent (CV)? They have PVRV but I haven't seen these marked like that before so I was wondering if that was right. I was also told these were marked up by a college intern so thats why I question. Another way the are marked which is odd to me is in the instrument bubble the tank number is on top and then the pvrv-01 is on bottom. Anyone have any insite as to why it is done like this or if its all wrong. I have a hard time telling them, hey this isn't right, when i can't really tell them why with good facts. thanks for the help.
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| TK-57 |
|PVRV-01|
\______/
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\ ><
^ sorry this is the best i could do

It messed up the picture. hope ya'll still get the idea though.

ok I hope this works here is a screen shot of what I am talking about

Alright well thanks guys for your input. It turns out so far that these symbols are supposed to be CV conservation vents. They still have a problem with their numbering system though. I guess what was confusing me the most was that they don't follow a standard so it makes it really hard to compare with other drawings. Right now I'm making them pick one way of doing things and then i'll change everything to match. ARUGH! it suprises me the multi million dollar companies can run so unorganized. Once again thaks for your input.