Expansion tank mounting.

I have 3 Apts in my building, thus 3 boilers in my basement. All 3 boilers have the tank mounted upside down, as in the picture below. All I can find is conflicting advice, is this OK or not? Some say you should never mount one like this, others say it is fine, as long as it is supported. it originally had an Extrol #15, and it was replaced once already. I believe it was under sized to begin with, and I am replacing it with a #30. The #15 documentation didn't explicitly say you couldn't mount it this way, but the #30 docs say to only mount it right side up. I have been told I can safely ignore this and others say No. So, opinions or comments? Also, if you would flip it, how would you pipe it? Would you add a air separator? Etc... Thanks! Image may be NSFW.
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