Dennerle CO2 check valve problems?

[Delphinus]

Does anyone use one of these? I think they're probably intended more for FW planted setups but I thought I'd try one on my calcium reactor.

Anyhow it appears blocked. With all my might I can't blow any air through it in either direction. Is there some kind of magical "CO2 only" properties to it (I doubt it but I thought I'd ask nonetheless). Or what kind of pressure does it need to open? I don't want to set my CO2 tank at anything higher than 15-20 psi.

The only documentation I can find online is this
http://dennerle.co.uk/Gebrauchsanlei..._Profi_500.pdf

Where I see it says something to the effect the operating pressure for the check valve is 36 bar, well if 1 psi = 0.0689475729 bar, doesn't that mean it has to be run at .. um .. 522 psi ??? No, something's not adding up here. What am I overlooking?