Beijing Airport

does anyone here traveled through Dragon air (international flight) departing from beijing airport, if so please someone tell me how much baggage they will allow?? ((well i saw the official website, it says 20kg as luggage and 5kg by hand for economy class-- but thats not accurate,in airport they usually allows more--may be 30 or 40kg)) If someone traveled by that and you know that for sure please clear my doubt (because i don't want to pay for extra, and wont have anyone with me to take that back in airport-- i heard like beijing airport is bit strict on their rules) Please help (sorry for making the question a bit long..)

thank you