"Hemmina - Hemmina". I believe it is a closed system. Re. pictures - I was kind of afraid someone might ask that - I could take some pictures. A check valve - I would say no. A big "THANK YOU" for replying to my post/question. Sorry I didn't respond sooner but I was checking the internet for what a check valve looks like - I was quite sure I did know but wanted to be sure. As for pictures - I'll have to check if they can be posted directly from my hard drive. So far I haven't taken any.