Simon
I had a look at the english translation of the german iconexplaination. I think I know what you mean. The translator used an unusual word "valve" for the german "hahne" which means cock.
The icon used is a straigth throughflow cock, which means it has a simplifed casing and a removable handle, not wheel (see picture) and the meaning of straigth is that it is either shut or opened by hand, It is used for double sealing of the pipe, the check valve shut by itshelf.
Tore