Hanging multiple PEX lines along steel I-beam

I have an I-beam running along the middle of my house's basement, and I would like to attach three 1/2" PEX lines (for hot, cold, and unsoftened water) to the beam, and run them from one end to the other.

Here is a picture of the beam (beyond the wall is a finished room in the basement):

I'm having trouble finding hardware to attach multiple PEX lines to a metal beam. One PEX manufacturer has an installation manual which says that when running PEX along an I-beam, to attach the line(s) to the bottom of the beam, but there's no explanation of how to attach them, or why it would be important to put the lines on the bottom edge (I'd rather attach them to the top edge so they hang on one side of the beam and don't reduce ceiling height). I'm also able to find small C-clamps intended to hold conduit, but that would only work for one line, and I'm unsure if they'll cause friction on the PEX. What information or hardware am I missing?