The "NSF" I know is the National Sanitation Foundation. Fittings with their certification may be used on automated food processing equipment and for food dispensing equipment. An example is a coke machine. You would want to use NSF certified fittings for any plumbing components where the drink media is in contact, as opposed to say non-approved brass fittings. The bulk majority of NSF fittings are polypropylene if plastic and stainless steel if metal. PVC pipe used for water plumbing service can also carry the designation.
Dale, is there a reason you need the certification? Or are fittings that meet your needs coincidentally marked with the emblem?
What size barbs are you looking for? For vacuum hose (1.5"-2.5") or solution lines (1/4"-1")?