unknown tube on commercial toilet

[mistersw]

I have an older Sloan Royal flush 2 that has a tube coming from the vent and into the wall. Not familiar with the application as it looks like it was an add-on. Factory valves don't show such a thing. The valve needs replaced and I am not sure what to do with this tube. Help!

 

[johnjh2o]

It looks like a homemade trap primer.

 

[plumb_bob_square_pants]

This is a trap primer. There should be a floor drain right close by. If there is flush the toilet and you will here the drain gurgle. You can buy these. We use them at the college here in my area. They make them for sinks as well that is very similar.