Vented loop between head and holding tank ?

[Bob 04 H260]

A friend just asked me about using a vented loop in the head discharge hose going to the holding tank. He saw this suggested in the Raritan manual. I had a look, http://raritaneng.com/wp-content/uploads/2016/03/L04v1215PHIIPHEIIOM.pdf
And yes they do show that in their manual. I would have thought "material" would be pumped up into the vent in the loop ? And the vent would have to have a hose going outside so the holding tank would be vented into the cabin. I'm not sure if this is a misprint or I just don't understand the way it might work. Has anyone actually tried this ?
Bob

 

[kloudie1]

The vent of the vented loop is a one way valve that lets air in but nothing out when it is working correctly. A loop between head and holding tank is not necessary unless there is a Y valve that allows the head to also go directly overboard.

 

[Peggie Hall HeadMistress]

The vent of the vented loop is a one way valve that lets air in but nothing out when it is working correctly. A loop between head and holding tank is not necessary unless there is a Y valve that allows the head to also go directly overboard.