[VAC] Re: Plumbing vent

[NotoriousBuz@xxxxxxx]

I haven't checked my messages for a couple of days so if this is repeat 
sorry.  Besides the vent being necessary for the venting of gasses, they also 
perform another vital function. If tanks or drain lines are not vented 
properly when draining, they will draw a vacuum. For example if you are 
emptying the gray tank without a vent, the traps in the sinks and shower will 
be sucked out. If you do not have one on the black tank and pull the 
discharge valve it would be like turning a full catsup bottle upside down and 
waiting for the first drop. 

J.L.Dietz #4361