My moms house has what I thing is a breather valve(approx 1" sch 40) about 6" off the floor connected to the washing machine drain. House is about 3 yrs old raised foundation. I've never seen a set up like this before? We only found it because it started spitting water out during the drain cycle. It looks like its been doing it for awhile, but it is very little water (like 1 cup for every 8 -10 washes). What I would like to know is the breather suppose to have a cap on it.
Thanks

This is a vacuum breaker and it might spurt a little when the washer goes into a drain cycle. There is a valve in the unit that opens when there is no pressure coming from the washer. When the washer drains, the valve has to close and usually there is some leakage. Since it is on a washing machine drain hose, there might be some debris in it that is contributing to the problem. You should be able to unscrew the top and clean it out.

Thanxs for the info will unscrew it and find out