Devise I have never seen before

I was told this is called a Master Cylinder and that it acts as sort of a automatic check valve for when the sewer system from the city backs up and it has a motor which cuts on to pump the water back the other way.

Never heard of this .
Anyone familiar with it?

I assume it is some sort of backflow device and please excuse the title mis-spell

Yes it keeps sewage from coming into the home in case of backup outside. I’ve yet to see one of these at an inspection.

Thanks ,I am not sure about how they work but it is old and I would think a battery backup is needed.

Is it a pump or is it a shutoff valve (controlled by motor triggered by flowswitch)? If there’s a backup from the sewer, I can’t see how the pump is going to force it down that pipe if there’s blockage. Or will it pump it down another egress?


This device is an Illinois thing.

Does it require replacement?!
I use to have one of those failure prediction lists around here someplace! '-)

Bob would this system be on a pump? If so would the pump not have a check valve.
Is it for sanitary or storm?