Need help identifying backwater valve

Valve is from a house that was built mid 70s. Need help identifying brand and if still around. Thank you in advance

 

Have you checked with your company service dept?

 

https://www.mifab.com/products/backwater-valve-with-pvc-flapper/

this is my first thought

 

My first thought is this guy is a collector.

My second and third thoughts were that his basement flooded and ....

 

I got some water in the basement, the plumber went through the valve and the flapper was corroded but cleared the main drain

 

Flapper type sewage check valves are nearly guaranteed to leak. These are sometimes called normally closed. Debris will hold the flapper open after a while.

There is a better type called a normally open backwater valve that only closed in backup situations.

The gold standard in sewer backup protection is overhead sewers. Yes, it costs. There is another system that puts a pit in the yard. That pit has a normally open backwater valve, and a sump pump. The sump pump outputs injects downstream of the backwater valve.