non return valve

[dustnbones]

I've had a non return vavle fitted to the pipe coming off the u bend pipe under the sink. This valve is connected to the washing machine hose. When thw waste from the sink flows out, and passes the non return valve, is there any chance the waste could flow into the washing machine on its way out?

 

[kevplumb]

lift the wmc waste pipe up in an inverted loop

 

[dustnbones]

Thanks kevplumb but what I'm trying to say is, does the non return valve have any sort of block that would stop the sink waste entering the washing machine hose rather than making a loop.