Shower waste

Anybody care to offer advice I have only one waste pipe and the wash hand basin feeds on to it as well as the shower, when the wash hand basin is released the waste water comes up through the shower outlet, is there any non return valve of 40MM that could be put on the pipe I Think if I put a second standing upright pipe beside the basin waste to take the air pressure it might help Any Ideas ?

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Mod Rupert
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There may be a partial blockage or insufficient fall downstream of the tee causing the backup.
You could consider increasing the pipe size at the tee and downstream to 50mm
Or maybe one of these could help http://www.hepworthplumbing.co.uk/hepwasteprod8.htm

Thanks for that link ,somebody else mentioned that valve but they had mistakenly called it a Hempenstal valve. I think thats the answer to the problem Ill try one anyway and perhaps put in a pressure release pipe as well, My problem is ath the shower waste runs past the sink unit en route to the wall outlet, the sink waste drops vertirtically on to a tee,when the sink waste is release it send the waste in both directions even with a sweep tee, a lot of the gurgling is caused by air pressure hopefully that valve will do the trick, thank you for putting me on the right track. Now to buy one.

Thanks Rupert my computer has a bad habit of sending duplicates and I dont know why.