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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> 22mm High Temperature Non Return Valve https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1484406003 Message started by Lectrician on Jan 14^th, 2017, 3:00pm

Title: 22mm High Temperature Non Return Valve
Post by Lectrician on Jan 14^th, 2017, 3:00pm

I have a site with several sterilisers installed. They have a 15mm chromed pipe outlet for the waste which is opened once a day, ditching 85°C water. Currently, they all have the 15mm pipe terminating into a 22mm overflow waste non return valve, and these fail regularly. The 22mm overflow pipe leaving the non return valve also overheats and bows.

This is the part:

http://www.plumbcenter.co.uk/product/mcalpine-convalve-in-line-non-return-valve-22mm/

It seems to me that a metal version would be better, to cope with the heat, and 22mm metal pipe, not overflow. The overflow eventually terminates into the 1.5" wastes, and these are not affected by the hot water.

Any ideas on the best way forward?

Title: Re: 22mm High Temperature Non Return Valve
Post by CWatters on Jan 17^th, 2017, 6:59pm

Google can find check valves designed for high temperatures...

http://www.valvesonline.co.uk/manual-valves/check-valves/high-temperature-check-valves.html

Stainless steel..
http://www.valvesonline.co.uk/manual-valves/check-valves/high-temperature-check-valves/high-temperature-check-valve-screwed-bsp.html

Title: Re: 22mm High Temperature Non Return Valve
Post by Lectrician on Jan 19^th, 2017, 6:05pm

I'm not sure they are going to work on the near no pressure of an overflow/drain from a steriliser. 1m head maximum.

Title: Re: 22mm High Temperature Non Return Valve
Post by CWatters on Jan 19^th, 2017, 6:53pm

Presumably you can't use an air gap to prevent back flow because air must not get back in either?

1m head of water is about 1.4psi.

Google found these..

http://www.tamo.co.uk/products/valves-regulators/check-valves

http://www.tamo.co.uk/uploads/products/20100216034318-200series.pdf

Says they can do cracking pressures down to 0.1psi and temperatures up to 288C.

I think in this situation I'd explain the problem to a company like that and let them decide if they can warranty their check valves for the application.

Title: Re: 22mm High Temperature Non Return Valve
Post by thescruff on Mar 17^th, 2017, 10:43am

Hep v° trap should do the job