4-way valve at cross connection?

[sjohns4]

I've got a new sludge press which requires a wash water connection. Normally the press will use the plant's non-potable water supply. However, I've also provided a potable water connection should the non-potable supply fail due to pumps, plant upset, etc. I have an RPZ installed on the potable side of the connection. I was told I need a "4-way valve" which will only allow one feed or the other to be connected to the press.

I'm not arguing this is a bad idea at all, but the plumber who is telling me this dosnt know where in the code it says it's required, and for my own info I'd like to know where I can find it in print. Anyone know?

Thanks,

Mike

 

[bimr]

It sounds like your plumber does not know what he is talking about! Never heard of anyone using a 4 way valve in a treatment plant. I doubt it would meet the requirements of any plumbing code either.

What you should install is a break tank with an air gap.

Many states require a break tank arrangement:

http://books.google.com/books?id=mj...m=3&sqi=2&ved=0CCUQ6AEwAg#v=onepage&q&f=false

Here it is listed in the Ten States Standards:

"Where a potable water supply is to be used for any purpose in a plant other than those listed in Paragraph 56.22, a break tank, pressure pump, and pressure tank shall be provided. Water shall be discharged to the tank through an air gap at least 6 inches (150 mm) above the maximum flood line or the spill line of the tank, whichever is higher."

http://10statesstandards.com/wastewaterstandards.html

A break tank is basically a small storage tank with transfer pump. Potable water or recycled water enter the tank from above and each tank inlet has air gaps to prevent back flow.

 

[bimr]

Here is a document from the International Association of Plumbing and Mechanical Officials. In Section 10.10, a 4-way valve is listed as being a cross connection. Cross connections are prohibited by all plumbing codes.

The correct equipment for this application in a wastewater treatment plant is a break tank as previously discussed.