4-way valve at cross connection?
4-way valve at cross connection?
(OP)
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
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





RE: 4-way valve at cross connection?
What you should install is a break tank with an air gap.
Many states require a break tank arrangement:
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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."
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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.
RE: 4-way valve at cross connection?
The correct equipment for this application in a wastewater treatment plant is a break tank as previously discussed.