Re: Does 90 psi require a pressure reducing valve?
Posted by Sylvan Tieger on May 26, 2004 at 13:37:32:
In response to Re: Does 90 psi require a pressure reducing valve?
: I have 90 psi pressure measured in my basement. According to the town and the water company I dont need a pressure reducing valve at that pressure (I did not think to ask what pressure I would need one).
: I'm somewhat surprised by this because they are pretty particular about sprkinler systems (RPP valves are required as is a yearly test by the water company)

Hello Mike,

When the water pressure exceeds 85 PSI (no flow condition) I install a PRV to maintain 85 PSI or less.

The reason being is hydraulic shock is highly possible with quick closing valves and erosion caused by excessive velocity.

Having direct higher pressure to an outside hydrant is normally OK but in the home in case of a leak your going to be flooded out in a matter of minutes.

For example if you have a 1" diameter pipe with a pressure of 90 PSI and this pipe ruptures you have 82.5 GPM flowing

Your velocity would equal about 33.70 FPS OUTRAGEOUS

You can elevate water almost 208 FEET.

Your hot water heater would most probably have it's T&P relieving as the temperature rises.

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