Water flow calculation

avorancher · Apr 9, 2006

Vandals broke a 2" main on my property last night while stealing a stainless steel irrigation filter housing. I guess they were too rushed to turn off the water after breaking the pipes on either side of the filter.

Anyone know how much water I lost during the 8 to 10 hour period so I prepare for next months water bill? It was a 2" schedule 40 pvc pipe with 150lbs. pressure measured within inches of the break.

I know it was a lot of water due to the flooding I discovered this morning, but I can't find a calculator on the web that gives me to the maximum gpm a schedule 40 can carry at that pressure.

JoeR · Apr 9, 2006

The maximum volumetric flow of 2" pipe is about 50GPM. If memory serves me correctly. Depends on the pump. PSI can only be measured in a closed system, so when your pipe is wide open, you have far less pressure. You are looking at upwards of 30,000 gallons. If in fact you were pushing 50GPM.

Bully · Apr 10, 2006

It's 150 psi static pressure. you would have to have some idea of what the pressure would be residual with an open butt 2" pipe probably 15-20 psi. aruond 30-40 gpm ? lots of mud on your feet....Gary

avorancher · Apr 10, 2006

Pump is from regional water company and my 2.5 inch meter is sitting on top a 36 inch main which is only 10 feet or so from the break.

Although bad, 3,000 gal. per hour isn't nearly as bad as I was imagining after looking at the erosion it did. At least I'll be able to lay some culverts in without digging.

Looks like they got my tank plus 2 others on the same road. Can't believe someone would steal a stainless steel cylinder right off the irrigation system. Maybe that explains why new ones are plastic and why ranchers buy guns.

NY_Yankees_Fan · Apr 10, 2006

I have placed a flow meter on 2" pipe at 140 psi and have gotton 400 gpm and that was after a 2" globe valve. If the pipe was 100% open, it was closer to 500 gpm. The average fire hydrant has 2.5" openings. For sure you are in for a BIG water bill. /forums/images/graemlins/mad.gif

RonR · Apr 10, 2006

I'd contact my water company. With a police report, they might discount your bill. I think our company would. It wouldn't hurt to ask. You could offer to pay the higher of the last 3 months bills as a "normal" bill, before the vandalism.

Hope this helps.
ron