Thanks!
I found a chart that relates pipe size/volume:
GPM/GPH Flow based on PVC Pipe Size, ie, How much water can flow through Sch 40 Pvc Pipe Size 1/2" 3/4" 1" 1.5" 2" 2.5" 3" 4" 6"
According to the chart, it looks like given ideal conditions a short 3/4" outlet pipe (rated 36gpm max, 23gpm preferred) would pass the full output of the well pump - whatever that is. Then size up from there considering friction loss due to length and fittings. So I don't need to go back to the 1.5" size that I'm replacing. Maybe 1.25" for the longer runs, so a big Rainbird sprinkler can have good volume out at the end of the line.
The chart linked above also references a
chart for length/loss that indicates the Rainbird 100 ft out would receive 10~20 psi less than at the well. This seems acceptable.
I like the idea of trenching with a ripper or potato plow. But where I need to make the first repairs, only my backhoe's boom can fit in there.
*arghs* i hate charts like that. they can easily mis lead someone to getting to small or to large of a pipe. "been there done that" it doesn't matter of pool, pond, well, or other, i simply hate charts found on the internet.
old calc i did up years back. to ball park things out for ponds for pipe sizing.
WorldWide Koi Club - Pipe Sizing ( advance velocity ) calc
entering in first 3 boxes...
50
50
200
entering in next row of boxes.
0.50, 0.75, 1.0, 1.25, 1.5, 2
clicking "calc" button
green P = pressurized flow of water. (example water coming from well pump)
green G = gravity flow of water. you pump water up to some tank up high on a hill. and letting water just empty out of a tank some place down the hill without use of a pump between tank and outlet for the water.
very bottom you can adjust min/max settings for P and G in how they show up for "green" in the chart.
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1" to 1.5" pipe size is what i would be looking at. based purely on velocity alone and inside diameter of pipes and fittings.
to figure things out better. it normally takes an excel sheet, and knowing all the lengths of hose and pipes, and were each fitting and type of fitting it is and the "actual" inside diameter of pipe/hose and/or fittings. we say 3/4" or 1" etc.. but actual inside diameter is less on pvc pipe, and can be mis leading on hoses pending if you look at outside daimeter vs inside diameter of the pipe. then calculating at different GPM (gallons per minute) or hour. and plotting results on the "pumps performance curve chart" to get a more accurate estimated flow rate you would get at any given outlet (faucet or like)
a pumps performance curve... the more the pump has to overcome in friction loss. the less GPM it will produce overall. the less friction loss a pump has to overcome the more GPM it will produce.
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it has been way to long since i had to figure the math out. and done forget, water hammering velocity, i think you want to stay below 15 feet per second, or is it 8 or 9 feet per second (F/S)
i want to say you want to stay above 4 feet per second velocity, to clear any sort of air bubbles that may happen within a line. or is it 7 feet per second?
ya don't take above numbers as fact. "memory is trashed" on all the fine detail specifics.
