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How do you size a sump pump and sump pit for drain that is used intermittently. I have 6 floor driains in a garage that terminate into a sump pit with a 4" header. Any ideas on what criterea to use to size the pump and the vent?
 

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How did you get this? I am proposing a 1/4 HP sump pump right now, and I was asked to justify.
Pipe size to the third power

Or you could use the old rule of thumb of 5hp for 1" pipe and double the power for each jump in pipe size, but over the years we have found that to be lacking. You see going up 1" in pipe size is not simply double the volume as it is pretty much an exponential equation. It's because pi is 3.14~ not 2.

So basically
3hp for 1" drain pipe
8hp for 2" drain pipe
27hp for 3" drain pipe
64hp for 4" drain pipe

If this is an area like a garage or a workshop you'll want a pump with a ceramic impeller to deal with the extra sediment, a standard bronze might suffice but a cast or god forbid plastic impeller will just grind itself into dust or mush.
 

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Which tristate area do you live in? there are many tristate areas.
 
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How do you size a sump pump and sump pit for drain that is used intermittently. I have 6 floor driains in a garage that terminate into a sump pit with a 4" header. Any ideas on what criterea to use to size the pump and the vent?
I got you bro

Step 1) Read this
http://www.plumbingzone.com/showthread.php?t=11368

Step 2) Might want to read up on head, DFU's, developed length, then that'll determine your electrical, trenching, VTR, although I do agree with the sizing theories already discussed here

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Discussion Starter #12
I am a Mechanical Engineer with 5 years of experience, and I had never done plumbing before. I get the basics of piping, pumps, etc. but I have no experience when it comes plumbing best practices.
 

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The reps or engineers for the pump mfrs are great resources. I always use duplex systems. I prefer factory pre-assembled. Liberty makes very nice products.


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Engineers and doctors.... they always know more than you about fixing their ****.
Your statement is truth. Had a guy call me out to bid on rolling gas pipe underground for a few things in his back yard. When I got there he proceeded to tell me he was an engineer, and this is how you size gas, and this is how it's supposed to be installed, etc. I just laughed inside, cause he was wrong on almost everything. Just enough knowledge to be dangerous. I gave him a ridiculous bid and left. I never heard back from him.👻
 

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Your statement is truth. Had a guy call me out to bid on rolling gas pipe underground for a few things in his back yard. When I got there he proceeded to tell me he was an engineer, and this is how you size gas, and this is how it's supposed to be installed, etc. I just laughed inside, cause he was wrong on almost everything. Just enough knowledge to be dangerous. I gave him a ridiculous bid and left. I never heard back from him.
You did good my friend. You did good

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