I am trying to install a new system that will be able to pump sewage for a one bathroom mobile home 740' up a slight hill to the city line. The surveying tool showed the top of the hill is 4' 6" higher than where the system will be set up. This means I already lose 4' 6" of head from the hill?

I don't think I understand the head loss equation.

When I factor the pipe friction of 3.03 loss a foot- 740 feet at 40 gallons a minute I loss 22.42 head using 2 inch pipe, but at 125 gallons a minute I would lose 184(24.96 loss a foot?) This makes no sense to me.. So if it moves the sewage to fast it won't make it up the hill?

Most pumps I have found say they have a 2" discharge; also 2" pvc is much cheaper than 3" so I would like to be able to use it.

This also has something to do with the discharge height? For this particular 3/4hp pump I am looking at has 20' for 40 gal/m and a maximum lift of 24'. If I lose 22.42' of head just for the length of pipe, remembering the 4' 6" hill making it a total of 26.92'. I have already maxed out this pump?

1. Do I need a smaller 1/2 hp or a bigger 1 or 2 hp?

2. Can I use 2 inch pipe without a problem based on the pump I get?

Thank you for any help

 

You're posting numbers and the unit you're using is not obvious. What is "3.03 loss a foot"? So, I'm not checking your math. Don't forget to include the fittings including a check valve in your calculations. 90 degree elbows and check valves are killers for flow.

Friction increases with speed. To move the same amount of liquid through a smaller pipe it must go faster which is why your friction losses are less in a larger pipe. You will have to figure the happy medium between more expensive pipe versus the pump's cost.

I would not pick a pump with such a low head pressure as the 24' you mentioned. That sounds like a sump pump or other type of high volume low pressure pump. Not the best for moving liquid great distances. I'd pick a pump with a higher maximum head to give you extra margin for error. The horsepower is less important. It's the pump that matters.

How fast (gpm) you want to get the poo up the hill?

 

3.03 was taken from a chart that shows 'friction head loss feet water/ 100 feet.' Apparently that was for steal pipe, so pvc is listed at 3.47 friction head loss for every 100 feet.

The site is Appendix A: Friction Losses for Water Flow Through Pipe - Construction Dewatering and Groundwater Control - Powers - Wiley Online Library for where I found this chart.

Did I at least have the hill figured right? With is being 4' 6" taller than where the system will be, it loses that in head?

I just want the perfect set up and most people I trying asking information just want to sell me their product. Had I went with what the plumping supply store recommended I would have the pump I mentioned in my previous post.

As for elbow that will be used I believe it will be one. And one check valve. Which is another question, which check valve should I use? I see some that are brass some that are black with clamps. The plumping store recommended a $60 brass swing valve.

 

Are you putting in a pit? Liberty has pits and you can get any pump with them..

My advice is to call liberty, that all I use, and they will tell you what you need...

Plus there are different typed of pumps. ejector, grinders....etc...



Liberty Pumps : Pump Sizing

 

wow thank you. I filled that form out, waiting on a reply now. And yes, or at least I guess we will be putting in a pit. The plumbing store recommended a 18" x 30" basin.

 

Post back when liberty gets back to you. Curious what they say...

They will recommend their pit size also.. One bath you dont need nothing too big pit wise , or too small, that the pump will cycle too much either...


Liberty Pumps : Sewage Pumps / Systems

 

They were very fast with a response and gave two options.

Liberty Pumps : Simplex Packages

And

Liberty Pumps : Grinder Pumps

Before they recommended it they asked if the city line I would be connecting to would be gravity or pressurized. In my case, gravity.

Now just to find a place to order it and have it shipped to home. All their site has is a distributor locator, closest one is nearly 100 miles away

 

How much money you got? I installed two of those grinders a few months ago. The grinder alone is around 2K... Those packages run 6k and up..

You supplying 240 volt or 120v?

Thats all they recommended? Its a bit over kill IMO...

 

did they calculate your head pressure? What was that?

 

When I installed the same pump in pits I ran some 200 plus ft.. I ran 2" copper though.. Thinking about it the 2hp omnivor may be the only pump that can do it as they recommend...

 

I would not pipe at 1 1/4 either. I would use at least 2"... Im not sure they are giving you the best options...

Head per 100 ft of 1 1/4 vaies per gallons per minute.. Lets say 40 gpm.. thats 20.1 x 8. (800 ft) = 160 ft head

2" @ 40 gpm = 2.8...x 8 = 24 ft head..


Maybe I am doing it wrong... dont know... Been a while... Add on fitiings , ells and such...

 

I guess that pump would do 48 gallons per minute thru 2” PVC at 41ft. So I'm guessing that we would need to taper the pipe up from the 1 1/4?

With the price of the pipe we are planning on doing the trench and pipe ourselves to save money. Should I just start looking into a septic system? The few I have asked say they can run $7-10k. That is simply out of the question as of right now.

 

Does this system have a holding tank with a float to activate the pump . . . . or do you envision having the pump activate anytime someone flushes ?

 

as far as I know it would have the float activator.

As of right now I believe I will be looking into having the ground perc before I move forward with anything else.