Replies

1. 
   Sphere | Jul 12, 2004 02:28am | #1

   most likely..did ya shoot it with a level? or are ya guessin at 8'?

   most SP's are 1/3 HP..not much ooomph there.

     edit to add: ya got 30' of 1 1/4 " hose full of water, plus the 8' of water pushing it back..I smell a pump smoking.

   Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations. 

   
   

   ---

   Edited 7/11/2004 7:30 pm ET by SPHERE

2. 
   DanH | Jul 12, 2004 03:57am | #2

   If the run to the front yard is mostly downhill it won't add much to the pump load. If it's level or uphill then you may have to get someone to work out the math for you.

   I'd say try it (just lay pipe on the surface) and see if it seems to work OK. (Ie, see if the pump seems to be maintaining about the same rate of pumping.)

3. 
   NickNukeEm | Jul 12, 2004 04:14am | #3

   Is there any data on the nameplate of the pump?  i.e., suction lift, pump head, etc.?  Pumps are usually rated at some designed flow at some designed pump head, which takes into account suction head requirements and discharge head (or back pressure from height, system pressure, etc.)

   If you know the pump head data, you can figure out if the pump is designed for what you are planning.  (Thumbrule, 1 foot of height equates to about .434 psi back pressure.)  However, as your length of pipe increases, coupled with any addition of bends, the system in effect creates more backpressure, a term which is called headloss.  The pump has to work harder due to increased resistance to flow.

   Bottom line, if you don't know the data, give it a try anyway.  The worst that can happen is that Sphere with smell the smoking pump, then you can buy one based on the conditions you intend to submit it to.

   Good luck.

   I never met a tool I didn't like!
1. 
   rjw | Jul 12, 2004 05:42am | #4

   >>If you know the pump head data, you can figure out if the pump is designed for what you are planning. (Thumbrule, 1 foot of height equates to about .434 psi back pressure.) However, as your length of pipe increases, coupled with any addition of bends, the system in effect creates more backpressure, a term which is called headloss. The pump has to work harder due to increased resistance to flow.

   That's why I love this place ... The range of expertise is staggering!

   Question: would I be correct in figuring that the dianmeter/ cross section of the pipe has to be figured into that calc?

   E.g.:

   2" dia has 1.36 pounds back pressure

   2.5" has 1.70 pounds back pressure

   3" has 2.05 pounds back pressure

   (A=Pi*Rsquared *.454)?

   "It is as hard for the good to suspect evil, as it is for the bad to suspect good."

   -- Marcus Tullius Cicero, statesman, orator, writer (106-43 BCE)

1. 
   ajm | Jul 12, 2004 05:53am | #5

   pipe diameter has nothing to do with head pressure. actually distance will have very little effect either it is total lift that decides pressure. from suction point to highest point in the piping.

1. 
   rjw | Jul 12, 2004 07:32am | #7

   But if head pressure is measured in PSI, then in figuring out a pump's capacity, don't I have to figure on how many SI's I'm trying to push uphill?

   Or have I sniffed too many sump crocks lately? {G}

   "It is as hard for the good to suspect evil, as it is for the bad to suspect good."

   -- Marcus Tullius Cicero, statesman, orator, writer (106-43 BCE)

1. 
   BillHartmann | Jul 12, 2004 08:38am | #8

   I just found some specs for Red Lion submersible sump pumps.

   The file I downloaded has specs for 2 models.

   1/4 hp

   hd 5ft - 24 pgm

   10ft - 19 gpm

   15 ft - 12 gpm

   20 ft - 3 gpm

   21 ft - 0

   and 1/3 hp

   5ft - 33 gpm

   10ft - 23 gpm

   15ft - 16 gpm

   20ft - 5 gpm

   23ft - 0

   Now that height is total head. That is the amount of vertical lift needed, plus any friction loss in the piping. For low head pumps like this it is given in ft. For higher pressure pumps it is give in psi. In either case you can convert from one to the other with .433 pse/ft.

   Now in this case we have 8ft of basement elevation and then maybe another 8ft to get to the front yard. The orginal question was not clear if this was an additional 8ft elevation or not. And assuming that it did not dip back down on the other end. (If it did you would get that back by shippon as long as it had enough pressure to get the first gallon over the peak).

   So that would give us about 16 gpm. cking the chart for 1.5" sch 40 PVC (from a sprinkler design manual) you get a pressure loss of 0.71/100 ft psi or almost another 2 ft of head. I am guessing that the length is probably 50ft or so or a head loss of less than 1 ft.

   You would need to chart it out and do a couple of iterations to get the real flow rate, but that will give you some idea.

   So that would work, but you are near the end of the curve.

   If the elevation or run was a little more then you would want a larger pump (or different design).

   So if th

2. 
   ajm | Jul 12, 2004 11:05pm | #10

   but all you have to do with regards to extra bends is increase line size and you will reduce friction coefficient enough to almost take anything but lift out of the equation.(i am pretty sure, but check your irrigation chart for 2" pipe to see how that factors.)

3. 
   ajm | Jul 12, 2004 11:01pm | #9

   "But if head pressure is measured in PSI, then in figuring out a pump's capacity, don't I have to figure on how many SI's I'm trying to push uphill?"

   No, SI (square inches, i presume) doesnt affect. youre actually talking about two different things. if you were trying to figure pumps volume (gpm) then you would need to factor velocity and square inches. but PSI is not relative to SI only to depth. psi measure's same at the bottom of a 10" diameter pipe 100' high filled with water as a 10' diameter pipe the same distance filled the same.

2. 
   NickNukeEm | Jul 12, 2004 06:33am | #6

   The static head on a pump in an open system is based on atmospheric pressure alone, whether the pipe size is 1 inch or 100.

   I disagree about the effect of pipe run and bends on a system (horizontal run).  They won't matter much in a vertical position (still open system) however, string your garden hose out a few hundred feet and the pressure at the outlet will be less than at the hose bib.  This is due to the long run, pipe size, and whether the flow is laminar or turbulent.  I forget the thumbrule now, but we used to add 5 or ten feet of run for every 90 or 45 bend.

   The formula for calcuating head loss is:  Hf=(f)(L/D)(v2/2g)

   f is the friction factor, L is the length of pipe, D is the diameter, v2 is the velocity squared of the flow, and g is the gravitational constant

   Bernoullis must always be satisfied.

   Haven't thought of this stuff in years.  Brings back nightmares...

   I never met a tool I didn't like!