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Is there an accurate phone app altimeter ?


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#11 DavidGraves


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Posted 20 October 2019 - 06:09 PM

Wouldn't it be easiest just to measure the pressure at the bottom end of the pipe?   



Howdy Rando



Pressure ??? HA HA Ha Ha Ha Ha!!!!!!!!!!!!!!!!!!!!!! ...makes me want to jump in the creek.......we're talking gravity flow here...........I'm heading to the creek........pressure ????????


If the inlet is a stream - just measure the pressure at the outlet with a  faucet pressure gauge.     The elevation change between the two ends of the pipe (in meters) is the pressure (in bar)/0.0981.


Otherwise your iPhone does have a barometric altimeter built in - but I am not sure a barometric altimeter will be any better than an augmented GPS:


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#12 rando


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Posted 20 October 2019 - 06:56 PM

Gravity flow is exactly the answer!


Pressure = density * gravity * height.   Density = 1, gravity = 9.81 


You may need a more sensitive pressure gauge, but if you want to know your (net) head, you measure the pressure at the bottom.    If you have no pressure you either have a leak or no head. 


Something like this should give you a sensitivity to about 0.1M in height:


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#13 ckent323


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Posted 20 October 2019 - 09:53 PM

Interesting topic.  Seems that if you need elevation accuracy to less than +/- about 20 feet then using a smart phone app is not the way to go.  Some smart phones have barometric compensation built in and may be capable of reporting altitude within +/- 10 to 20 feet with appropriate application software.





If you need accuracy to less than 10 - 20 feet then you will need a calibrated and barometric pressure as well as temperature compensated altimeter.


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#14 DavidGraves


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Posted 20 October 2019 - 10:24 PM

Many thanks to All....


This was fun hearing lots of good ideas....


But I need accuracy to within a foot.


I guess the short answer to my query is that there really is no accurate Smart Phone app for altitude.


Maybe we should have a party at my house to work on the pipeline !


Thanks Again.



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#15 smlobx


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Posted 24 October 2019 - 11:38 PM

I believe my Garmin InReach can accurately measure elevation...maybe you could rent one at your local REI?

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#16 DavidGraves


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Posted 25 October 2019 - 12:42 AM



Thanks for that...what accuracy can you get with it.....change between to point visibly different...say three feet ?



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#17 Arctic



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Posted 13 January 2020 - 05:38 PM

What did you wind up doing?

Water can also run uphill.
Ask a roofer.
Capillary action.

Use a level and level rod for elevation changes.
Ask a Surveyor.
Far more accurate than any other method that relies on barametric pressure or GPS and you really need gnats ass measurements for the differences you are calculating.

If you are keeping the same route for the waterline and doing grading, then the inlet pressure should not be effected and the outlet pressure (head pressure) should improve due to less pipe required with fewer ups & downs. Shorter pipe length means less pressure loss from friction inside the line.

Are you upgrading the line? Possibly increase diameter.

Edited by Arctic, 13 January 2020 - 05:48 PM.

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#18 PackRat


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Posted 14 January 2020 - 08:55 PM

David....given that you need to fork out some cash for gizmos you probably won't be using enough to justify their purchase, let me ask a couple simple questions.

1) as long as the source is higher than the end of your service, gravity should work out OK for you, right?

2) if you have enough differential between the source and end of service, gravity will overcome a few blips in altitude along the way, would it not?

3) if you prime the line to remove any air gaps where the blips in altitude are, you should get a decent flow if you have enough differential between source and end of service and if the diameter of the pipe is large enough

4) while the smart phone accuracy may not be enough, couldn't you get a decent altitude at the source and at the end of service using Google mapquest? Again, as long as you know there is a differential, that should work.

5) the problem may be that at some point the pipe comes so close to the altitude of the source that gravity isn't sufficient enough to supply you at the end use location.


If you ever tried to siphon gas into a gas can, you already know that the flow will increase the lower the end you are trying to fill a gas can with and conversely, once you have enough, as you raise the hose, the flow is reduced....until flow stops and air enters the hose as the remaining gas in the hose reverses direction back into the tank.

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#19 ntsqd


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Posted 15 January 2020 - 04:30 AM

Is the distance involved too great to use a fluid filled clear tube? With both ends open to the atmosphere the fluid will be the same height at both ends. Measure to the ground from the fluid level to get the elevation difference.

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