Submersible pump inside deep water well

[sowhatso]

If a submersible well pump will be installed inside a deep water well at about 450m depth, SWL=350m , and the pump will stay inside the well for about 1 year without operating , what parts are expected to be effected , I know this pump is designed for water wells but as the pump will not operate and the shaft ,impellers,and all rotating parts will stay static inside the well withno rotation . IS IT OK ???????????

 

[TenPenny]

In the absence of any water contaminant issues, your biggest concern will be the bearings. It is usually recommended, even on above ground pumps, that the shafts be turned occasionally; I would suggest that running the pump every 3 months, for a few hours would be a good idea.

 

[thewellguy]

I agree with tenpenny. Another factor to consider is the agressiveness of the water the pump will be sitting in. How badly with things get corroded during that time. Ehy don't you just wait to install?

 

[sowhatso]

Dear Tenpenny and the wellguy,

Thanks alot ,Regarding the water it is clean water and there is no contamination, if the pump will be installed inside the well for one year with no operating, does that mean that all bearings will be damaged and we have to pullout the pump again ?? this issue is very urgent to me and I need valuable inputs ....

 

[thewellguy]

We can't say if the bearing WILL be damaged. We are saying that it is POSSIBLE that damage will occure and the pump will have to be pulled out again. Again if the pump isn'tgoing to be used for a year or more why install it?

What size pump and equipment it this?

 

[crazytexacan]

GREETINGS: easy one, IF the pump is a name brand, and a FRANKLIN motor what size?? hp. ?? Be sure and grease the coupling internally between the pump and motor, BE certain the motor is VERY well grounded, and BE CERTAIN there is complete electricial disconnect between all power, even the neutral if single, phase, or rust, and water issues are the least of all your future issues.... LIGHTNING is the bear, and a year is a very long time ...

 

[BarryEng]

In our area, we have artesian bores (down to 750 m) that are operated full time for about 4 months of the year (over the summer) & then are left for the rest of the year.

We very rarely have problems (I assume) due to the lack of O2 at that depth. Temp is about 35 deg C & TDS is about 1100 mg/l. The bore has a positive pressure of 30 m at the start of summer falling to about ground level at the end of summer. Over a winter, the pressure goes back to 30 m.

We have quite a few of these bores operating & maintenance is far lower that for a PS that is starting & stopping all the time.

We used to have deep well turbine pumps but the shafting (& bearings) gave us problems & now it is almost standard practice to equip the bores with submersibles.

If there is any interest (from this thread) in the maintenance problems of these bores, I can find out for you.

 

[sowhatso]

Dear BarryEng ,

Thanks alot for your input , I'm realy interested to have some information about the maintenance problem of these bores , I appreciate if you can attach some of the data.

Regards

 

[BarryEng]

I'm civil/struct, not mech, so I have only had an academic interest in the bores. I will try to find out tomorrow from the mech & elec people - it should not take too long.

I'll probably post some info in the next day or two. If you a interested further, I will try to send you the contact info for the utility (I don't - yet - know how to do that in this web site).

 

[BarryEng]

I checked with out with our mech & elec people & they offerred the following: -
Most of our artesian bores are 600 to 700 m deep.
Casing 350 mm GRP.
Sub pumps 250 to 300 dia.
Screens 200 mm dia.
Artesian bores are now sub surface water levels.
>30 m, sub pumps are generally cheaper.

Maintenance problems
In the old days, back spin was a problem but now with reflux valves & operation (do not start a pump within x mins of shutting off), this is not a problem.
It is generally expected that a system would be used for a min of 5 - 7 years before any maintenance was due.
Most maintenance is due to silt & sand causing bearing & impeller wear. This is monitored with SCADA systems that check (daily) for changes in effic of the unit. As effic reduces, then planned maintenance is carried out.
Silt & sand in the aquifer can be a problem. If the bore is fully developed, there is no immediate problem. Problems may develop in the future but we have had no problems in the last 10 years. Most of our bores have a good graded sand sufficient for a potable water use.
Iron is not a problem in the deep bores - but iron bacteria is a problem in the shallow bores.

 

[sowhatso]

BarryEng ,Thanks alot for your help

 

[thewellguy]

I would suggest that the next time out pull one of the pumps you have the well screens cleaned. There are several methods available. Airburst, brushing or chemicals depending on the type of build up on the screens. The cleening of the screen should increase the effeciency of the screen per linear m. This will slow down the water that is traveling through the screen and the slower the water moves the less material it will carry. This should help increase the life of you pumps.