Calculating Pump Water Output.

[Crossy]

ALL jet pumps need the jet in the aquifer if you want them to lift more than 8m or so, that's just high-school physics.

 

The local farmers didn't study high school physics.

 

Both you and the farmers would have a more efficient set up with a conventional centrifugal pump with a double check valve at the bottom of the bore (in case one gets some sand in the seat).

[Fruit Trader]

2 minutes ago, grollies said:

A basic house pump needs a flooded suction, I.e. a tank to gravity feed the house pump.

 

I have 2 boreholes, one with a submersible pump, one with a pump similar to Carlyai's and a similar water table depth at 8m.

 

A house pump for boreholes is not recommended.

There is a ITC house pump on a 3 inch bore in our yard that supplies thousands of litres per day to our cleaning shed.  The bore is down 10M, the 1 inch suction pipe and foot valve is down at about 8M and water table  varies from 2M to 6M over the year. Its extremely reliable. The pumps prime is held by the bore foot valve. There are house pumps on shallow wells all over Asia.

[xtrnuno41]

29 minutes ago, Crossy said:

Sorry, I don't understand. A submersible isn't a jet pump and can lift far deeper bores than either a conventional or jet pump.

 

Our OP has a jet pump with the jet / venturi above ground, no advantage over a conventional well pump (actually less efficient).

 

you have pumps with a rotor + blades on it (jet pump) or with pistons. Ill leave out the peristaltic pump as this will be a dosing pump and not used in normal ways. 

You ll have them just up with a suction pipe down or submersible, then it is down in the water.

Never the less the suction pipe and housing should be filled with water then, as a jet pump cant suck up the water by itself, if it s not filled

[grollies]

7 minutes ago, carlyai said:

Right, starting to get it. So regardless of the total head, and suction lift (as my specs are well within this range), I go for the middle of the curve rating and about 12 l/m. So if I got around that (as in 9 l/m etc, I should be happy?

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With the type of pump we have there is minimal suction lift as water is pumped down the annulus to provide a 'flooded suction' to the pump.

 

The principle is the same as underground salt cavity storage of petroleum products where brine is pumped into the cavity, via a twin pipe, pumping down one pipe to move product up the other and force product to the wellhead. These cavities are typically 300m deep but only around 2 bar brine pressure at the surface is needed at the wellhead to move product up 300m. Static head and all that.

[Crossy]

2 minutes ago, xtrnuno41 said:

rotor + blades on it (jet pump)

That is not a jet pump! You are describing a centrifugal pump (which submersibles are too, often multi-stage if you need large lifts).

 

A jet pump has a venturi at the bottom of the bore which feeds some of the output water back down and allows it to surpass the normal suction limit of about 8m.

 

[grollies]

3 minutes ago, Fruit Trader said:

There is a ITC house pump on a 3 inch bore in our yard that supplies thousands of litres per day to our cleaning shed.  The bore is down 10M, the 1 inch suction pipe and foot valve is down at about 8M and water table  varies from 2M to 6M over the year. Its extremely reliable. The pumps prime is held by the bore foot valve. There are house pumps on shallow wells all over Asia.

I agree with you that if the lift is only a couple of metres, a house pump will suffice. I must say that, for that suction lift, I've not seen farmers using (say Mitsubishi) house pumps due to cost, a 2" centrifugal pump is cheaper and as, if not more efficient.

 

But most boreholes will typically have a submersible or jet pump as the op describes.

[xtrnuno41]

8 minutes ago, Crossy said:

That is not a jet pump! You are describing a centrifugal pump (which submersibles are too, often multi-stage if you need large lifts).

 

A jet pump has a venturi at the bottom of the bore which feeds some of the output water back down and allows it to surpass the normal suction limit of about 8m.

 

I do see they mention also such pumps with a venturi, but to use it for water pumping? you pump water through a venturi to create under pressure to suck in the water then. Would be nice for a mixing pump or create vacuum in which the venturi is mostly used for but for water pumping out of a well? To me it would be wasting power to first create a vacuum to suck the water in. As a rotor with blades should first create the waterflow to the venturi to get vacuum and then can have suction. Wouldnt be my kind of pump, as  a water pump.

[Fruit Trader]

4 minutes ago, grollies said:

I agree with you that if the lift is only a couple of metres, a house pump will suffice. I must say that, for that suction lift, I've not seen farmers using (say Mitsubishi) house pumps due to cost, a 2" centrifugal pump is cheaper and as, if not more efficient.

 

But most boreholes will typically have a submersible or jet pump as the op describes.

I know to an other house pump on hand dug ring well that lifts from 7M without problems. The pump delivery exceed the wells recovery and the owner runs right on the limit.

 

[grollies]

35 minutes ago, carlyai said:

 

This thread is great. I stopped posting on TVF, cause I am busy but also after being accused of bullshitting.

 

I pumped water for 25 years extracting from rivers to flood millions of gallons of water into cross-country pipelines for pre-commissioning projects all over the world. FJ is correct, manufacturers of pumps will give you an average, even with the pump curves indicating better performance.

 

I quite often read absolute rubbish on pump systems on TVF but can no longer be bothered at argue the toss.

 

 

[grollies]

14 minutes ago, Fruit Trader said:

I know to an other house pump on hand dug ring well that lifts from 7M without problems. The pump delivery exceed the wells recovery and the owner runs right on the limit.

 

Good for him. My point is that a 1" house pump retails for around B6,000 new. A 2" centrifugal pump can be had for around B3,000 new. If you have a spare house pump, fair enough, I'm not arguing with you about lift.

 

But on a borehole with a water table at 8m, during a drought the water table may drop below 9m in which case a house pump or centrifugal pump is useless, hence why boreholes are serviced by submersible pumps or jet pumps. Cheers fella.

Edited April 21, 2018 by grollies

[Fruit Trader]

2 minutes ago, grollies said:

 

This thread is great. I stopped posting on TVF, cause I am busy but also after being accused of bullshitting.

 

I pumped water for 25 years extracting from rivers to flood millions of gallons of water into cross-country pipelines for pre-commissioning projects all over the world. FJ is correct, manufacturers of pumps will give you an average, even with the pump curves indicating better performance.

 

I quite often read absolute rubbish on pump systems on TVF but can no longer be bothered at argue the toss.

 

 

If someone accuses you of bullshit hit them back with some facts that cant be denied. I would not give a second thought to any TV  poster trying to get one up.

 

Anyway that's enough with all this pump nonsense.

[Artisi]

1 hour ago, grollies said:

 

This thread is great. I stopped posting on TVF, cause I am busy but also after being accused of bullshitting.

 

I pumped water for 25 years extracting from rivers to flood millions of gallons of water into cross-country pipelines for pre-commissioning projects all over the world. FJ is correct, manufacturers of pumps will give you an average, even with the pump curves indicating better performance.

 

I quite often read absolute rubbish on pump systems on TVF but can no longer be bothered at argue the toss.

 

 

Same here, nearly 50 years in and around the pump industry, hire and sales, service manager, design and manufacture, sales and marketing, product development, trouble shooting, application design etc. Guess I'm getting too long in the tooth to buy into some of the problems raised here as usually it's basic pump class 101. 

Your correct about the rubbish being passed off by "experts" - more often causing more confusion and introducing greater problems than the OP,  and would require more effort to sort out the nonsense than what is required to solve the problem.

Maybe I should hang up a consultants billboard and see what comes in. 

Worth mentioning that pumps are a pretty stupid piece of equipment, put them into a wrong application it will just go ahead and try the best irrespective of what you think the outcome should be. 

Edit to add:

 It's nearly always "the pumps fault"  WRONG, 95% of the time it's wrong application / installation / wrong pump selection. 

Edited April 21, 2018 by Artisi

[Artisi]

1 hour ago, xtrnuno41 said:

I do see they mention also such pumps with a venturi, but to use it for water pumping? you pump water through a venturi to create under pressure to suck in the water then. Would be nice for a mixing pump or create vacuum in which the venturi is mostly used for but for water pumping out of a well? To me it would be wasting power to first create a vacuum to suck the water in. As a rotor with blades should first create the waterflow to the venturi to get vacuum and then can have suction. Wouldnt be my kind of pump, as  a water pump.

Jet pumping, more precisely educator or ejector pumping is highly inefficient, probably overall efficiency depending on design, size, depth etc. could range from 20 to 35% at best 

[whaleboneman]

3 hours ago, Artisi said:

Jet pumping, more precisely educator or ejector pumping is highly inefficient, probably overall efficiency depending on design, size, depth etc. could range from 20 to 35% at best 

eductor

[carlyai]

Your foot valve is 7.5M down so why go with all this jet pump drama when a basic house pump will handle this shallow well.
 
 
 

Hi, I had a double jet 2 pipe system with the jet in the aquifer. Was working well, but would now and then lose prime and I suspected all the water drained out of the pipe through the footer valve, but the times I took the bore pipes up to look at the footer valve it was closed and all looked normal. I water tested the pipes all OK, so I decided that the only other thing that could be causing the problem was the jet. Don't know how, something rusted out, don't know. So I decided to eliminate the 2 pipe system and only have one pipe going down the bore, less to go wrong. Also to change the venturi jet to be right at the pump like the other farmers around have.

While stuffing around I took off the other two pump tank water outlets, and notice a large build-up of very fine sand, which was not evident at the tank water outlet I was using. So it would seem the pump was losing prime through an open footer valve, stuck open with the fine sand, but I guess when I pulled the bore pipes up to have a look the fine sand had washed out and I couldn't see any.
Conclusion was that my double jet pump was working well, but was probably too far down in the aquifer so needed to come up a couple of metres.

I also wanted to see how a set up like the farmers worked.

Good story?



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[carlyai]

ALL jet pumps need the jet in the aquifer if you want them to lift more than 8m or so, that's just high-school physics.
 
The local farmers didn't study high school physics.
 
Both you and the farmers would have a more efficient set up with a conventional centrifugal pump with a double check valve at the bottom of the bore (in case one gets some sand in the seat).

Are you saying the double check valve should be in series?
How much extra dynamic head is going to be added with 2 check valves?

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[Crossy]

1 hour ago, carlyai said:

Are you saying the double check valve should be in series?
How much extra dynamic head is going to be added with 2 check valves?

Pretty much, join them together with a M/M threaded thingy, if one valve gets a bit of grit on the seat then (hopefully) the other will be clean.

 

We don't pump from a bore but we do pump from the river to water Madam's garden. I was pulling the suction every month or so coz the pump started losing prime due to snails in the valve. Replacing the plunger type valve with a flap type improved matters (bigger opening area, the snails now end up in the pump filter) but then it was twigs!! We now have two 3" flap type valves at the end of the 1¹/₂" intake, the springs are pretty light so not adding significant head. Nothing has become trapped for nearly 12 months now.

 

I would use the biggest valve(s) that will safely fit down your bore, the bigger the opening area the less dynamic head added.

 

Our valves are the (relatively) cheap ABS (plastic) ones with rubber seals from the farm shop, but they're easily accessed if they do fail.

 

[carlyai]

People quoting basic physics and basic pumping have got it all wrong...'we do things differently here in Isaan' Isaac et all.
Also basic physics is wrong as things travel faster than light so there goes E=MC^2.


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[Crossy]

By the way, if that air leak is only minor, application of some electrical tape should seal it well enough to see if it is actually making much difference.

 

EDIT I'm no expert, there are many more knowledgeable contributing to this thread, I dropped fluid and thermodynamics after year one to concentrate on things electrical.

[Artisi]

6 hours ago, whaleboneman said:

eductor

Woop's, late at night and bloody spell checker ?

[carlyai]

A few years ago when I looked at the farmer's pump (BIL) I decided that it couldn't possibly work. Artisi convinced me that they do, and later on that the BIL's pump would work.
In my mind I kept seeing this tiny venturi, smaller than the G-spot causing all the action.
What in effect has happened is the low pressure caused by the venturi action has been moved from the bottom of the suction pipe to the top of the suction pipe. So it's critical to have no pipe leaks and a pressurised suction pipe. With the suction pipe full, a centrifugal pump combined with a venturi should make the pump better than just a centrifugal pump alone, shouldn't it?
The pressure side is just pumping the water past the venturi up the suction pipe, not down the pipe.

Derogatory comments and mathematical calculations accepted.





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[carlyai]

Woop's, late at night and bloody spell checker [emoji17]

You're lucky, only picked up on a spelling mistake...you should live in my shoes.

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[Crossy]

44 minutes ago, carlyai said:

With the suction pipe full, a centrifugal pump combined with a venturi should make the pump better than just a centrifugal pump alone, shouldn't it?

Marginally.

 

But it doesn't matter how much "suck" you have you are limited by atmospheric pressure pushing the water up the pipe. 10m absolute maximum, on a sunny day, downhill with the wind behind it and that leaves nothing to actually create a flow.

 

Putting the venturi at the bottom of the bore allows it to give a bit of "push" to the water column (no limits to pushing) and adding a bit extra to the suction head.

 

Obviously, you don't get something for nothing and the extra push comes at the expense of re-circulating some of your output volume.

 

Of course, for really deep wells a submersible at the bottom is the only way to go.

[Crossy]

13 hours ago, xtrnuno41 said:

I do see they mention also such pumps with a venturi, but to use it for water pumping? you pump water through a venturi to create under pressure to suck in the water then. Would be nice for a mixing pump or create vacuum in which the venturi is mostly used for but for water pumping out of a well? To me it would be wasting power to first create a vacuum to suck the water in. As a rotor with blades should first create the waterflow to the venturi to get vacuum and then can have suction. Wouldnt be my kind of pump, as  a water pump.

 

The whole point of using the venturi / eductor / ejector is to exceed the maximum depth from which you can lift water by simple suction (<10m). The venturi harnesses some of the output volume of the pump to give extra "push" at the bottom of the water column. Suctions of 45m and more are readily achieved. http://www.lucky-pro.com/products/Self-Priming_Jet_Pump/MQ255A-DP.asp

 

 

 

[Naam]

14 hours ago, Crossy said:

14 hours ago, xtrnuno41 said:

Er, only a submersible pump is a jet pump in the whole, it works completely submersed in water, so very short suction pipe. 

Sorry, I don't understand. A submersible isn't a jet pump and can lift far deeper bores than either a conventional or jet pump.

 

Our OP has a jet pump with the jet / venturi above ground, no advantage over a conventional well pump (actually less efficient).

i beg to differ Crossy. many rainy seasons ago i took a submersible pump to Nigeria. as i was flying on a 747 this pump become undoubtedly a jet pump.

 

Carlyai mentioned that the venturi is smaller than a G-spot. perhaps this fact overcame the laws of physics?

 

[carlyai]

i beg to differ Crossy. many rainy seasons ago i took a submersible pump to Nigeria. as i was flying on a 747 this pump become undoubtedly a jet pump.
 
Carlyai mentioned that the venturi is smaller than a G-spot. perhaps this fact overcame the laws of physics?
 

It's hard to find a G spot, or anyone wearing one these days. In fact it's very difficult to find a a wifey anywhere near a bedroom these days. Progress? Part of moving forward 4.0?

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[carlyai]

Executive decision ...it's that time again. On closer inspection seems there are 2 leaks. One where the thread has been cracked into that black thinggy and one in the joint on the other side of the black thinggy. A real pain to change.

So better to go back with the twin pipes and double jets as I had before, but pipes not as deep into the aquifer. If this gives problems, then two footer valves.

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[farmerjo]

Hi Carlyai,

While you have it all out do you have access to another pump(surface) to see how much you can draw from the borehole without it running dry to give you an idea of what flow rate your chasing.

  

[carlyai]

Hi Carlyai,
While you have it all out do you have access to another pump(surface) to see how much you can draw from the borehole without it running dry to give you an idea of what flow rate your chasing.
  

Hi farmerjo, yes I do.

Just set up the 300W Hitachi with a 25 mm pipe down 7m and pump for an hour?




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[Crossy]

6 minutes ago, carlyai said:

Hi farmerjo, yes I do.
Just set up the 300W Hitachi with a 25 mm pipe down 7m and pump for an hour?

Sounds like a plan, it may even work so well you'll leave it installed