Water pump pipe size

[zlodnick]

I'm going to use a 1 inch shallow well pump to pump out of a borehole.

 

I will put 10 meters of pipe with a footvalve down the hole, then at the outlet, reduce it to 3/4 inch.

 

As I understand it, it will be less strain on the pump if the suction pipe (in the borehole), is larger than 1 inch.

 

My question is, how much larger, 1 1/4,......1 1/2......2 inch?

[Artisi]

First up, you are talking about a surface mounted pump, second what is the distance from the pump inlet to the water level in the well, and what size pump / model are you using? 

[zlodnick]

Yes, surface mounted.

 

15 feet from inlet to water level in well.  1 HP Italian pump.

[Lungstib]

In my limited experience its best to have a minimum amount of pipe length on the inlet side, never mind how far you are "pushing' the water down the outlet. Its the inlet side that, if it draws air, will stop water from being delivered. get your pump close to the well if you can. My pipe size was just determined by the fittings on the normal pump here.

[bankruatsteve]

1" should be fine.  

[Artisi]

2 hours ago, bankruatsteve said:

1" should be fine.  

agree , 1" should be ok but going to a larger diameter will not cause any problems - and 15' lift is also ok, and I would stick with the 10m of pipe to allow for lowering the water level during pumping and the  for dry session if it has any effect on the water level.

[carlyai]

First up, you are talking about a surface mounted pump, second what is the distance from the pump inlet to the water level in the well, and what size pump / model are you using? 

Small hijack: Artisi, what are the water flow formulars?

If you have 1" pipe from the bore to the pump inlet, the water level is 15 m down, your pump is 1 Hp and your outlet pipe size is 2"?

How do you calculate gpm or water flow?

 

If you calculate water flow of, say, 20gpm what does this look like? In other words, what should the water flow look like coming out of the 2" hole if the pump?

Should the water flow look like an old person who can't get and erection or a young bull?

 

Happy Songkran.

 

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[zlodnick]

carlyai,

 

 I think you read my op wrong. The outlet is 1 inch, reduced to 3/4 inch.

 

I used the 1 inch pipe I had and it works fine, except that it overheats and shuts off after about 15 minutes. I can't think of any way to stop the overheating.

[wgdanson]

20 hours ago, zlodnick said:

I will put 10 meters of pipe with a footvalve down the hole, then at the outlet, reduce it to 3/4 inch.

 

19 hours ago, zlodnick said:

15 feet from inlet to water level in well.  1 HP Italian pump.

Love the way metric and imperial units are used in the same sentences. .....How much is that 2 x 2 timber.....£1 a metre.

[carlyai]

Love the way metric and imperial units are used in the same sentences. .....How much is that 2 x 2 timber.....£1 a metre.

Sorry wgdanson, you've got the wrong thread. We're not talking about 2 x 2 timber or £1 a metre, we're talking about " and m. Who cares what units are used? It's the understanding that is important.
I've just finished my anger meditation, but some things still piss me off.

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[cooked]

I'm not sure if I understand the OP correctly. You will not be able to 'suck' water from a depth of more than about 8 or 9 metres, no matter how powerful the pump is. Even if you do manage to pump up water, the rate of flow will be minimal. This is why most boreholes have a submersed pump,

The diameter of the pipe only plays a secondary role in as far as water supply is concerned although obviously 1 mm won't give you much joy, and 10cm diameter would be a waste of money. 3/4" or 1" pipe is what most people will go for, the loss of pressure due to internal friction between the water and the pipe walls over a length of 10 metres is not significant.

"Because a perfect vacuum is never achieved and because some lift is lost to friction in the suction line, the maximum actual suction lift for a positive-displacement pump is approximately 22 ft. The maximum actual suction lift for a centrifugal pump is approximately 15 ft when pumping water from an open air tank."

If I misunderstood the OP or I misunderstood my classes in fluid mechanics, just ignore me.

[cooked]

46 minutes ago, wgdanson said:

 

Love the way metric and imperial units are used in the same sentences. .....How much is that 2 x 2 timber.....£1 a metre.

Even in Europe where the metric system has been in place for some time, water pipes are sold in imperial sizes, although the sizes are now quoted in millimetres. 

It doesn't matter.

[zlodnick]

cooked,

 

I understand I will only be able to suck to 8-9 meters. Thats all I want. My submersible burned out, and I just had this shallow well pump that I will use till I get a new submersible or the water level gets too low.

 

 

[Wirejerker]

Your motor is overheating because it’s drawing too much current. Two causes of drawing too much current are 1. Low voltage. 2 Pumping too much water.. Try restricting the flow by closing your delivery valve this will reduce the rate at which the pump has too work.


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[wgdanson]

2 hours ago, carlyai said:

We're not talking about 2 x 2 timber or £1 a metre

I was ! Can you imagine road distances in km, and speed limits shown in mph? Or are they already? Sorry I know it is off-topic.

Edited April 13, 2018 by wgdanson

[Artisi]

6 hours ago, cooked said:

I'm not sure if I understand the OP correctly. You will not be able to 'suck' water from a depth of more than about 8 or 9 metres, no matter how powerful the pump is. Even if you do manage to pump up water, the rate of flow will be minimal. This is why most boreholes have a submersed pump,

The diameter of the pipe only plays a secondary role in as far as water supply is concerned although obviously 1 mm won't give you much joy, and 10cm diameter would be a waste of money. 3/4" or 1" pipe is what most people will go for, the loss of pressure due to internal friction between the water and the pipe walls over a length of 10 metres is not significant.

"Because a perfect vacuum is never achieved and because some lift is lost to friction in the suction line, the maximum actual suction lift for a positive-displacement pump is approximately 22 ft. The maximum actual suction lift for a centrifugal pump is approximately 15 ft when pumping water from an open air tank."

If I misunderstood the OP or I misunderstood my classes in fluid mechanics, just ignore me.

I wouldn't like to be impolite by ignoring you, but 15ft is too low a number for correctly sized pipework but without a pump curve showing NPSH, knowing the elevation of the installation, water temperature, flowrate etc of the installation I think you can for most purposes you consider 23 / 25 as a reasonable suction lift. As the OP is sighting 15ft lift, we can assume this is within the pumps capability. 

The overheating is another unrelated problem, and as already indicated by wirejerker probably low voltage and maybe the cause of the submersible burnout. 

[cooked]

1 hour ago, Artisi said:

I wouldn't like to be impolite by ignoring you, but 15ft is too low a number for correctly sized pipework but without a pump curve showing NPSH, knowing the elevation of the installation, water temperature, flowrate etc of the installation I think you can for most purposes you consider 23 / 25 as a reasonable suction lift. As the OP is sighting 15ft lift, we can assume this is within the pumps capability. 

The overheating is another unrelated problem, and as already indicated by wirejerker probably low voltage and maybe the cause of the submersible burnout. 

OK but he is talking about 10 metres. That or he is being imprecise which is why I tried to stay polite.

You are mentioning factors that you can indeed use when passing a University exam but which have little practical application in a muddy hole.Water temperature? Come on.

[Artisi]

26 minutes ago, cooked said:

OK but he is talking about 10 metres. That or he is being imprecise which is why I tried to stay polite.

You are mentioning factors that you can indeed use when passing a University exam but which have little practical application in a muddy hole.Water temperature? Come on.

He was talking about 10 m of pipe with   a water level of 15m. 

[zlodnick]

Artisi,

 

The footvalve is down 10 meters and the water level is down 15 feet ( just over 4 meters).

 

I checked the voltage,   230 v. 

 

I haven't tried turning the tap down to reduce the water flow, as was suggested. I just don't know, but it would seem to me that would make the pump work harder?

[bankruatsteve]

4 minutes ago, zlodnick said:

Artisi,

 

The footvalve is down 10 meters and the water level is down 15 feet ( just over 4 meters).

 

I checked the voltage,   230 v. 

 

I haven't tried turning the tap down to reduce the water flow, as was suggested. I just don't know, but it would seem to me that would make the pump work harder?

Think pressure.  Once the pump gets the pressure to pull the water out, it is easier to maintain if output is lessened.

[zlodnick]

Thanks, I'll give it a try.

[Wirejerker]

Is that 230v at the pump when it’s running or is it 230v with the pump not running?


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[Artisi]

2 hours ago, zlodnick said:

Artisi,

 

The footvalve is down 10 meters and the water level is down 15 feet ( just over 4 meters).

 

I checked the voltage,   230 v. 

 

I haven't tried turning the tap down to reduce the water flow, as was suggested. I just don't know, but it would seem to me that would make the pump work harder?

Reducing flow by increasing head on a radial flow centrifugal pump reduces power as well as reducing losses on the inlet side of the pump, however you can only increase the head on the pump until the head following the reducing valve doesn't meet your needs, ie., the flow/pressure at the taps or into your holding tank. 

[Artisi]

On 13/04/2018 at 8:54 AM, carlyai said:

Small hijack: Artisi, what are the water flow formulars?

If you have 1" pipe from the bore to the pump inlet, the water level is 15 m down, your pump is 1 Hp and your outlet pipe size is 2"?

How do you calculate gpm or water flow?

 

If you calculate water flow of, say, 20gpm what does this look like? In other words, what should the water flow look like coming out of the 2" hole if the pump?

Should the water flow look like an old person who can't get and erection or a young bull?

 

Happy Songkran.

 

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Sorry for late reply, but it is songkran and there is so much water about it just confuses the issue?

However, to fully answer your question, to decide on the flowrate from the pump you need a performance curve for the pump or a tabulated table showing flowrate against suction lift / discharge pressure, now if you want to become very pedantic you need to calculate the total losses on the inlet side and the losses on the outlet side.

As for 20 gpm from a 2" discharge, I would expect it to exceed what us old guys are capable of  - - but having never flow tested a young bull I can't give you a definite answer on that particular point. 

[zlodnick]

230v not running

[carlyai]

Sorry for late reply, but it is songkran and there is so much water about it just confuses the issue[emoji28]
However, to fully answer your question, to decide on the flowrate from the pump you need a performance curve for the pump or a tabulated table showing flowrate against suction lift / discharge pressure, now if you want to become very pedantic you need to calculate the total losses on the inlet side and the losses on the outlet side.
As for 20 gpm from a 2" discharge, I would expect it to exceed what us old guys are capable of  - - but having never flow tested a young bull I can't give you a definite answer on that particular point. 

Thanks for the reply. Sorry for this...I seem to think of something on the spur of the moment and hijack people's threads. I'll do some calcs and start another thread.
Great Sonkran...everyone happy.

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[Naam]

On 4/13/2018 at 3:54 AM, carlyai said:

If you have 1" pipe from the bore to the pump inlet, the water level is 15 m down, your pump is 1 Hp and your outlet pipe size is 2"?

How do you calculate gpm or water flow?

with the water level 15m down there's nothing to calculate if the surface mounted pump is not a jet pump.

[bankruatsteve]

3 minutes ago, Naam said:

with the water level 15m down there's nothing to calculate if the surface mounted pump is not a jet pump.

I believe the OP says 10m of pipe with water level starting at 15ft.

[Artisi]

1 hour ago, Naam said:

with the water level 15m down there's nothing to calculate if the surface mounted pump is not a jet pump.

really depends on how pedantic you want to be, but you're  correct , a 1" pipe x 10m on the inlet side of the pump wouldn't /shouldn't  cause any problem.

[Wirejerker]

You need to measure the voltage at the motor when it’s running. A low voltage would of caused a premature failure of the submersible and this needs to be checked before you put in a new pump


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