Water Pump Distance Question

[Beardog]

Hi again,

We just tore down the old shack & built a nice casa & are moving the water tank over to the new house & house pump.

I would like to move the Mitsubishi 300 watt over as well. The pump in question lifts 10n meters from our well & irrigates 2 rai or so at present with no problem. If I move the water pump further from the well it will have to at low season pull up 10 meter down from the well & then be drawn another 70 meters to the pump. It works fine near the source. Can anyone see this may be a problem with the distances? I have everything set in the pump room already for both pumps, but it would be helpful to know if I am pissing in the wind doing this . The pump was overhauled 8 months ago & is very strong.

Thanks a lot

Barry

[farang62]

The only problem I see is if you get even a small leak in the piping to the well, the air will break the suction to the pump. Our rule of thump is keep the pump as close to the pump as possible.That's a lot of pipe to try and find an air leak in. Also pumps especially water pumps loose a lot of efficiency as the suction line and depth increases. More efficient to push the water.

[WatersEdge]

Hi Beardog,

What's the elevation difference between the two locations?

What worked before will work again

if the suction head remains the same,

assuming some practical caveats as pointed out by farang62

Perhaps more than you want to know,

but bear with me in the details:

You have a maximum theoretic suction head of 10.35 meters,

as that's Atmospheric pressure.

That's the perfect theoretic world,

which never occurs in the real pump world.

Your Pump is not 100% Efficient,

so reduce the possible suction head by that multiplier.

Let's give your pump the benefit of the doubt, 80% Efficient.

Now we are down to 10.35 x 0.80 => 8.28 meters max.

That's still not real world,

because there's Friction in the foot valve, and in the suction line.

So perhaps you will get an NPSH (Net Positive Suction Head) of 6 meters

Friction is the silent bugaboo of any irrigation system.

It doesn't stand by the pump and introduce itself to you

as your insidious enemy,

it just quietly steals energy,

putting it into slightly warmer water.

You have not mentioned your flow rate (Liters / minute), nor your current pipe size,

but it's safe to say for a 70 meter run

you should increase the pipe size.

The pipe can't be too big.

I state the obvious because

there are a myriad of bad water pumping ideas floating about Thailand.

If there is an upside down and backward concept imaginable,

it's here and very popular.

farang62 is correct to say you should keep the suction line short as possible.

You can find most air leaks by putting water pressure on the suction line,

and looking for the water leaks,

but air leaks much easier than water.

And who wants to spend their day digging and feeling under pipe in a ditch?

The ultimate method of suction lines is to use the heavy LDPE coil pipe.

It sells in long rolls, up to 100 meters seamless...it's just a devil to join at each end.

It is slightly more expensive than PVC

Thin wall Suction line will collapse under a sudden surge of vacuum.

For instance, if you are running sprinklers at low volume high pressure,

and you suddenly open a discharge valve

The pump tries to rapidly comply

by sucking much more volume through the suction line.

If there is any debris constriction in the foot valve screen

there's a destructive problem.

That's the real world...by unfortunate experience

I have collapsed a 4" PVC 5 bar Pipe down to a shriveled pretzel.

For 70 meters if the suction head is high,

I recommend to avoid trouble by using 8.5 bar pipe.

Back to a small troublesome air leak

Even if the pump still moves water with air bubbles,

the pumping efficiency is reduced and

impeller wear is increased by entrained air.

Air bubbles are as abrasive as sand,

counterintuitive as it is, nice soft air, right?

Hey, Look at the bright side, your water arrives already aerated.

A very small air leak will significantly reduce your possible suction lift.

This whole issue of suction line is practical to me,

because I have a diesel pump out of the river

and the river most years floods a maximum of 6 meters above low season level

Historically I have 3 to 4 minor flood events and 1 or 2 monsters.

So I position my pumping station as high as possible,

now sitting at around 5 meters above low season level

so as to require removing the engine only for the biggy third week of September.

As the pump impeller suffers wear from fine river grit,

eventually it will be unable to pull.

I've already replaced a 3" centrifugal for this reason.

You have a well, probably don't have the constant grit problem.

The ideal situation here is a submersible pump in the well,

should the present centrifugal pump ever fail.

That removes all of this troublesome exercise,

There is no suction pipe worry with a submersible.

A pump seller may recommend a jet pump.

Don't listen to him,

because a jet pump operates on friction,

water turbulence on water

The finest jet pump is only 50% efficient,

and you can't afford to think about that energy bill.

[roundeye]

Hi guys, I am an electrician by trade. Waters edge seems to be very knowedgable in this field. Can someone explain to me why nobody talks about raising a water tank about 2 stories or what ever height is good to supply enough water pressure. It eliminates pipe leaks on the suction side of the pump and the pump only works when the water level drops in the tank. It is still a functioning system here in NYC, USA. as it has been for a very long time. Keep the tank near the supply well and run feed lines out to where you need. I a planing to live in Thailand in about 5 yrs and am planning to do this on my land. Is this not the way to go? What am I missing?

[IsaanAussie]

Hi guys, I am an electrician by trade. Waters edge seems to be very knowedgable in this field. Can someone explain to me why nobody talks about raising a water tank about 2 stories or what ever height is good to supply enough water pressure. It eliminates pipe leaks on the suction side of the pump and the pump only works when the water level drops in the tank. It is still a functioning system here in NYC, USA. as it has been for a very long time. Keep the tank near the supply well and run feed lines out to where you need. I a planing to live in Thailand in about 5 yrs and am planning to do this on my land. Is this not the way to go? What am I missing?

IMHO, this is a different issue. I have 4000 litres of water storage above my pig sty to supply drinking water for the pigs. As you say this is an effective system. But the usage the OP is talking about is volume not pressure. Flooding 15 Rai will require much more water. From memory the numbers are 400 litres per minute for 5 or 6 hours or over 100,000 litres. A very big tank indeed.

[WatersEdge]

From Beardogs original description,

"pull up 10 meter down from the well & then be drawn another 70 meters to the pump."

He wants to locate his irrigation pump near the new house.

It also supplies the domestic water to a storage tank,

and there is a household pump,

which typically have a small pressure tank in the unit.

The only unusual feature is the very long suction line.

A suction line should be as short as the application permits.

If you really need to break that rule,

then all the considerations have to be met.

[Beardog]

From Beardogs original description,

"pull up 10 meter down from the well & then be drawn another 70 meters to the pump."

He wants to locate his irrigation pump near the new house.

It also supplies the domestic water to a storage tank,

and there is a household pump,

which typically have a small pressure tank in the unit.

The only unusual feature is the very long suction line.

A suction line should be as short as the application permits.

If you really need to break that rule,

then all the considerations have to be met.

Hi dam_n good info!

I think it delivers about 50 liters per min.I can only use 300-500 jets for my irrigation instead of the 800 +

that a bore hole would deliver with a 1& 1/2 hp pump. It usually does not have a lift problem till 10 &1/2 meters & then it is a little dicey & some times needs to be reprimed in the lowest point of dry season. It should be no problem with the distance I think. (Same elevation- maybe slightly down hill) The only extra problem I can see is in extreme low season. I have a super industrial Grundafos That would blow every pipe I have & it is way overkill. I planned on using the pump if I ever pick up 10 more Rai.. I could go with a trial & error method & leave there old pipe in but inactive & blocked off & insert it into the new line. I put in several redundant 1" lines(that is what the inlet & outlet is on the Mitsubishi. The lines are glued well. I am super anal when it comes to making sure the pipes are tight before I bury them.Like everyone I don't care to do unnecessary rework & digging! The well is about 4 meters from the tank. You can see the 2000 liter tank in this picture on the left hand bottom side( a sliver of the tank & the pump room will go about 70 meters from the tank to the back left hand side of house. I guess I will have a double whammy as I will have to supply the same 70 meters back to the upper garden so it has water as well.

Thanks for the help! Ah I see the security gates are here got to go.

Barry

[soidog2]

Hi guys, I am an electrician by trade. Waters edge seems to be very knowedgable in this field. Can someone explain to me why nobody talks about raising a water tank about 2 stories or what ever height is good to supply enough water pressure. It eliminates pipe leaks on the suction side of the pump and the pump only works when the water level drops in the tank. It is still a functioning system here in NYC, USA. as it has been for a very long time. Keep the tank near the supply well and run feed lines out to where you need. I a planing to live in Thailand in about 5 yrs and am planning to do this on my land. Is this not the way to go? What am I missing?

We are , were living in Manhattan, that's exactly what I did. I built myself a NYC water tower.

Three stories tall, it works beautifully, the well is about 30m from the house, the tower is about 25m tall.

When the electricity goes off ( all the time, in the rainy season ) we are the only ones with water pressure !

Regards

[IsaanAussie]

I need advice on float switches or valves available here for installation in my raised water tanks. I have a piston pump located about 20 metres from the tanks. There are four 1000 litre Eco plastic tanks in a group. I intend to plumb them together so I can fill all tanks from one which is fed by the pump.

Back to pump control, the real issue. My thought is to use two electric float valves to govern on/off power to the pump rather than using a mechanical float. I have fitted a pressure control switch to the pump but would rather not have the plumbing from the pump to the tanks pressurised all the time.

All thoughts welcome.

Isaanaussie

Edited August 23, 2010 by IsaanAussie

[Beardog]

I need advice on float switches or valves available here for installation in my raised water tanks. I have a piston pump located about 20 metres from the tanks. There are four 1000 litre Eco plastic tanks in a group. I intend to plumb them together so I can fill all tanks from one which is fed by the pump.

Back to pump control, the real issue. My thought is to use two electric float valves to govern on/off power to the pump rather than using a mechanical float. I have fitted a pressure control switch to the pump but would rather not have the plumbing from the pump to the tanks pressurised all the time.

All thoughts welcome.

Isaanaussie

Hi IssanAuassie.

Here is a links from the do it your self forum on floats.I see you have been on the path already! Hope this is what you are looking for.

[WatersEdge]

Hi IsaanAussie,

I have seen three possible options in Thailand

First:

A micro switch mounted above the water,

typically on the outside top of the tank

with a weighted float ball suspended on a string.

The spring on the micro switch arm is strong enough to lift the string,

but not the ball.

When the water level falls so that the ball pulls the string,

the micro switch closes and the pump operates.

This tops the tank off every time the water falls enough to pull the switch closed.

Second:

Switch bubble floats,

two balls on different length electric cords.

I've never torn one apart, so

am guessing they work on a mercury bubble switch

so that if they both are hanging down by the cords in air,

the mercury switches are both closed

and when both are pulling up on the cords floating on high water,

the mercury switches are both open.

Third:

The commercial grade unit that catches my attention is a relay switch,

housed safe and dry in the pump switch box

which simply has two low voltage signal wire terminals.

You choose the arrangement of the wires to exactly suit your application,

which operate in contact with the water.

The function of the relay is reversed

depending on whether you are reading

supply level or

storage level

In your case, you set the tip of the wires at desired elevations.

One wire at the desired low point of the storage tank

and the tip of the other wire at the full level.

When both wires are not touching,

the pump will start,

until both wires are touching,

shutting the pump off.

The function I was interested in it for was

to pump a low producing well almost empty

only when it had refilled completely

Setting the top wire at the static level of the well,

and the bottom wire near the bottom of the well.

When both wires touched, the pump started,

and when both were not touching, the pump stopped.

This relay unit was around B2,000 if memory serves correctly.

Unfortunately for you, it was at the wonderful pump shop in Chiang Mai.

Should I travel to Chiang Mai, I'll be happy to pick one up for you,

but now that I live in Mae Sot, that doesn't happen often.

For other readers in Chiang Mai,

Hang Dong Road southbound lane driving away from Airport Plaza

still within walking distance from Airport Plaza

Immediately adjacent just after TyrePlus with a very visible Chartreusse and Navy sign.

From the street you see only dozens of water tanks

The Owner, maybe 65 years old,

is brilliant on all matters regarding pumps,

and happens to speak perfect English.

[Lickey]

I need advice on float switches or valves available here for installation in my raised water tanks. I have a piston pump located about 20 metres from the tanks. There are four 1000 litre Eco plastic tanks in a group. I intend to plumb them together so I can fill all tanks from one which is fed by the pump.

Back to pump control, the real issue. My thought is to use two electric float valves to govern on/off power to the pump rather than using a mechanical float. I have fitted a pressure control switch to the pump but would rather not have the plumbing from the pump to the tanks pressurised all the time.

All thoughts welcome.

Isaanaussie

Hi IA,

What i did 3 years ago was buy a timer for the borehole pump, it was a bout 2.300bht, then a 2.300thousand litre clay thai round water tank with a 2in outlet for 900bht, then a vane type water pump for 3000bht, [2hp] and an electric float valve [commonly known as a Luk Loy] for 500bht,

The reason for this was to irragate at nights, so the hot sun didnt vapourize the water so quick, so, i would set the timer, the bore pump would start, when the tank is filled, the booster pump would start,and empty it obiviously quicker than the bore pump could fill it,

The system works well, in your case, IA, i would put the delivery pipe into the top of the 1st tank, and join all 4 tanks together at the bottom with 2in pipe so they fill evenly, put an electric float control in the last 1 to cut the motor, if the motor is stopped, with a tank top fill, it only has the waterpressure in the delivery pipe to contend with,

Just an idea, you might want to clean out the sediment in the tanks sometimes, so drain valves in each tank and by pass piping might be the way to go?

Hi Barry, good to see you posting again!

Seems like your pump is already working at its max capabilities, sucking from 10 mts, perhaps you need a bigger depth pump or even a borehole pump down the existing bore, my 1hp franklin will pump from 23 mtrs and then deliver uphill 240mtrs to power 3 big sprinklers, when we extended the banana plantation, the pipeline was 540mtrs, thats when i fitted the booster pump ect [as above] ..

If for eg, you suction pump could lift from 20mtrs, i would raise the pipe 4 or so mtrs above the ground and camoflge it in some way, [paint it green?] this way, your pump should always have the advantage of water wanting to come into it, well good luck with what you decide to do,,,

Cheers, Lickey,

[IsaanAussie]

Hi IA,

What i did 3 years ago was buy a timer for the borehole pump, it was a bout 2.300bht, then a 2.300thousand litre clay thai round water tank with a 2in outlet for 900bht, then a vane type water pump for 3000bht, [2hp] and an electric float valve [commonly known as a Luk Loy] for 500bht,

The reason for this was to irragate at nights, so the hot sun didnt vapourize the water so quick, so, i would set the timer, the bore pump would start, when the tank is filled, the booster pump would start,and empty it obiviously quicker than the bore pump could fill it,

The system works well, in your case, IA, i would put the delivery pipe into the top of the 1st tank, and join all 4 tanks together at the bottom with 2in pipe so they fill evenly, put an electric float control in the last 1 to cut the motor, if the motor is stopped, with a tank top fill, it only has the waterpressure in the delivery pipe to contend with,

Just an idea, you might want to clean out the sediment in the tanks sometimes, so drain valves in each tank and by pass piping might be the way to go?

Cheers, Lickey,

Hi Lickey,

Very close to my concept. I will run one of four main outlet feeds from each tank using 1.5" piping. These will feed the drinkers on four circuits. I will connect the tanks together using the drain outlets with each tank isolated by a valve. That way I can fill only those tanks required at the time or can balance tanks to match usage. A cleanout branch and a feed to a pressurised line for tap water will run off this circuit as well. So the float switch will be in the primary tank not the final one.

[Beardog]

Hi IA,

What i did 3 years ago was buy a timer for the borehole pump, it was a bout 2.300bht, then a 2.300thousand litre clay thai round water tank with a 2in outlet for 900bht, then a vane type water pump for 3000bht, [2hp] and an electric float valve [commonly known as a Luk Loy] for 500bht,

The reason for this was to irragate at nights, so the hot sun didnt vapourize the water so quick, so, i would set the timer, the bore pump would start, when the tank is filled, the booster pump would start,and empty it obiviously quicker than the bore pump could fill it,

The system works well, in your case, IA, i would put the delivery pipe into the top of the 1st tank, and join all 4 tanks together at the bottom with 2in pipe so they fill evenly, put an electric float control in the last 1 to cut the motor, if the motor is stopped, with a tank top fill, it only has the waterpressure in the delivery pipe to contend with,

Just an idea, you might want to clean out the sediment in the tanks sometimes, so drain valves in each tank and by pass piping might be the way to go?

Cheers, Lickey,

Hi Lickey,

Very close to my concept. I will run one of four main outlet feeds from each tank using 1.5" piping. These will feed the drinkers on four circuits. I will connect the tanks together using the drain outlets with each tank isolated by a valve. That way I can fill only those tanks required at the time or can balance tanks to match usage. A cleanout branch and a feed to a pressurised line for tap water will run off this circuit as well. So the float switch will be in the primary tank not the final one.

The answer was same same. The pump works as well pulling the water the distance as well as pushing the distance(providing you don't have the Einstein moment & hook your inlet to the outlet & vice versa.

Note to self..... don't try to work after the sun is long gone!

thanks for the helpful insights.