Gravity fed drip irrigation

Hi all,

I am looking at gravity fed drip irrigation on my farm. If you are using it I would like to hear your experiences.

A local distributor of a reputed drip manufacturing company is advising me against it because it may clog the drip due to lower pressure. My farm has a small hillock which can provide atleast 30 feet of elevation which can provide around 14 PSI of pressure (according to couple web sites) which I think would be adequate. Of course I will have to consider the friction loss due to long pipes from source to the irrigated plot.

Thanks!

-Satish
Satara, Maharashtra

Hi Satish

IDE offers technical manual for low cost gravity fed drip irrigation. Just search for IDE drip irrigation.

I am curious though, how are you taking water to the top of the hill, or is there a water body?

Thanks

Though i am pretty newbie in this drip irrigation , am curious to know how did you arrive the PSI value?

@ Satish - Theoretically talking @ 30ft bottom of the water source, you should be seeing 89611 pascal i.e 13PSI. But taking into account the pipe friction you should be having lesser pressure at the bottom.My bet would be to ask the drip supplier the min pressure above which it doesnt clog and see if it will suit you.If the water source is a tank why not raise it little more untill you get the desired pressure?

@sanjeevrk - Formula for pressure is P = p * g * h

Where P is Pressure in pascal, p is Density of water i.e 1000 kg / m3, g is Acceleration due to gravity i.e 9.8 m/s2 & h is distance between top and bottom of the water source measured in meters.

In this case its P = 1000 * 9.8 * 9.144 m = 89611 pascal

1 pound per square inch (PSI) = 6894.75729 pascals ` 12.99PSI = 13PSI

Regards,

Saravana Kumar
CEO
Greencurrent Solar Energy Systems

Also, @ Satish, commonly available drip emitters generally would be 4lph or 8lph with rated pressure around 13 and 17 psi respectively. Either cases the pressure @ 30ft i.e 13psi would not be sufficient after frictional loss in drip lateral pipes.

My suggestion is to first identify what is the amount of water needed in lph and choose between 4lph emitter and 8lph emitter and arrive at the psi and suitably increase the height of the tank.

FYI, over height will lead to more pressure and needs pressure regulators post filtration stage and under height will lead to clogs.Striking a balance will be definitely helpful.

Regards,

Saravana Kumar
CEO
Greencurrent Solar Energy Systems

Believe me, the actual pressure will be much more than 13/14 PSI.

How? the equation doesn’t take into account the area of the water surface. If you had a pipe full of water to the height of 30ft, your calculation is right. But that is not the case.

The actual pressure will be - P(act) - somewhat less than the following :
Pressure (in PSI) * Area of the tank surface (in ftsquare).

We too have a tank of 8ft radius at around 30ft. As per your calculation this would result in just 14PSI of pressure, which can no way run a sprinkler (sprinklers typically require 80 ft of pressure head or 35PSI of pressure). But in reality, we are able to easily run 8 sprinkers!

Regards,
Mahesha

Dear Mahesha,

Are we talking about 8ft radial tank of height 30ft from ground level or 8ft radial tank of 'x" height located at 30ft above ground level?

Anyways, very curious to know if the 1st setup is successfully running 8 sprinklers  ::)

Regards,

Saravana Kumar
CEO
Greencurrent Solar Energy Systems

QJ7081,

Not sure if you’re still around but what you require is probably not going to be compatible with traditional drip irrigation systems.

If you download the IDE manual I suggested (can be found here | 12 MB), you will see their system will work with just a 5 feet head and gravity flow.

Key limitation is the area covered, which is 1000 sq.m. So you will require about 4 of these for an acre. On the other hand, key advantage is that you will save a lot in recurring energy cost. 

Dear Saravana kumar,

Our tank is of 10ft height and 8ft diameter (I erroneously mentioned as radius). It holds more than 12000 liters of water.

And we have been already running sprinklers since 6 months. We run 8, and at some points at the beginning of the pipe, even 10 sprinklers work without problem.

Ah…now it makes sense. My calculation works for height 1ft but when tank height increases the volume as well increase there by we get a increase in pressure.

Thank you for sharing the input Mahesha.

Regards,

Saravana Kumar

hi,
a fellow farmer in my village is practically running the in line drip and mini sprinklers with 4ft dia cement tank erected on roof top of 2 storey building (i.e a hieght of 20to 25ft). here he owns  03 acres of land and the tank is located in the middle of the land, may be he is acheiving the required pressure, since the length of the pipes he has to run is very short. it is possible in other places too if similar points are taken into account. thanks&regards  -prathap.

Dear all,

Thank you for all the responses. Sorry for the late response as I was away on a farm visit in Tamilnadu.

The water will be pumped to the tank on hillock from borewell at lower level. But I can do that any time when the electricity is available as against running drip system on pump directly which may not be possible due to erratic electricity supply.

Looks like use of drippers designed for gravity fed irrigation might be the way to go.

I will look at the IDEal and other micro irrigation systems. Thanks again.

Regards,
Satish

Thanks for the info.

can you tell me where to get/purchase the kits/equipments they display in website. I tried using google . but i was unable to find the details… any info will be really helpful
Thanks… Can you suggest from where one can buy the kits/equipments they mention in the website?  I tried searching for it but no success…

Dear 7081,

recently i have installed drip tape in my field with gravity based system. my water tank hight will be max 15 ft. my plot size is around 1/4 acre. it is working perfectly well. also i have direct connection to inline drip pipe with emergency discharge to tank - i never found that water is getting discharged in tank - so i think i can assume drip pipe also works fins in the same pressure. So 30" will work perfectly well

there are two important things you need to remember:

  1. water supply to the submain should be sufficient ( i had used 2.5" hose pipe)
  2. drip lateral length - the shorter the length the better the water distribution. i had used around 70" in either side for my field.

Regards,
Joydev

Dear Joydev,

Thank you for your response. I am going for the gravity fed system.

I have contacted couple of vendors of gravity fed drip system (Driptech is one).

Regards,
Satish