Monday, 24 August 2020
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Dear all,

I need to add cap to an existing system which is open natural canals,

To add the caps I need to estimate the flow rate and the pressure demand of covered areas by the canals..

All I have is the plants which are shrubs areas, with trees or palms..

No equipments existed..

 

what I did, I placed the following schematic irrigation area: 

SHRUB DRIPLINE 0.9 GPH @ 12" O.C. (3.5 L/H @ 0,3M) with 

precip: 36,5760

pressure: 1.72 bars

When using the advised schematic I got 628 l/min

and earlier I did my manual calculations to get the approximate irrigation demand of these areas depending on the wise individual demand of each type of plant.. and it was 22382 l/day

 

am thinking that there is something wrong about these two results rather than I believe that choosing the advised schematic to get an approximate flow rate and pressure is not enough as logically I consider it only covering the shrubs areas excluding the need of the existed trees or palms.

 

so my question is,

what is the best strategy to do in this situation in general?

and what is the best schematic irrigation choice can fit both shrubs and trees in here?

 

Thanks in advance,

Nibal

3 years ago
·
#3782
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Nibal,

I am not sure I follow. You may be thinking of a CAP in the wrong use. It sounds a little like you are trying to use a CAP as the POC? Or are you using the CAP for what the irrigation types/demands need to be.

Reason this is important is because a CAP is a set of demands, not what is available.

If you use a CAP, you technically do NOT need to use Schematic for anything (unless you are using Schematic to calculate what you need to put into your CAP). If you ARE using Schematic, and the numbers are different than what you are calculating manually, it is more than likely that your Area OR Precip is different in the Schematic item vs your Manual calcs.

The thing to remember as well is that the Schematic is based solely on Area and Precip, whereas your manual calc seems to be plant specific. Those are not apple to apple comparisons.

 

Ultimately it sounds like if you know what plant demands you need, just enter that into a CAP and be done, don't bother with Schematic at all.

 

Please let me know if I am close in my assumptions here, or if I am off base.

Jake,

 

My project is 2 parts,

Part 1  needs a full irrigation design,

 

Part2(Surrounded with yellow dashed polyline in the attached file),

the client wants to water the plants existed in this part through EXISTED open canals,

 

So what I did, I planned a full irrigation design for part 1,

 

and I needed to connect the part 2 of the project to my irrigation system of the part 1 through caps,

Here I need to ask is my way of approaching the whole project is logic.

 

To get the caps flow rates and pressure requirements of part 2,

I needed to use the schematic irrigation to get the approximate flow and pressure so I'll be in the safe side when sizing the whole project,

but the schematic choices cover only shrubs areas not covering the existed trees in the same area.

so if the planting area has both shrubs and trees, the advised schematic irrigation won't be enough but I found that this could be sorted out for one area when adjusting the precip rate,

 

When I used three ways of check up the results for an example area I got the following results,

1- Putting regular equipments and attach them to a drip and trees valve and sizing them as usual  

Drip valve 629 l/m

Trees valve  57 l/m

Both 629 + 57 = 686 l/m

2- The schematic irrigation gave me 629 l/m(which is covers only the shrubs) however when I adjusted the precip of the schematic irrigation I could get EXACT number(686 l/m) to the number in point 1.

3- The manual way 

Palms trees 15 nos X 120(l/day) = 1800 l/day

Shrubs areas 1029(sqm) X 20(l/m) = 20582 l/day

Both = 1800 + 20582 = 22382 l/day

 

15.54 l/m which i got from manual calculations  is very far from 686 l/m which I got from point 1 & 2 above.

In regard with that the Schematic irrigation is based on Area and Precip, whereas my manual calculations are following the individual plant water needs as mentioned above, I can totally understand that , but number I should consider it as safe side, as I need to build  the whole system considering these number.. am just a little bit confused.

 

 

Am just wondering now , can the difference between the two numbers be the duration of the watering time during the day,

for example, 

if we divide 22382 l/day  = 32.6 min/day

                    686 l/m

Think this should make sense..

 

 

Nibal

3 years ago
·
#3788
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Nibal,

Thank you for the deeper explanation. Yes, I think this is making more sense now. I will tell you right now, I am not a fan of math, especially at 3am. So bear with me :)

1-Your last schematic statement is key for sure. The numbers generated by Land F/X are the demands of the system in a given minute for that equipment specifically, in your case #1 & #2 is right at the 686 l/m mark. So you do need to focus on the overall amount of water that will be generated by the system (what Land F/X is coming up with) and put this in the CAP so the pipes can size properly to supply that demand. 

2-So, having said that, It does seem that your case #3 is lacking something, or something is not quite right (or quite possibly it is just me). I see your Shrub area set to (20) l/m but totaled as l/day? How is this working? Assuming all of these numbers are correct, the grand total "manual way" is the plants demand, Correct?

OK, so we have (1)- our Total water emissions to our areas (686 l/m) and (2)- our total plant water requirements (22382 l/day). We now need to see how long the system needs to run in one day to supply all this water to the plants (22382/686 = 32.6 min/day)

Breaking it down further as a cross check:

  • Take our 32.6 min runtime and apply it to the Drip valve demands (32.6 x 629 l/m = 20505 l/day (very close to your manual calc of total water needs to the shrub areas)
  • Take our 32.6 min runtime and apply it to the Tree demands (32.6 x 57 l/m = 1858 l/day (also right there with your manual calcs for palms)

 

I hope I made sense, and that the sense is accurate! I might not have any recollection of this in the morning ;) But let us know if you have any further questions.

**I would love to hear from Seaweed or the other Irrigation masters with this, just to make sure I am not steering you in the wrong direction.

Jake,

Many thanks for the prompt reply.

and Sorry for the mistake.. its actually 20 l/day NOT 20 l/m

Think you could point to it greatly..

So now, its logic to place the cap using the approximate schematic calculations through adding both shrubs and trees flow rates

and then I size the system normally..

 

I think I still have an inquiry,

Since the cap somehow is having a flow rate and pressure, same like the valve, why can't we call out it? and it can be shown properly in the valve schedule with number instead of unknown AS ATTACHED..

Nibal

3 years ago
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#3811
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Nibal,

I apologize, I could have sworn I replied to you about your CAP question. If you want the CAP to show up with a given number in the schedule, simply use the ID cap symbol. You should be able to see how to do this in the following video (at about 2:40).

Put A Cap On It

If you have further questions please let us know and we will help you out.

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