Pipe Size Matters - How to Read Irrigation Friction Loss Charts
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- Äas pĆidĂĄn 15. 07. 2024
- In this video, Andy shows you how to read an Irrigation friction loss chart.
Irrigation friction loss charts are used to estimate the amount of pressure loss that occurs when water flows through irrigation pipes and fittings. These charts provide a graphical representation of the relationship between the flow rate, pipe diameter, and pressure loss.
Hunter Friction Loss Tables
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Irrigations Fittings
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00:00 Introduction
00:31 Polyethylene and PVC Pipe Diameters
01:26 Pressure Loss and Friction Loss
02:58 How to Read Friction Loss Charts
10:19 Outro
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Determine the flow rate: The first step is to determine the flow rate (in gallons per minute or GPM) of the water that will be flowing through the irrigation system. This can be done by measuring the water flow using a flow meter or by estimating the flow rate based on the size of the irrigation system and the type of plants being irrigated.
Identify the pipe diameter: Next, you'll need to identify the diameter of the pipe that will be used in the irrigation system. The pipe diameter is typically measured in inches and can be found on the edge of the chart.
Locate the appropriate flow rate and pipe diameter: Once you know the flow rate and pipe diameter, you'll need to locate the corresponding values on the chart. This is typically done by following a line from the flow rate axis to the pipe diameter axis.
Identify the pressure loss: Once you've located the appropriate point on the chart, you can read the pressure loss (in pounds per square inch or PSI) that corresponds to the flow rate and pipe diameter. This is typically found on the pressure loss axis on the edge of the chart.
Account for fittings: Finally, you'll need to account for the pressure loss that occurs due to fittings such as elbows, tees, and valves. This can be done by adding the pressure loss values for each fitting to the total pressure loss calculated from the chart.
It's important to note that irrigation friction loss charts are based on certain assumptions and conditions, and the actual pressure loss in an irrigation system may vary due to factors such as pipe material, temperature, and elevation changes. As a result, it's a good idea to perform actual measurements and calculations to ensure accurate results. - Jak na to + styl
Also, observe pressure during the actual time you will be irrigating. I got screwed when I used mid afternoon pressure for design only to find out after installation that my city pressure drops 25lbs in the early morning when I water. Called the city and was told sorry, you get what you get. No boosting on their side. Iâm working on reducing my GPMs to combat the loss. My entire system is 1â poly. Thank you for the information, being a firefighter for 25 years, Iâm familiar with pressure loss. Just have to apply it.
Yes, thank you for mentioning this! Itâs super important to check pressure at the time you intend to operate the system. I recently installed a cloud-based pressure transducer on a residential home and saw the pressure spike at 12:01am, and then drop by 20psi reaching a low point at 10am - and this pattern repeated daily.
Is a booster pump an option for you?
@@Andy_Humphrey I consulted a local installer and was told to make sure my zones are not over 12 gpm. So I'm going to look at that and try some landscape changes before going down the pump road.
Good luck!
Professionally done video! Thanks!
Thank you! đ€
Just started landscape irrigation course at my college. this video helped me to understand the subject better. Thank you!
@tinatinm so glad it helped! It can be a bit confusing at first, then once you grasp it, everything makes more sense.
What college are you attending?
Great video been looking all over for this info. Thanks for the link as well... Happy sprinkling
@jaysoberanes15 - excellent, glad this was helpful! If you don't mind me asking, what specifically were you searching for, or looking for?
This video is very well done. The principals discussed can also be applied in a verity of applications. Great to see this type of content.
Cheers.
Wow, thank you!
Love your CZcams channel! I just finished watching this video and several others of yours. I'm at the very early stages of designing an irrigation system at my house. I've never done this before and I see from others that have asked you questions here, you are a great sprinkler resource.
The area that I want to sprinkle is for the "sports" area of our backyard. This is where we play badminton and croquet. It gets full sun and is a challenge to keep grass growing, especially when we are using it often. The area is nominally 50' x 25'.
I have a dedicated irrigation line from the city water system. Just today (9 am, Sunday), I measured the static water pressure to be 44 psi. This is the pressure at the hydrant in my yard AFTER the city meter and the back flow preventer. Last week I measured the water flow coming from the hydrant using a 5-gallon bucket and got ~50 GPM.
For the sprinkler system, I plan to tee into the existing PVC line the runs between the back flow preventer and the hydrant. I think this line is 1", but I still need to verify. The elevation of this tie in point is about 3' ABOVE and only about 20' away from where the edge of sports field. Therefore, I will have the benefit of some increased pressure in the system as it flows down to the sports field.
My goal is to have an effective, trouble-free sprinkler system that I can install and maintain myself. I am willing to pay more for any system component if it will ensure I can meet these goals.
My basic questions are:
1. How many zones do I need?
2. What type of head(s) should I use and what configuration is best?
3. What controller do you recommend? (Due to the remote location of the tie in point, there is no access to Wi-Fi and limited access to electrical.)
4. What type and size of pipe should I use?
5. Any other design elements or tips I should know before I proceed?
I'm hoping to get this installed in the next couple of weeks to be ready to plant grass (from seed) in the bare spots for the fall. I thank you in advance for any help you can provide.
Great questions, and thank you for your kind feedback.
This is a situation where I'd recommend a consultation with a professional to ensure that you get this right. I'm certainly happy to help, below is a link to schedule a technical meeting.
Couple quick thoughts based on your observations.
1 - The static pressure reading of 44psi is not effected by the backflow, pipe friction loss etc., unless you tested the dynamic pressure while the system was running. Static water pressure will be the same at all points, with the exception of high/low areas due to gravity. If the static pressure is 44psi, it is likely that the dynamic pressure will be more like 35psi, in which case a booster pump is recommended.
2 - 50gpm sounds suspect. Double check the calculation. If you tested it from a garden hose hydrant, it should be more like 5-8gpm. A fire hydrant/hose would be more like 50gpm, and perhaps that is where you tested from?
Look forward to learning more and providing assistance should that be helpful.
Thanks again for your kind words!
Scheduling link: calendly.com/andyhumphrey/technical-support
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Thanks for the video, and thanks in advance for help on this. Iâm confused. Is water pressure different from pressure within the pipe? You say if you were to put 50 gallons/min into that pipe it would blow a fitting. Wouldnât it be the increase in pressure inside the pipe that would blow a fitting? Yes the water moves faster but I would think it would create more pressure in the lines? (Even though you say you can only increase pressure in certain ways). Iâm a math guy who likes this stuff but am just learning it.
I got some great answers in another of your videos. Thanks
How do I calculate static pressure if my irrigation water splits off from the house right at the town water meter, and my irrigation system even has a knob to adjust the pressure. Every zone is fine but one is overloaded with heads and a drip line and doesnât work well.
Is there a formula how much each head drops the pressure? Are some sprinklers better for low pressure and/or low flow? (Rotors, spray or rotating nozzles, impactâŠ)? Iâm thinking of trying an impact at the last sprinkler of the zone to see if I can get more range with it.
Water pressure can only be increased with a pump, or gravity.
The best example of false pressure if putting your thumb over the end of a garden hoseâŠthis does not increase the pressure, it increases the velocity/speed of the water.
Hi velocity is what will create problems. It is for this reason, that the recommended velocity is under 5 ft./sec
Static water is measured with a pressure gauge. To calculate the dynamic pressure, you will need to know how many gallons per minute you are using, the distance the water is traveling, and what the water runs through in between (size of the pipe).
If you have low pressure, the best sprinkler to use is a pop-up spray head, with the lowest flow nozzle you can find that still covers the distance youâre looking for. Do not use rotating style nozzles, use a standard matched precipitation rate fixed spray nozzle. These will generally operate as low as 20 to 25 psi
Impact sprinklers are not a good choice for low pressure because they typically require a higher flow rate.
Please I need to know how I can make design for irrigation net work for the commercial site
@midofox356 - Iâm not sure your question, but if youâd like to book a call with me, Iâd be happy to consult with you:
calendly.com/andyhumphrey/technical-support
Im wanting to run a water line to another side of my property for a 2 acre garden area, however the distance is 1600ft from the well and 50ft higher in elevation. Id like to have some serious flow and pressure to irrigate, any thoughts. I was thinking 1" high pressure poly pipe with a booster pump on a dedicated line.
For that distance, youâll likely need a 2â pipe, depending on how many gallons per minute you need.
Letâs assume you need 15gpm.
15 gpm through a 1â PE pipe will generate 5psi loss per 100ft.
At 1600ft, that is 80 psi loss (1600/100 x 5).
The elevation change of 50 will reduce the pressure by another 21.65psi (50x0.433).
So youâll have 100psi loss
Using a 2â poly pipe will only be 1.5psi loss per 100ft.
@@Andy_Humphrey Thank you so much for your help đ
@@JohnDoe-id9hi my pleasure. If you need more engineering assistance you can schedule a call with me and we can go through it one-on-one.
calendly.com/andyhumphrey/technical-support
It seems i have 1/2" main in my home, OD is .91. Best charts i can find for galvanized seem to point to 1/2" ID. Can i just increase the size of the pipe where ever i tie in after the meter to say 1" and this will give me a higher flow rate? Static pressure was about 62psi.
Hard to say for sure, however, I would not plan on a higher flow rate. Increasing the pipe size will reduce your friction loss (psi over distance) but the flow is generally limited by the incoming source. Also note that old galvanized pipes are often restricted due to corrosion inside the pipe, so you may have even less flow. Google that one :)
@Andy_Humphrey ah okay. I have 140' to reach my farthest sprinkler with 8gpm. Is 8gpm to low to run the Hunter MP1000 rotators? Or how can I check if I will keep at the 40psi rating before I start purchasing the supplies? Thanks for all the help
Is that 140ft of galvanized? Take a look at the MP Rotor Performance Charts to calculate the actual flow rate. Then based on that, you can determine the friction loss. Iâll a link to the performance charts: www.hunterindustries.com/sites/default/files/CA-Cutsheet-MP-Rotator-US.pdf
When checking the friction loss charts am I supposed to use the 8gpm that my home provides? Or the 5gpm that the largest zone will need?
Use the gpm for the specific zone (best to use the largest zone).
So does it mean the the closer to the 5 velocity fps the better? Not exceeding 5.
that is an interesting thought, but not exactly. There really is no "better" velocity, only not to exceed velocity, which for irrigation is 5fps. Slower velocity will have no effect on pressure. Actually, that's not true, you will have less pressure loss (therefore conserve pressure) if the velocity is lower.
How do I test the water pressure going to my irrigation and water follow? Testing at the spigot wouldnât be accurate as the spigot is connected to my house and likely after a regulator, and my irrigation line branches directly off the main water supply line before it comes to the house.
Take a 5g bucket open pipe full count the number of sec it take to fill the bucket 5G Div Sec X 60 = water flow per min
Static pressure will be the same anywhere you tested on your house. Just make sure there is no water running when you test the pressure.
Itâs a bit confusing to think about it first, however, static water pressure is just that, water thatâs not moving. The only difference to the readings will be due to elevation.
We have free ditch water in our subdivision for irrigation (~30-50' higher than house location). It's delivered to each 5 acre lot via a 2" riser pipe (think horizontal rectangle with the house and riser pipe in the NW corner). I'm allowed a max 5 HP pump. Is there any issue with using qty (4) 2" pipes for the long runs and then branching off them for each sprinkler head or is it better to reduce the size? What happens if you have too large of a pipe? Thanks
A larger pipe than is necessary will not cause harm. It will reduce friction loss, and the resulting dynamic pressure will be higher. Itâs most costly, but if in doubt, size up.
Regarding your other question, if you can run 1 pipe and have adequate dynamic pressure, Iâd recommend that. Extra pipes will be extra maintenance cost.
My recommendation is to design the size of your zones, based on the gpm available, and pressure calculations from the 5hp pump and elevation changes.
If you would like assistance you can book a call with me and we can go through the calculations/design together.
@@Andy_Humphrey thanks! I saw your calendar link from another comment and will take you up on that offer but will probably be after the summer. thanks again! enjoying your channel. Just subscribed.
Thank you!
Hi sir can you help me in my design in irrigation..what is the best pipe size for irrigation with a 12 hectare rice field sir..I hope you would answer this question.. Thank you very much in advance
Hello. I wish it was a simple answer; however, this is complex and requires additional information about your water source, existing pressure, and how you plan to irrigate the rice crop. If you are interested in technical design assistance, please book a consulting call using the link in the description.
is the friction loss in head form?
@kennethrevilla639 these charts, used for irrigation design, typically display pressure in PSI. This is most common for irrigation contractors, etc.
You can convert psi to foot-of-head by multiplying psi x 2.31. Example: 50psi x 2.31 = 115.5 foot-of-head.
In reverse, there is 0.4333psi in 1 foot-of-head. Example: 100 foot-of-head = 43.33 psi
Does this help?
@@Andy_Humphrey I'm learning new ways to find friction loss. I'm reviewing bernoulli's equation where all must be in term of "head" units must be either in meters,ft or inch. so if I multiply 50 psi and 2.31. the friction loss is 115.5 ft? where did 2.31 come from?
oh i got it. pressure is also equal to (density)(gravity)(head) @@Andy_Humphrey thanks :D
@@kennethrevilla639 you got it - that is some good Nerd speak right there!
Very helpful and well done, but that clicking sound effect after every word is very annoying
Agree and thank you