Ask a Question forum: Does drip tape stretch and shrink in length overnight?

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Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
Frugal Gardener Garden Procrastinator I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest
Photo Contest Winner: 2014 Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database.
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RickCorey
Jun 14, 2017 4:37 PM CST
@Intheswamp installed 200' of drip tape, I'm not sure how many rows or row length.

But I think he sees the tape SHRINK by 6" overnight, even if he stakes down the ends. It pulled the stake out of the ground, it sounds like!

Then he sees the tape weave around and form "peaks" as if it had stretched again, after shrinking, which causes "wrinkles".

Has anyone else seen that, or know the cause, or a cure?

6" sounds like a lot of stretch for a row only 50, 100 or 200 feet long.
Or maybe not - it would only be a stretch of 1%, 1/2% or 1/4%

thread, look around post #18
The thread "8mil versus 15mil drip tape for veg garden?" in Ask a Question forum

post with photo:
https://garden.org/thread/view...
Name: Jean
Prairieville, LA (Zone 9a)
Charter ATP Member Plant Identifier The WITWIT Badge Garden Sages Celebrating Gardening: 2015
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Moonhowl
Jun 15, 2017 8:33 AM CST
Hi Rick.

Could it be the soil expanding and contracting, rather than the tape?

http://www.irrigationtutorials...

I do know that drip tubing exposed to garden sun/heat will contract when ground temperature water runs through the hot tubing...as much a 1 foot per 100 feet of tubing.

http://www.clemson.edu/extensi...

Just a couple thoughts on your question....
Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
Frugal Gardener Garden Procrastinator I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest
Photo Contest Winner: 2014 Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database.
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RickCorey
Jun 15, 2017 7:24 PM CST

Moonhowl said:Hi Rick.
Could it be the soil expanding and contracting, rather than the tape?

http://www.irrigationtutorials...
...


Very interesting article, but I would have thought that soil "in the ground" could only expand "up and down", not sideways. Maybe a raised bed COULD expand sideways by pushing its walls outward.


Moonhowl said: ...
I do know that drip tubing exposed to garden sun/heat will contract when ground temperature water runs through the hot tubing...as much a 1 foot per 100 feet of tubing.

http://www.clemson.edu/extensi...
... .


Wow, that sounds like the problem! What do they DO about that?

I see the Clemsen article refers to "drip tubing" but not "drip tape". It would not surprise me to see the same stretch-shrink in both.

But how to solve the problem?

Is it enough to lay it out and staple ONE end down, then let the other end move when it shrinks and live with that? Maybe running the cold water will remove the objectionable problem, that the tape bends and drips sideways when hot (and empty?)

I'm just wondering, since I only have very short runs and use dripline that looks like 1/4" tubing with with nodules every 6-12", not drip tape. I don't care if it drips up, down or sideways, it all gets into the soil. I've even thought of slipping a 4" length of cotton fabric under some of the emitters, to spread the water around before it sinks into the soil.






Name: Jean
Prairieville, LA (Zone 9a)
Charter ATP Member Plant Identifier The WITWIT Badge Garden Sages Celebrating Gardening: 2015
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Moonhowl
Jun 15, 2017 8:19 PM CST
When soil dries out and cracks form, the soil usually shrinks and sinks. In a container, it draws away from the sides as it shrinks and forms gaps. It seems that extremely dry ground (soil) would do the same to some degree. Using some peat pellets with spaces similar to dry, cracked soil between them within a marked space (12 pellets in a chalk square) did expand both up and out. That may just be the nature of the peat though.


Their answer for installing the tubing that shrank in the heat/cold temperature change:

"Drip tubing is made for use with drip emitters and microsprayers see (HGIC 1812, Landscape Irrigation Equipment Part 3: Microspsprayers & Microsprinklers.) It is quite flexible and will expand and contract with heat. If the tubing is placed in a bed on a hot summer day, the installer should run cold water through it before inserting emitters. A hot piece of drip tubing 100 feet long may shrink up to one foot when cold water is added to it, pulling the last emitter one foot away from where the installer intended it to be. The cold water (normal temperature irrigation water in this case) will cause the sun-heated, expanded tubing to shrink or draw up to the length it will maintain during irrigation. Emitters can then be placed in the tubing with confidence (after first turning the water off!)."

If that is what is happening to the drip tape, I would think either allowing extra length at installation, or mulching over the tape to keep it from heating up, which would also conserve water and help maintain available moisture in the ground.
N'cest pas?













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Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
Frugal Gardener Garden Procrastinator I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest
Photo Contest Winner: 2014 Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database.
Image
RickCorey
Jun 15, 2017 8:30 PM CST
OK, I didn't think that was a "solution" because the tape (or tubing) would still buckle when it expanded in heat.

"Under mulch" does sound like a possible solution.

Or maybe this would count:
"Just don't worry" if it buckles, because the water still comes out and still reaches the soil, whether it shrinks back 100% straight or not." But that feels like cheating!

I was kind of hoping someone would say "yeah, they stretch and shrink for the first few days, but if you keep pulling them straight, they eventually give up and lie flat". But I guess not.
Name: Jean
Prairieville, LA (Zone 9a)
Charter ATP Member Plant Identifier The WITWIT Badge Garden Sages Celebrating Gardening: 2015
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Moonhowl
Jun 15, 2017 9:13 PM CST
I really don't know if the drip tape loses its' elasticity/stretch over time or not. I think to ensure water coverage, I would see how much shrinkage is involved, cut my tape to allow for that and then just peg it at the shortest (shrunk down to) length to keep it from moving side to side or being displaced by tools or critters.

I think "just don't worry if it buckles...." would be my take on it as long as water was getting where I wanted it to go. Thumbs up
Name: Cheryl
Texas (Zone 9a)
Region: Texas Greenhouse Plant Identifier Plant Lover: Loves 'em all! Plumerias Ponds
Foliage Fan Enjoys or suffers hot summers Tropicals Garden Ideas: Master Level Garden Sages Million Pollinator Garden Challenge
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ShadyGreenThumb
Jun 16, 2017 11:09 AM CST
I had to Google "drip tape". Interesting.
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Name: Jean
Prairieville, LA (Zone 9a)
Charter ATP Member Plant Identifier The WITWIT Badge Garden Sages Celebrating Gardening: 2015
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Moonhowl
Jun 16, 2017 11:22 AM CST
Cheryl may have given you a place to find the answer for @intheswamp Rick. A google search brings up all sorts of vendors and info that did not show up when looking for more specific info. D'Oh! Whistling

https://www.google.com/search?...
Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
Frugal Gardener Garden Procrastinator I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest
Photo Contest Winner: 2014 Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database.
Image
RickCorey
Jun 16, 2017 11:38 AM CST
Thanks, guys.

By the way: I see that drip tape lies flat when not under pressure. When you run pressurized water through it, does it "inflate" into a round, thin-walled tube?
Name: Jean
Prairieville, LA (Zone 9a)
Charter ATP Member Plant Identifier The WITWIT Badge Garden Sages Celebrating Gardening: 2015
Image
Moonhowl
Jun 16, 2017 1:19 PM CST
Yup. It lies flat until under pressure. Here is a bit better explanation....

https://www.farmtek.com/farm/s...
Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
Frugal Gardener Garden Procrastinator I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest
Photo Contest Winner: 2014 Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database.
Image
RickCorey
Jun 16, 2017 4:19 PM CST
Thanks! That spelled it out.

And confirmed something I thought:

".. flattened until it is pressurized with water and becomes round, usually at an operating pressure of 10 PSI or below."

Drip tape usually is used at low pressure.
Name: Jean
Prairieville, LA (Zone 9a)
Charter ATP Member Plant Identifier The WITWIT Badge Garden Sages Celebrating Gardening: 2015
Image
Moonhowl
Jun 16, 2017 6:09 PM CST
You are most welcome. Perhaps some of the links above may be of use to @intheswamp

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