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View Full Version : What is the max flow (gpm) in 1" poly pipe?


soafone
08-10-2012, 09:04 PM
I know the 5 ft/sec. rule says you should not exceed 12 gpm when designing your zones using one inch poly pipe, but how many gpm's will a one inch poly line actually allow (max)?

How about 3/4", and 1-1/4"... what are their max?

I read somewhere that many designers ignore the 5'/sec. rule and design based on 10 ft/sec.

Wet_Boots
08-10-2012, 09:07 PM
I have an old system blowing 50 gpm through a short (inaccessible) length of one-inch poly

Mike Leary
08-10-2012, 09:42 PM
I read somewhere that many designers ignore the 5'/sec. rule and design based on 10 ft/sec.

Read on, the five scond rule was not invented because no one had anything better to do. I've heard of someone raising the 5' rule, but I don't agree.

hoskm01
08-10-2012, 10:01 PM
I read somewhere that many designers ignore the 5'/sec. rule and design based on 10 ft/sec.


Some say 7.5 fps. What's your comfort level at?

Like Mike said, no one just pulled 5' from their arse and called it macaroni.

txirrigation
08-11-2012, 07:26 AM
Stay with 5fps when using plastic.

7.5 is what people say about metal, but we use 9fps as well as most irrigators.

CAPT Stream Rotar
08-12-2012, 03:38 PM
I've put 20 gPm through 3/4 for a short run
Then to a drip 4 way

No clamps and 6 years later it still holds
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Wet_Boots
08-12-2012, 03:53 PM
do they even have friction loss tables for flows way beyond design guidelines

1idejim
08-12-2012, 05:30 PM
That question has "WHY" written all over it Morris.
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Wet_Boots
08-12-2012, 08:10 PM
It's not so much as wanting a design guide for wandering astray as it is wondering what's going on in existing systems that are using flows that are off the charts.

1idejim
08-12-2012, 10:56 PM
It's not so much as wanting a design guide for wandering astray as it is wondering what's going on in existing systems that are using flows that are off the charts.

they make lots of noise and things break or wear out quicker
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Wet_Boots
08-12-2012, 11:00 PM
Some of them are taking a few decades getting to the point of breaking down.

1idejim
08-12-2012, 11:32 PM
Some of them are taking a few decades getting to the point of breaking down.

Or people just live with it til they no longer can.

Just because a system was installed poorly doesn't mean that the owners will have it fixed. My neighbor drives that point home
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