PDA

View Full Version : Low Head Drainage and Check Valves


csmlawn
08-13-2008, 09:35 AM
When you have a hill type grade and the lowest head on the zone doesn't go down all the way when it shuts off and drains until there is no water left in the pipe, does that mean there is no check valve in the head?

FYI... All other heads in the zone go down and no water comes out.

Thanks.

Kiril
08-13-2008, 10:03 AM
What is the elevation change?

If you want to know if the head has a check, then pull the head and "check". ;)

Waterit
08-13-2008, 10:07 AM
When you have a hill type grade and the lowest head on the zone doesn't go down all the way when it shuts off and drains until there is no water left in the pipe, does that mean there is no check valve in the head?

FYI... All other heads in the zone go down and no water comes out.

Thanks.

A successful diagnosis. You are a sprinkler man!

csmlawn
08-13-2008, 01:08 PM
LOL!!! I don't even know what one looks like... anyone have any pics? I've pulled two heads to examine, but the cap screw was on so tight on both I couldn't check them. According to WM, the T3 rotor comes with a check valve... However, my low heads piss like racing horses. The elevation change is about 6 feet (if that).

BrandonV
08-13-2008, 01:12 PM
depends on the amount of head. I know that the pro sprays we use will only hold back 10' of head you might need to install an online check valve.

Mike Leary
08-13-2008, 02:13 PM
depends on the amount of head. I know that the pro sprays we use will only hold back 10' of head you might need to install an online check valve.

Beep beep..warning: the inline check valves eat pressure for breakfast.
The more head you need to adjust for, the higher the psi loss.

csmlawn
08-15-2008, 02:29 PM
Beep beep..warning: the inline check valves eat pressure for breakfast.
The more head you need to adjust for, the higher the psi loss.

Hi Mike,

Can you explain more on this?

Mike Leary
08-15-2008, 02:51 PM
Hi Mike,
Can you explain more on this?

The Hunter low-drain check valve is adjustable from 4' to 32'. As the height
increases, the friction loss does also. It is factory set for 12' with a friction
loss of 7 psi. With 32' of height, the loss is 15 psi, so you can see the need
to be very careful adjusting it just enough to prevent low drainage. The amount
of loss is also tied to your gpm, and the loss can screw you.

Mike Leary
08-15-2008, 03:02 PM
www.hunterindustries.com/resources/pdfs/instructions/domestic/23561w.pdf

irritation
08-15-2008, 03:22 PM
Where's your friction loss data?

Mike Leary
08-15-2008, 03:30 PM
www.hunterindustries.com/products/miscellaneous/hcvintro.html

irritation
08-15-2008, 03:35 PM
Thank you. :)

Mike Leary
08-15-2008, 03:59 PM
We had trouble breaking the ldcs when they were buried under a riser, even with Marlex
and swing joints. Solved by adjusting it on the vertical then turning it horizontal with
double Marlex.

irritation
08-15-2008, 04:08 PM
I would never use one. Spent 4 hours searching for a pipe restriction once and found a inline check valve clogged with debris and was not even close to a sprinkler head. :hammerhead:

Mike Leary
08-15-2008, 04:15 PM
I would never use one. Spent 4 hours searching for a pipe restriction once and found a inline check valve clogged with debris and was not even close to a sprinkler head. :hammerhead:

Prolly debris from a break that someone did not flush properly, being so
flat in your area, I would doubt you need them much.