Messages

1

Irrigation / Downhill water hammer

« on: May 20, 2015, 09:15:57 PM »

Cary, I was just reading the thread about the golf course irrigation where most of the holes are downhill from the pumping station.  You mentioned that problem that the water wants to keep flowing down when the sprinklers turn off, and what can be done to mitigate that.

I'm seeing something similar I think, I have a 3HP Sta-rite DHJ at the edge of a lake.  The furthest zone is 700ft away and seems to be about 20 ft elevation change.  When the pump turns off (via relay from timer) I hear a clunk clunk from the flapper valve right in the intake flange of the pump. 

I'm assuming this is water hammer from water reversing direction, is there a good way to stop this?

2

Valve Tech / Any plans for a cheaper 2inch CSV version of plastic?

« on: November 23, 2013, 10:29:10 AM »

I have a large yard (>3 acres) with 75% grass bordering a lake (and is used for watering)

I have installed the beginning of an irrigation system, a 3HP pump with a 2 inch discharge. 

My first two irrigation zones are running about 55GPM.  I see the 1.25 CSV but I really would rather not choke down the 2" to 11/4".  Reason why is because in a balanced system where the pressure is basically equal on both sides, the water velocity within the valve would have to increase to keep up... and I'm thinking that would produce a lot more wear on the valve body itself right?

So the main question is, is there plans for a 2 inch version of the plastic CSV, mainly targetted for residential "large area" minus the additional feature of adjustable pressure points?

EDIT: Just realized I had posted a similar question in the Irrigation topic a while ago...
http://cyclestopvalves.com/smf/index.php?topic=1889.0

3

Irrigation / CSV recommendation for ~55GPM zones and 2" piping

« on: July 30, 2013, 12:18:19 AM »

So first off I have installed several zones on a large acreage yard that run about 50-55 GPM.  I have a Sta-rite D-series 3HP pump, currently just running manual on/off via circuit breaker.  There's 2" hunter PGV valves but manually operated at the moment.  The zones are working nice, but there's more to do.

The 50GPM CSV model seems just out of reach for that scenario, but I'm concerned about the price of the 2" versions, where the price is just about more than I'd really like to spend.  So let's entertain the idea of the 1.25" version for a moment.

I was also thinking though, doesn't reducing the size of the pipe from 2" to 1.25" cause a high velocity flow problem through the CSV?  WHen I look at water velocity tables from http://www.engineeringtoolbox.com/pvc-pipes-friction-loss-d_802.html , for 2" PVC sch40 pipe, its about 4.9 ft/sec.  When you go over to 1.25" pipe, that jumps to 11.1 ft/sec and a head loss of 30 ft/100ft and friction loss of 13.2psi/100ft...

Now I can slightly modify the system to drop down a bit in GPM per zone by adding a new zone in the middle of the backyard and redistributing the heads a little. But my original thought remains where I question putting a 1.25" device on 2" pipe.

Is my concern unwarranted?

And second, I wonder if redistributing the zones to have less GPM would be better?