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  #1  
Old 06-09-2011, 05:33 PM
anotherbrian anotherbrian is offline
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Measuring Dynamic Pressure at the Spray Head

How do you measure dynamic pressure at the spray head?

I have a PVC T connector with a pressure meter hung off the T.

I can place it in line with the sprayer:

Sprayer
||=Meter
|| <-- supply

Thus, this allows the sprayer to function. The measurement is made while the sprayer is
spraying.

Alternately, I can plug the end of connector and use it to replace the sprayer.

Plug
||=Meter
|| <--supply

Which of these measurements would be considered the dynamic pressure at the head?

Is that the measurement that would correspond to the pressure listed in the performance specs of the sprayer (e.g., Number 12 full sprayer shows 9 foot radius at 15 psi, 10 feet at 20 psi, 11 feet at 25 psi, and 12 feet at 30 psi).
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Old 06-09-2011, 05:38 PM
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Wet_Boots Wet_Boots is online now
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the first, but I always shake my head at these measurings, because systems should never be designed so that you ever need these measurements
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Old 06-09-2011, 08:18 PM
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Mike Leary Mike Leary is online now
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When I was starting out, I bought a kit with a gauge and adapters for RB & Toro heads. It even included a pitot adapter for impacts. All I learned was the dead plants and the turf stressing were caused by a piss-poor design. I threw away the kit years ago.
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Old 06-09-2011, 08:30 PM
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hoskm01 hoskm01 is offline
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Dynamic=working
Static=pressurized, no flow.
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Old 06-09-2011, 08:30 PM
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Inspired Inspired is offline
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It should look like my avatar
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Old 06-09-2011, 10:41 PM
anotherbrian anotherbrian is offline
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Thanks!

Mine too - piss poor design. I am making a study of it before making changes. I haven't worked out the calculations yet as to pressure losses based on pipes and valves, but I should have that done by tomorrow.

Because I am on city water, I can measure my flow rate. And now I can measure the pressure at the spray head.

I measure 22 gpm going into a zone which has 6 half sprayers (number 12H) and 5 full sprayers (number 12H). Assuming all that water makes it to those sprayers, that works out, on average, to be 2.8 gpm for the fulls and 1.4 gpm for the halves.

But I measure only 17 psi at the spray head (and they all shoot out rather poorly). According to the # 12 product literature, a 20 psi (which I am not obtaining) uses 2.1 gpm for the full and 1.05 for the half. So working out the calculation, of the 22 gpm going through the city's meter, I am missing at least 5.75 gallons. Where did it go?

I am suspecting that all that missing water is leaking out of the hydro index valve into other zones and dribbling out their spray heads.
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Old 06-09-2011, 10:43 PM
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Mike Leary Mike Leary is online now
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Quote:
Originally Posted by Inspired View Post
It should look like my avatar
You don't need a gauge to tell a client they're screwed.
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Old 06-10-2011, 08:05 AM
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mitchgo mitchgo is offline
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shut off all the heads and start looking for a break
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  #9  
Old 06-10-2011, 09:05 AM
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FIMCO-MEISTER FIMCO-MEISTER is offline
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Quote:
Originally Posted by anotherbrian View Post

I am suspecting that all that missing water is leaking out of the hydro index valve into other zones and dribbling out their spray heads.
Seen that happen. Get rid of the hydro indexing valve whether its the problem or not. Will make your troubleshooting a whole lot easier.
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Old 06-10-2011, 09:26 AM
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Wet_Boots Wet_Boots is online now
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a traitor to your user name....
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