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Steve E

New Member

1

Friday, May 11th 2012, 9:05am

velocity question

Recently, I was at at a property where the maintenance man had reduced the source flow by closing the ball valve about half or so. He said that the high pressure was causing trouble with his toilets etc. My sprinkler is fed from this same (closed) valve and has always been a little weak. My question is about what is really going on when you do this. I think I understand the concept of increasing velocity through a restriction, but this has me wondering about handling high pressure this way. When you turn down a flow control valve handle to reduce fogging, is it the same as this? It may just be a coincidence but I reduced the flow at a DCV on another system I maintained and it split the valve on the next cycle. Did I increase the velocity to the point that it caused the damage? I replaced that valve and left the DCV full open for now. I would appreciate any help on understanding this.

Wet_Boots

Supreme Member

Posts: 4,030

Location: Metro NYC

2

Friday, May 11th 2012, 8:13pm

a pressure reducer needs to go into the feed to the house, and the sprinkler system should get unrestricted pressure

a partially-shut ball valve is a problem waiting to happen

Steve E

New Member

3

Saturday, May 12th 2012, 11:30am

Thanks for the response. Am I correct in thinking the split valve was caused by me reducing the flow and there by increasing the velocity past the safe limits. This particular system has 98 static and is constantly splitting heads (rotors and sprays) at the threads. I cannot get the management to authorize a regulator, I just keep replacing heads every month or so. What makes things worse now, is the duty cycle has increased due to cycle soak programming (we have water restrictions). So I'm afraid that the time between replacements due to failure will be shorter now due to the three start program. That's why I did that to the DCV, trying anything to slow the constant head failure. I guess I don't understand the difference between slowing the flow in a flow control valve and partially closing a ball valve. I'm really just trying to do the best thing for my customers, but I don't want to cause more trouble by doing the wrong thing. If closing a ball valve is the wrong approach I need to know. I'll need facts so I can sell them on the idea that what they are doing is not the way to handle this excessive pressure. Sorry to be so thick about this, I'm trying to understand what is really happening in this case. Any help is appreciated.

Wet_Boots

Supreme Member

Posts: 4,030

Location: Metro NYC

4

Saturday, May 12th 2012, 11:39am

Unless the maintenance man writes his own paychecks, there is someone over his head that can require that a proper pressure regulator(s) be installed.

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