head for cracked valve

[JMorris271]

Hi RC.
When adding up the head for the plumbing lines, how is the closing down a gate or a ball valve computed since doing so is bound to changes that value. If you don't know it's exactn position , how is that figured?
I am trying to figure out what my total flow is in the tank.
Thanks

 

[fishgate]

If you can direct the drain valve to a bucket with a line drawn for 1 gallon, set your timer and see how long it takes to fill it. This assumes your return section can continue to flow being down a gallon. You could always dump an extra gallon in before you start. Not terribly scientific but should get you close.

 

[Sk8r]

Maybe I'm wrong-headed, but I've always reckoned that if I insert a gate valve (discounting the bump of irregularity in the joint) and close it 50%, that I have blocked 50% of the flow measured at the 'out' end, whatever it used to be.

 

[billdogg]

Maybe I'm wrong-headed, but I've always reckoned that if I insert a gate valve (discounting the bump of irregularity in the joint) and close it 50%, that I have blocked 50% of the flow measured at the 'out' end, whatever it used to be.

I'm with Sk8r on this one. When I figure out in-tank flow I pretty much discount the return anyway, or just sorta take a guess.

 

[JMorris271]

Maybe I'm wrong-headed, but I've always reckoned that if I insert a gate valve (discounting the bump of irregularity in the joint) and close it 50%, that I have blocked 50% of the flow measured at the 'out' end, whatever it used to be.

Would it be proximal to count the turns possible on a valve , whole or in part,and divide that number by 2 to determine where the 50% , by 4 for a 25%ect. flow rate through that valve would be.
With a pump that has a flow rate of 2000 gph and you shut the valve 50%, is it correct that you can assume you are getting 1000 gph minus any other head loss involved. I am trying to factor the head loss and gallons lost to a common denominator.
What can be done if the degree a valve is opened is unknown other than guestimate to compute total flow?:blown: