Flow increase in 6" Line

[RJB32482]

We currently have a 6" water line that goes underground and splits into 2 different 6" water lines that never tie together again. We are looking at blanking one of these 6" water lines due to not using the water at the source anymore.

Am I incorrect stating that the flow in the other 6" water line that will still be used go up? My thought would be that it would be less that double.

Please advise. Thanks.

 

[ash9144]

If you aren't using water at one branch there is no flow through that branch. So no your flow in other branch will not go up. If the unused branch is open and flowing and you blind it then you will have slightly higher pressure at the branch and possibly an increase in flow. But since it is 6" supply header probably not much increase.

 

[JJPellin]

There is not enough information to answer this question. Is this a centrifugal pump? Is this process flow, level or pressure controlled? What is the relative length of the common 6" header as compared to the individual 6" branches? What is at the other end of these lines? Are these pumping to open atmosphere, to a constant pressure system, to a system with back-pressure that varies over time?

Take a garden hose and install a Tee fitting at the end. Attach two hoses to the TEE and run those two hoses to two different parts of your garden. When you block in the end of one of those hoses, the flow coming from the other one will go up. But, it will definitely not double in flow. You need to model the system and calculate the pressure drop in each leg and apply that back to the discharge of the pump.


Johnny Pellin

 

[RJB32482]

Thanks for the replies.

This water line comes from a treated water pump down at the other end of the plant. There are man users before it comes down all the way to our side of the plant. The modeling would be difficult.

I was going to take some flow rates with a portable flowmeter and see what the flow was on both of the lines currently with all users. So just wanted to make the point to others that if we removed the other line from treated water service, the flow in the other 6" line would increase and actually give more flow to the users that would be on the other branch.

Thanks.

 

[chief]

The recommended flow velocity for a 6" steel pipe is max 10ft/sec. This prevents premature erosion of the pipe. The advised max flow rate for a 6" pipe is in the region of a 1000 gpm.

Offshore Engineering&Design

 

[alisaffari]

Hi experts
we can increase flow rate in pipe, but we shall consider economic consequence.
for example economic velocity in 6" pipe is about 1.766 m/s.
in higher velocity, pressure drop (according to it's cost) and erosion shall be consider.

i apologize for my English language.
thanks
saffari