Seeking advice on calculating the required pump size for a hydro test on a coil system

[tru_go]

I'm conducting a hydro test on a coil system and need guidance on determining the appropriate pump size. The objective is to pump water through the coil with a flow rate sufficient to eliminate air pockets that tend to form at the top of the coil (see yellow in image below).

Here are the essential details about the coil:

The inlet and outlet of the coil are at the same height, 1 meter off the ground.
Outer Diameter of the pipe: 75mm
Inner Diameter of the pipe: 70mm
Diameter of the coil: 1m
Length of the coil: 3m

Based on a simulation, it's evident that a sufficiently high flow rate can remove all the air from the system. Can anyone advise on how to calculate the required flow rate to achieve this goal? I also want to ensure that the coil remains entirely filled with water throughout the process. Any insights on making this calculation better and more concise are welcome. Thank you!

 

[pierreick]

Hi,
Look for hand pump to perform hydraulic test using your favorite search engine!
Very basic requirement unless I missed something.
Pierre

 

[tru_go]

The hand pump will take too long to compress all the air with all the water in the coil. Removing as much air as possible before using the hand pump will make it easier and faster.

 

[LittleInch]

You simply need to generate a flow velocity of >1m/sec.

This works even when pumping vertically down with air in the system.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

Remove all the air. You will know air is present by the rates of pressure build. If its not nearly instantaneous, you've got air. Start over. Remove all air.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[tru_go]

LittleInch - Do you mind please explaining this in more detail?

 

[tru_go]

1503-44 Yes, you are correct. However, I will have to purchase a pump that is strong enough to get the job done while also managing the cost of the pump. Therefore, I need to know that what I am purchasing is good enough.

 

[LittleInch]

There are some theoretical papers somewhere which calculate the speed of liquid flow, angle of a pipe and a gas bubble which is trying to go in the opposite direction to the flow.

When you stick in water and air and 90 degrees, the answer comes out to just less than 1m/sec. i.e. it will force air vertically down a pipe when there is flow going down at >1m/sec

Sometimes people just state this as a rule of thumb, but that's where it comes from.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[tru_go]

I will have a look into it. Thank you LittleInch

 

[pierreick]

Hi,
You may find pointers in this document:

https://eprints.hrwallingford.com/545/1/Air-problems-in-pipelines.pdf

Good luck
Pierre

 

[LittleInch]

Looks pretty similar to this one also.

So bigger pipes have a higher velocity than smaller, so maybe need higher velocities than 1m/sec, but not more than 2.

I tend to deal with smaller pipes in the 500-750mm range usually so just use a min of 1m/sec.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.