Discharging into full inspection chamber / manhole.

[ldavison10]

Hi,
Has anyone come across what effect discharging a full bore pipe into an already full (of rainwater) inspection chamber has on the discharge rate.

Im assuming it depends on the size of the inspection chamber, how deep the pipe is submerged and what the head of water is driving the pipe.

Any help appreciated.

Kind Regards

Lee

 

[BigInch]

Lifts the manhole cover off.

I have not failed. I've just found 10,000 ways that won't work."-Edison “If Edison had a needle to find in a haystack, he would proceed at once to examine straw after straw until he found the object of his search. I was a sorry witness of such doings, knowing that a little theory and calculation would have saved 90% of his work.- Tesla

 

[ldavison10]

And what if its sealed down?

 

[BigInch]

pressure increases

I have not failed. I've just found 10,000 ways that won't work."-Edison “If Edison had a needle to find in a haystack, he would proceed at once to examine straw after straw until he found the object of his search. I was a sorry witness of such doings, knowing that a little theory and calculation would have saved 90% of his work.- Tesla

 

[quark]

If the lid is leak proof, you will have problems draining the pipe, where ever you place it. When you say the chamber is full, do you mean there is restriction to the flow downstream?

 

[katmar]

The volume of the chamber and the depth of the inlet pipe will have no impact on the discharge rate if the chamber is already full. Only the backup in the inlet pipe (i.e. inlet pressure) will impact on the discharge rate.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[ldavison10]

Imagine the discharging pipe is throwing out more water than the underground drains can handle. The water is just not flowing away fast enough, is starting to fill the chamber and submerge the discharge pipe.
Is there a way to measure how soon the water will start to back up to roof level, therefore risking water ingress to the building?
Would that happen or would the pressure of the water force the underground drains to run at a higher velocity?

Thanks
Lee

 

[katmar]

If the inspection chamber is sealed it is just a part of the pipe. If the drains cannot take the water away fast enough the water will back up towards roof level. As it backs up it will increase the driving force and the water will flow faster in the drain. It is not possible to say whether it will flood the droppers from the roof without doing a detailed analysis, but every drainage system has a maximum capacity and if you go over that you will get flooding.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com