Water Works!!

Forum about flow calculators available on pipeflowcalculations.com and how to find solution for your fluid flow problem.
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rachapman
Posts: 2
Joined: Tue Mar 15, 2011 9:06 pm

Water Works!!

Post by rachapman »

Hello,

My name is Alex. I am a Doctor specialising in urology, so flow is a very important topic in my line of work!

I have been asking a question to which I have not been able to find an answer.

During bladder and prostate operations we use something called a resectoscope. It has a telescope and light source, but also a continuous irrigation system to wash out the blood stained fluid that obscures the view. Now, the inflow is normally a bag of water placed 1m above the patient. The outflow tap is on the side of the resectoscope. Good drainage not only gives better views but keeps the bladder pressure down which reduces complications

Would we achieve better drainage with tubing on this outflow tap going down to the floor to give a column of water which would give a bigger pressure difference, or would the length cause increased resistance and thus decrease the flow? The internal diameter of the tubing is 4mm, although the inflow and outflow channels within the scope is smaller.

Any advice would be appreciated
Alex
admin
Site Admin
Posts: 380
Joined: Mon Feb 08, 2010 7:47 pm

Re: Water Works!!

Post by admin »

If you keep the same pipe length and increase the water column height, you will have better flow rate.

But ,if you increase water column and pipe length in the same ratio, you will not get better flow rate.

Here you have equation to see relation between pressure drop, flow rate and pipe length. If you increase water column (pressure drop) two times and also length two times - flow rate will not change.
http://www.pipeflowcalculations.com/pip ... fluids.php
Pipe flow calculations - since 2000
rachapman
Posts: 2
Joined: Tue Mar 15, 2011 9:06 pm

Re: Water Works!!

Post by rachapman »

The only way to increase the column of water is to use the tubing which in turn will add to the the length. Are you saying that the two cancel each other out, the extra length will give a larger column and bigger pressure difference, but the length will add resistance. Are they proportional and inversely proportional respectively to flow rate to the same degree? The way i was thinking was, if you wanted to syphon a collection of fluid, then the longer the tube the better (more height), but you are saying the effects will be the same what ever the length because of the inversely proportional effect of the length?

Sorry to ask you to spell it out!
admin
Site Admin
Posts: 380
Joined: Mon Feb 08, 2010 7:47 pm

Re: Water Works!!

Post by admin »

Yes
Pipe flow calculations - since 2000
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