Surge Tank Sizing 3

[Physics_Nerd]

Hi Guys

I am currently working on a pump Station for which I need to size a surge tank for Water Hammer/pressure variations, I know that we have some standards in AWWA m11 but if u guys have anything like an excel sheet or anything please help me out this is the first time I am sizing a surge tank

I've done expansion tanks for Air Conditioning Systems and Pressure tanks for VFD-Booster Pumps but here we are talking abt a pump station with really high flow like 5000 m3/hr and basically I need to size a surge tank please help me out even if u know any analysis software or manual calculations etc

 

[EmmanuelTop]

Check AFT Impulse at

http://www.aft.com/products/impulse

The software is ideal for surge analysis in 100% liquid systems. Quarterly lease cost for a standalone license was about 1,800 USD the last time I checked.



Dejan IVANOVIC
Process Engineer, MSChE

 

[Physics_Nerd]

Thanks Man I ll definitely Check the software if my company is willing to pay for it, you see we dont really have a big project like its just one pump station we dont have an entire site so I have to only size just this one tank do u know any manual calculations??? but I ll try to convince the company to buy the software anyway

 

[LittleInch]

First off work out the scenarios as to why you need to have such a valve and tank.

Without working this out first you won't be able decide whether your tank is 10/20/50/100 m3 or indeed that you don't need one.

Without a transient simulation of some kind, there is no real means to determine whether such an event occurs or how much fluid you need to take out of the system to prevent over pressure.

5000m3/hr is a decent flow and pipe size so the tank size might be quite a reasonable size, or it could be nothing,

If you don't want to spend the time get a flow consultant to run some numbers for you.

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

 

[bimr]

You can do this with KYPipe.

http://kypipe.com/node/392

http://kypipe.com/new_stuff/6.165.9.shock and water hammer loading.pdf

https://www.engineersaustralia.org....Pressure Surge Damage in Pipeline Systems.pdf

 

[georgeverghese]

A surge tank may not be necessary if you can setup a damped check valve downstream of each of the pumps and / or a slow closing downstream shutdown valve.

 

[BigInch]

5000 m3/h flow, I'd guess that you will need a surge tank, or have real good, proven reasons why you would not. I don't think some XL sheet that somebody on the internet gives you will be up to it.

I'd also suggest that you take your little budget and hire a consultant that can factor a week of software time into the tiny bill. That will probably be a far more efficient price and you'll get some very badly needed expertise as well.

 

[Physics_Nerd]

Thanks folks!!! that was very helpful

 

[Physics_Nerd]

I ll talk to my Manager about the software or to hire the consultant

 

[BigInch]

If you have a limited budget, it will be cheaper to hire a consultant. Otherwise you will spend more (1) on all the time yourself learning how to use the program and (2) trying to find out if the software is giving you reasonable answers, if you made an input error, or if you are simply interpreting the output correctly. And you might still need to convince your client that you have the necessary expertise to use it and make a design from it. If you only expect to do these kinds of projects once in awhile, or maybe never again, then there isn't much sense learning to be a transient hydraulics engineering specialist.

 

[LittleInch]

I'm more concerned about the fact that you think a surge tank is needed before you've actually finalised the design and operating system.

The aim should be to avoid having such a tank, not rely on what is effectively a pressure relief valve going off every time you stop the pipeline.

Pressure surges sufficient to exceed the design pressure + 10% on a regular basis are not normally a good news long term and results in fatigue, movement of pipes especially at bends.

You may end up with a very occasional situation where you need one, but it should be the exception rather than the rule IMHO.

That's why you need to see why and where you get high surge pressures and what you can do to reduce it so that you don't need a surge relief tank. That tank will then need emptying before you can start again to give you ullage in operation.

The design of large water pipelines may be different, but it doesn't sound like a good move to me.

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

 

[Physics_Nerd]

I understand what you are saying but the thing is I have seen the pump station built by the other contractor who basically has the entire site and they used a Surge Tank for their System and it seems like the client wants us also to install the Surge Tank unless we can prove with references and computerized reports that they dont need a surge tank

My manager says that he dont wanna take responsibility for the sizing of this surge tank, I mean if we ask the company to buy a software then its really on our head like its gonna be on my head in particular, I believe I ll tell em to hire a consultant

 

[Physics_Nerd]

I also checked with some suppliers if they can suggest the size of the surge tank and it seems like they dont know

Guys do you know any manufacturers of really huge surge tanks for domestic water applications please share here so that I can contact em not particularly for calculations but at least to know if they have the tanks available.... here many companies I contacted they dont have the thing available

 

[BigInch]

Start with scaling. It may have no relation, but you might try. What's the flow rate of the other pump station and how big is that surge tank?

 

[KevinNZ]

I agree with BigInch and look at getting a consultant to model your system. We have installed a number of large pump stations and none have needed tanks. The model would include pump momentum and other effects that may reduce the need for a tank.

 

[Physics_Nerd]

What I have exactly is a sort of distrebution plant there is one inlet from saline water conversion plant and then water is stored in huge storage tanks and we got like 3 outlets from tanks two of em are directly going out of the site toward the city and one of em follows rather a long route but then again it goes out toward the city so thats about it, they need booster pumps here becouse its a long pipeine and there is only one pump station here but I went to the other site of the same customer and there they had one pump station with like 1.75 times our flow rate so I already did the scaling to get an Idea abt the Tank size but u know it does not work that way and we know it seems like I've found some company who can do this transient analysis lets see......

BTW KevinNZ did u do the transient analysis??? plaese help me learn it if u know

 

[Physics_Nerd]

@BigInch man I wrote on my notebook but its on my work station I ll let you know once I get to the office

 

[LittleInch]

Physics Nerd

I am glad you are trying to get a consultant to work with you as it doesn't appear your really understand why you might need surge tanks and what the key issues are.

I sense English isn't your first language, but if you want to come over as a serious engineer, please avoid text talk and use proper words, e.g.

them not "em"
Want to not "wanna"
Going to be not "gonna"

Use engineering data - you're an engineer so act like one - not "huge", "big", etc.
My "huge tank" is 160,000 m3. I doubt your "huge" tank is so big...

We also don't know where you are (region, country) so its difficult for anyone to provide such advise.


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

 

[BigInch]

If a tank is needed, all high pressures should be dissipated within 15 minutes.
Then for estimating purposes only:
Volume of 15 minutes of your flow rate is,
5000m3/h 15/60 = 1250 m3

You will most likely need a tank as long as your pipe diameter is small and velocities are above 5m/s

If you can increase pipe diameter and get velocity below 1m/s, you might not have any surge problem at all.

 

[Physics_Nerd]

I having 1m/s in the header however we have like 1.75 m/s in the pump discharge so we dont have too much speed


@BigInch Man I am attaching a picture here, Please tell me what things do I need to size the surge chamber/expansion tank/air tank