Anti vortex plate

[nabeel3]

Dear All
Attached is the picture of anti vortex plate in the suction of fire pump line which is inside water tank. Is this acceptable.

 

[LittleInch]

Looks good to me.

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

 

[LCREP]

No the photo does not meet NFPA 22 , 2013 edition section 14.2.13 ...the assembly shall consist of a horizontal steel plate at least twice the diameter of the pipe with a minimum of 6” above the bottom of the tank. It goes on to indicate must be attached to an 90 degree elbow, the index provides a detailed diagram of the anti vortex plate. This has been a requirement of NFPA 22 for at least 30 years. But I have encountered anti vortex plates you have photographed several times on existing tanks during the 5 year internal tank inspection as per NFPA 25. Also have found the anti vortex plate deteriorated over time and had to be replaced.

 

[nabeel3]

Thank you for the reply. This tank is a combined potable water and fire water tank, which is used to store potable water in a RO plant

 

[MJCronin]

I believe that there should be a brief discussion on types vortex breakers here...

What "nabeel3" has pictured in his question is a perfectly acceptable "X type" device for pump protection in the process industry, where pump suction must be taken from a relatively small volume,..... a potable water tank.

The process industry has NO SPECIFIC DIMENSIONAL GUIDELINE to determine the configuration of a VB, like for example the ASME Dimensional codes for piping flanges. There are only company developed "rules of thumb and recollections of Geezers. Some companies have "pancake" cross, single plate and other configurations

There have been many discussions on this fora on Process System Vortex Breakers

https://www.eng-tips.com/viewthread.cfm?qid=434029

https://www.eng-tips.com/viewthread.cfm?qid=78114

https://www.eng-tips.com/viewthread.cfm?qid=268143

There are also guidelines in the "Hydraulic institute Standards" on Vortex Breaker and Sump Configurations.

Now we come to the NFPA Requirements ..

NFPA 20 and 22 discuss particular types of "donut" or "pancake" VB ...... BUT BOTH STANDARDS ASSUME THAT THE SUMP/TANK IS LARGE, QUIET and a MINIMUM SUBMERGENCE IS MAINTAINED.

Some Alternative design examples are here: .......

https://www.fps-eg.com/2019/06/anti-vortex-plate-according-to-nfpa-20.html

Will these work in all circumstances, I do not know....

But I do know that it would probably be wise to distinguish between a "process system vortex breaker design " and an "NFPA Vortex breaker design"

Anyone have anything to add here ????

MJCronin
Sr. Process Engineer

 

[LCREP]

The vortex design in the photo I have run into in the electric power industry where the tank is used for process water and fire protection. The dozen or so times I have encountered they all did not meet NFPA 22. These were tanks that were new up to 20 years old. To say the least site management was not happy when I brought this “recommendation to update to NFPA 22” to the underwriter attention. When you $300-500 million $$ at risk you get have some serious discussion on “recommendations”. Most if not all plants were not on public water supply and had at least two 2000-2500 gpm fire pumps connected to the tank, or 2 tanks with separate fire pumps...oh the joy of power plants...lol.

 

[MJCronin]

I take strong issue with your description of "“recommendation to update to NFPA 22” .....

The correct design of "vortex breakers" is closer to a branch of voodoo than anything else

MJCronin
Sr. Process Engineer

 

[LCREP]

MJ

Why not propose a change to the NFPA 22 committee regarding anti vortex design?? Until changes to NFPA 22 and Factory Mutual Data Sheet 3-2 occurs the insurance industry will continue to make “recommendations” for non compliant installations.

I spent 36 years with a property insurance carrier as a Risk Engineer to give you my point of view.