Horizontal sand filter crack\burst !

Jump to latest Follow Reply
You have to remember that there are over 300 gallons per minute going through each filter and set of pipes. If you suddenly close one valve, then you are stopping all of that water, which will cause a pressure wave to reflect off of the valve and you are forcing it into the other tank. Closing one valve is not as bad as closing both, but it's still bad.

What is the filter pressure now that all of the water is only going through one filter?

I think that the indentation and scratch are close enough to the crack to possibly be related. If it created a defect, the defect could have propagated as the filter was repeatedly pressurized and unpressurized.
 
I see this thread is a few months old but, but stumbled upon it over the net, and figured I'd jump in.


It is highly unlikely this damage is a result of water hammer. Normally water hammer events manifest themselves in regards to filtration equipment in very specific ways. Normally the external manifold/valving is damaged, or the overdrain/diffuser is blown off. Also, if a the pump is left to run in the midst of a backwash initiation, a few laterals/collectors can be blown out, filling the pool with sand.

I am very familiar with these Nemato filters, as I work for a competing manufacturer. We build FRP filters just like these, and in 13 years, never have I seen a crack like that in a sidewall from a water hammer event. It is an industry standard (Most Follow it) to use a 4:1 safety factor when calculating shell/knuckle/head thickness on a pressure vessel. That means that filter would realistically need to see 300-400 PSI before it burst.

Water hammer may very well have aided in the damage, but it is doubtful it was the root cause. By the looks of the picture, the glass is ''wetted out''. In my opinion, the vessel most likely developed a stress crack for whatever reason, and it allowed water to seep into the glass layers causing them to essentially rot and weaken. Those filters have a vinylester liner on the interior that protects the glass layers, if it fails, Bye Bye sand filter.....


Hopefully you have gotten the situation rectified by now. Best of luck.
 
MFL,

Thanks for chiming in, even if the post is a little old. We all hope you will stick around and post frequently.......filters are often discussed here and your expertise is welcome. :-D
 
By all means, chime in anytime !
We are scheduled to have the filter replaced next week on the 20th. I was hoping to at least talk to the installers to get their opinion. The manufacture suggested only replacing the one, as they have never seen it before, Nemato is just a few miles from me.

Thank you so much for the informative post, I also did not believe this was the weakest link in the system.
 
The odds of that crack just happening to form where it is most vulnerable to external contact are too high. If it wasn't hit with the bolt I imagine someone braced something on top of those cross members. Maybe they were tightening a fitting, cutting a board, hammering something, who knows, but the location of that crack just screams "external blunt trauma" to me.
 
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply