Technical question about sand filter

[duraleigh]

On my Triton TR-140, I have a (roughly) 1/4 black hose that is inside the filter touching the filter top. The bottom of that hose is buried in the sand and connects to the center pipe from the laterals to the pool. Triton refers to it as an "air relief tube" or an "automatic air vent".

I do not understand the function of that tube. I assume it is not absolutely essential as it could be fairly easily submersed in the water in the filter and blocked completely. Any ideas?

 

[PoolGuyNJ]

I think it's a hold over from the old Pac-Fab days when the top was clear. The air can then be bled off for a more responsive tank pressure reading.

Scott

 

[duraleigh]

I still can't quite picture what it does. Since it's connected to the return pipe, it has to send water back to the top of the filter when the pump is running. Is it's purpose to help evacuate air out of the top of the filter?

 

[mas985]

It allows air in the filter to exit the filter. Too much air within the filter can cause some series problems. Least of which is blowing the tops off of skimmers and pump baskets.

Air can exit the filter because the pressure at the top of the filter is much higher than the pressure where the tube connects to the return pipe. This is because of the head loss in the water as it travels through the sand and exit plumbing. So air will travel down the tube and out the returns. I have one of these in my cartridge filter.

 

[duraleigh]

Air can exit the filter because the pressure at the top of the filter is much higher than the pressure where the tube connects to the return pipe.

Cha-ching! :lol: That makes perfect sense. I had my mind convinced that the flow direction thru the tube was opposite. Now it's function is very clear! Thanks!

 

[mas985]

Also, I forgot to post this although you probably have already seen it.

Exploding Filter

 

[waste]

I hate newbie questions :lol:

 

[New2Me]

I have this Baker Hydro Baker II filter - http://www.poolcenter.com/parts_filter_ ... I_1984.htm -that FOXXX pools re-branded as theirs. I too wondered about the purpose of the little tube(or hose) poking up to the top. I also wondered if it mattered that the little "BakerHydro screen, air relief"(item 5 on the link) on the top of it was damaged,and missing the end (it was open at the top.) After continually finding debris in the ECG inlet filter screen (usually small lightweight things) I took apart the MPV to check for a bad spider gasket; it was fine. Then I finally realized that lightweight stuff was floating to the top of the filter, passing through the missing end of the screen, down the tube past sand filter bed, and out to lodge in the ECG filter screen! A new screen stopped that problem.