Amtrol Multi-Dome feature of Well-x-trol and Champion pressure tanks

[Reach4]

Amtrol Well-x-trol and Champion pressure tanks have a feature called Multi-Dome construction. Shown as item 4 in the picture below, the dome above the diaphragm will prevent the diaphragm from stretching too much if you put in too much pressure. That seems like a really nice feature. It also serves as an internal strengthening brace. The picture below shows a second inside dome being used just as a strengthening brace.

The "Water Worker" tanks do not have this feature as far as I can tell. Well-x-trol have a Butyl diaphragm, and is rated for higher pressures. The Champion tanks have a Butyl/EPDM diaphragm. That will not hold precharge air air as well as the straight butyl.

 

[Valveman]

Many tall and skinny tanks have a dome to prevent the diaphragm from over-stretching. This is good and bad. Yes it prevents the diaphragm from over-stretching, but this only happens when the air charge is lower than it should be. And when the diaphragm hits the dome, it acts like a waterlogged tank and the pressure spikes instantly. So the dome keeps the tank from being able to utilize any air in a low pre-charge condition.

 

[Sponsor]

 

[PumpMd]

I could say many things about this video but I just want to show everyone how WellXtrol makes their tanks. Notice how it's a WM-9 I would say and they replace it with a WX-251

 

[Reach4]

A follow-up: I came to realize that an effect of multi-dome construction would be that you would get a short-cycling symptom if the precharge is very low. The diaphragm would be sitting near the dome and would be restricted in how far the diaphragm could expand. That should save the tank.

It makes sense now, but I did not think of that symptoms earlier.

 

[Midriller]

Many tall and skinny tanks have a dome to prevent the diaphragm from over-stretching. This is good and bad. Yes it prevents the diaphragm from over-stretching, but this only happens when the air charge is lower than it should be. And when the diaphragm hits the dome, it acts like a waterlogged tank and the pressure spikes instantly. So the dome keeps the tank from being able to utilize any air in a low pre-charge condition.

Yep they do this as an alert to call for service or that you air your tank up. A diaphragm tank can only stretch so far before it pulls the rubber out of the crimp or tears the bladder. this is the same reason you do not want tanks sitting on the self too long. Tanks are designed to be in service and any time the tank is either empty or over filled (under aired) you are significantly lowering the life of any tank.