Plumbers, what might this be?

[mogger]

My son in laws acreage. Is the white piping a de-gasser? or for cushioning water hammer. From well to bottom of the unit and then about 15 inches up, over to pressure tank.

[B-MAC]

Looks like there is an automatic bleeding valve on top of the upright white pipe
May say "Auto-Vent" on it, they use them on hot water heating systems to vent off air in system.
I would say it is for de-gassing

[CaberTosser]

I would agree with the de-gassing theory, the presence of the automatic air vent at the top of the arrangement would prevent it from functioning as a hammer-arrester because it would bleed out any air-cushion. Being primarily a city plumber I've not dealt with many wells though so I could stand to be corrected on this educated guess. (a number over the years certainly, but nothing with de-gassing or treatment)

[zeek]

[roger]

yah mogger, that is definately a farm-bred degasser. that is a maid-o-mist air removal device. when you first showed me your phone jpeg i took it to be a 3/4" ball valve not a device.
this design would function much the same way that a boiler scoop would remove air from a hot water heating boiler.
i didnt think the sons in law place is an H2S area but depending on the amount of water flow, gas type, quality and the suspected volume of gas, a vent to outdoors could be considered.
to be the most effective the water has to be static enough to allow the gases to rise out and break surface tension or baffled to allow the gas to 'shake' out of the water, like getting rid of carbonation in soda. im sure others here can add specifics but for the most part its pretty ingenious.