Spunding Valves are used extensively in Germany to naturally carbonate beer with the CO2 generated from the fermentation. Naturally carbonated beers often have brighter flavors and a more consistent mouthfeel. Also because the carbonation is done during fermentation there is no oxygen pick up by transferring it to a keg after fermentation is complete and prior to force carbonation.
Relieves pressure while filtering from one keg to another while also letting you read the pressure in the receiving keg.
Note: The very end of the pressure relief valve can be adjusted by unscrewing to adjust the pressure. If tight, and not adjustable by hand, it needs to be loosened with pliers. Wrap a towel around the end piece of the pressure relief valve (about the last 1/4 in) and loosen with pliers. Then finger tighten or loosen to desired pressure.
Gauge reads 0 - 15 psi