PBW is a great cleaner for wine tanks, lines, pumps, etc.. It is non-hazardous buffered alkaline brewery that will often out perform more hazardous caustic chemicals without removing the flesh off your bones. Because it is not rated as a hazardous item it can ship FedEx ground, greatly reducing shipping costs. It will not corrode soft metals. PBW stands for Powder Brewery Wash, as the product was originally marketed to breweries.
When mixing hot water and PBW in an air or water tight space, it will create pressure. Please use caution when using PBW in enclosed equipment.