This month, “Tech Topics” covers conventional and captive-air tanks. There are two primary reasons for having a pressure tank in a pumped water system.
There are two types of pressure tanks - captive-air tanks (also called pre-charged, diaphragm or bladder tanks), and conventional tanks (also known as hydro-pneumatic, galvanized, ASME and epoxy-lined tanks). Using the term “hydro-pneumatic” to describe a conventional tank is a bit of a misnomer. All pressure tanks used in the ground water industry are hydro-pneumatic, meaning they contain water (hydro) and air (pneumatic). In this article, we will use the terms “captive air” and “conventional” to differentiate the two types of tanks.