The primary function of the pressure tank in a pumped water system is to protect the pump motor, which is accomplished by storing water under pressure so the pump does not have to come on every time there is a small, intermittent demand for water.
The amount of drawdown capacity is determined by a formula known as Boyle's Law, and February's “Tech Topics” covers this formula and how to apply it to real-life conditions.
The fundamentals of pumped water systems continues this month by examining how calculate the pressure drop due to friction loss in a typical residential system.