Indicating filters are designed to signal the operator, when the element needs cleaning. There are various types of indicators, such as color-coded, flag, pop-up, and swing arm. The element is designed so it begins to move as the pressure increases due to dirt accumulation. One end is linked to an indicator that shows the operator just how clean or dirty the element is. Another feature of this type of filter is the ease and speed with which the element can be removed and replaced. Most filters of this kind are designed for inlet line installation.

Indicator post is used in fire protection systems and performs two functions. First it provides a means to operate a buried or otherwise inaccessible valve and second it readily and clearly indicates whether the valve is open or shut. Adjustable type indicator post design has a built-in 18″ adjustment span.