Which of the following is a characteristic of variable spring hangers?

Variable spring hangers are designed specifically to accommodate vertical thermal expansion. This characteristic is crucial in piping systems where temperature changes can cause the pipes to expand or contract. Since materials often expand when heated, fixed supports would inhibit this movement, leading to potential stress and damage in the system. Variable spring hangers provide a flexible solution that allows the pipes to move vertically while still offering support, ensuring the integrity of the system during thermal cycling.

In contrast, options stating that variable spring hangers support fixed loads only or cannot accommodate thermal movements misrepresent the functions of these hangers. They are not suitable for all types of pipes as specific applications may require different support systems based on the load, movement, and environmental factors associated with the piping.