A pneumatic timer or timing relay is similar to a control relay, except that it contains contacts that are designed to operate_____?

• A. At a specific time, interval
• B. Continuously
• C. Only on power-up
• D. At random times

Answer: (A)

Pneumatic timers are built to create a controlled delay before the contacts change state. They incorporate a timing element that holds the output in one condition and then actuates after a preset interval, using the flow of compressed air to produce the delay. This means the contacts operate at a specific time interval, which is essential for sequenced or staged operations in a control system.

Unlike a plain control relay, which switches as soon as the coil is energized or de-energized, a pneumatic timer intentionally delays that change. It isn’t designed to switch continuously, nor only on power-up, nor at random times—the whole point is a predictable, fixed delay before the contact action.