The Allen-Bradley 849A-ZOD25 Pneumatic Timing Relay is an electro-pneumatic timer that has been designed and manufactured by Allen-Bradley in the 849 Timing Relays series. It is designed to be an easy-to-configure timing device for a variety of applications. This pneumatic timing relay will retain the electrical status of its contacts after the coil is energized for a user-defined amount of time before changing the contacts from the normally open status to the closed status. The Allen-Bradley 849A-ZOD25 Pneumatic Timing Relay is simple to adjust by simply turning a screw-type needle valve to regulate the speed of the air that is flowing inside the pneumatic mechanism. When installing and maintaining this pneumatic timer, it is of utmost importance to guarantee a clean and dry air supply because dirt or excess moisture inside the machine will eventually lead to unexpected failure.

The Allen-Bradley 849 series 849A-ZOD25 Pneumatic Timing Relay has some interesting advantages when compared to the standard electrical timers, such as being immune to high levels of humidity and to variations in atmospheric pressure and/or the environmental temperature. This device can be installed in both outdoor and indoor applications, but as with any other kinds of industrial control equipment, the manufacturer strongly recommends placing it in a protected enclosure in order to extend its operating lifespan. With proper protection, this timing relay can even be used in explosive environments. The Allen-Bradley 849A-ZOD25 Pneumatic Timing Relay is completely adjustable by the final users by large and small degrees to suit the needs of any application. The variations in the speed of the outgoing air in this pneumatic relay are directly proportional to the time that it takes the switch to move from one electrical contact status to the other.