The 2-way pneumatic relay R1 (Direct or Reverse) is typically used together with a pneumatic switch to block or put back valves. It can also be used in pneumatic instruments as secondary element. When the registered pressure reaches the setting relay value, this sends a pneumatic signal to the switch producing a variation in their state. Its main function is to register the pressure in service line.

The EPTA® pneumatic switch relay RM2 is a 5-way and 2-stage switch, which is used together with a group of pneumatic switches to block and restore valves  Manually /Automatically using a pneumatic signal.