Supriya Fail-Safe Actuators are engineered for safe actions under system failure. System being "Fail-Safe" does not mean that failure is impossible or improbable, but rather the system is designed to prevent or mitigate unsafe consequences from system failure. In case of Pneumatic Fail-Safe Actuators when failure happens, system is designed to respond in a way that will cause no harm to equipment or environment or people.

The causes of failure / Failure Modes could be

1. loss of source air,
2. loss of pneumatic signal,
3. loss of solenoid power or electric signal.

The Fail-Safe Actions for each Failure Models could be

1. Stay-Put (Fail Last)
2. Fail to Close (Air to Open)
3. Fail to Open (Air to Close)

1. Supriya Double Acting Actuator with Fail Safe Action Stay-Put

Stay-Put or Lock-Up or Fail-Last Pneumatic Actuators are designed to hold the valves in the last operating position upon air/signal failure. Sensing Valve is used to monitor the status of air / signal. Upon failure the sensing valve operates to exhaust the pilots to the two air-lock valves. These airlock valves, in turn, hold the existing pressure on both sides of the piston, thus locking it in place to maintain the last throttling position. Supriya Actuators are suitable for ON-OFF Duty and Control Duty. Refer sample hook-up drawings below.

2. Spring Return Type

Spring Return Actuators are designed, engineered and adopted for optimum performance under heavy duty and harsh service environments. Supriya customized 'design-tools are built to provide heavy duty, reliable and economical solution for spring return actuators.

1. Fail Safe Action: Fail Close

Supriya Pneumatic Spring Return Actuator Type Fail Close is designed to match the valve thrust / torque characteristics, enabling Valve to Close under Failure modes. The Fail-Safe action of Valve Closure is by spring. Supriya Actuators are suitable for ON-OFF Duty and Control Duty.

2. Fail Safe Action: Fail Open

Supriya Pneumatic Spring Return Actuator Type Fail Open is designed to match the valve thrust / torque characteristics, enabling Valve to Open under Failure modes. The Fail-Safe action of Valve Opening is by spring. Supriya Actuators are suitable for ON-OFF Duty and Control Duty. Refer sample hook-up drawings below.

3. Volume Tank or Air Vessel Type DAFS

Supriya Double Acting Fail Safe System is designed with integrated pneumatic circuit including Air Reservoir / Volume Tank to provide pressurized volume of air to drive the actuator piston in the direction of fail safe position. Supriya DAFS System is used primarily to close the valves and sometimes to open the valves under air failure. When the supply pressure drops below a preset value, pilot valve moves to a position to enable the air from volume tank to override the piston actuator in the direction of fail safe position. These actuators are field reversible, however the suitability of reversibility will be confirmed by the factory.

4. Booster Operated Compact Fail Safe System

Supriya Booster Operated failsafe units are an ideal choice for larger actuators as it eliminates bulky spring return actuators when limited space is available. Air to Air Pressure Booster with integrated automation circuit is coupled to charge the air vessel at elevated pressure. For instance, 7bar source air pressure can be used to charge the air vessel to 14bar without any external power. Significant reduction in size of actuator, volume tank (air vessel) and hence its weight can be achieved through this integration. Thereby, overall highly efficient compact air actuated fail safe system can be coupled to valve.