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FEMA FD Maximum Pressure Limiters for LPG Systems

FEMA FD maximum pressure limiters are used for safe pressure monitoring in LPG systems. They switch when a defined maximum pressure is reached and help prevent inadmissibly high pressure values from remaining present in the system. The devices are specifically designed for applications in LPG technology and are suitable for safety-related shutdown functions in plants, pipelines and supply systems.

The FD series is designed for a setting range of 3 to 16 bar. Depending on the version, variants with external or internal lockout are available. Type FD16-326 features external lockout, while type FD16-327 is equipped with internal lockout. The switching differential is 0.3 to 1.0 bar for FD16-326 and 1.5 to 3.0 bar for FD16-327.

The pressure limiters of the FD series are built according to the specific requirements of LPG technology. All wetted parts are made of stainless steel 1.4104 and 1.4571. The pressure sensor is self-monitoring: in the event of a measuring bellows failure, the pressure limiter switches to the safe side.

The devices are intended for intrinsically safe control circuits and must not be connected directly to mains voltage. Operation requires a suitable isolating switching amplifier. In combination with the isolating switching amplifier, the control circuit can also be monitored for wire breakage and short circuit.

Typical Applications

• Maximum pressure monitoring in LPG systems
• Safety shutdown in case of inadmissibly high pressure
• Monitoring of pipelines, vessels and supply systems
• Use in intrinsically safe control circuits
• Applications requiring lockout and manual reset
• Pressure monitoring in LPG systems and comparable technical installations

Advantages of FEMA FD Maximum Pressure Limiters

• Specifically designed for LPG systems: suitable for safety-related applications in LPG technology
• Setting range 3–16 bar: suitable for typical maximum pressure monitoring in LPG applications
• With lockout function: available with external or internal lockout of the switching state
• Self-monitoring pressure sensor: switches to the safe side in the event of measuring bellows failure
• Wetted parts made of stainless steel: materials 1.4104 and 1.4571
• Ex-i operation possible: for intrinsically safe control circuits with suitable isolating switching amplifier
• Line monitoring: short-circuit and wire-break monitoring possible in combination with an isolating switching amplifier

FEMA FD Pressure Limiters at ICS Schneider

ICS Schneider offers FEMA FD maximum pressure limiters for LPG systems in different versions. Available variants include FD16-326 with external lockout and a switching differential of 0.3 to 1.0 bar, as well as FD16-327 with internal lockout and a switching differential of 1.5 to 3.0 bar.

When selecting the correct device, the required switching point, type of lockout, switching differential, permissible operating pressure, electrical connection, requirements for intrinsically safe operation and integration into the safety chain should be considered. Since these are safety-related pressure limiters, the design should always be checked based on the plant data and applicable regulations.

FAQ – Frequently Asked Questions about FEMA FD Maximum Pressure Limiters

1. What is a FEMA FD maximum pressure limiter?

A FEMA FD maximum pressure limiter is a mechanical safety switching device used to monitor a maximum permissible pressure in LPG systems. When the set pressure is reached, the device switches the control circuit to the safe side.

2. What applications is the FD series designed for?

The FD series is specifically designed for LPG systems. It is used for maximum pressure monitoring, safety shutdown and protection of system components against inadmissibly high pressure values.

3. Which types are available?

Available versions include FD16-326 with external lockout and FD16-327 with internal lockout. Both versions have a setting range of 3 to 16 bar.

4. What is the difference between FD16-326 and FD16-327?

The FD16-326 has an external lockout implemented in the control cabinet. The FD16-327 has an internal mechanical lockout directly on the pressure limiter. The two versions also differ in their switching differentials.

5. What does lockout mean for a pressure limiter?

Lockout means that the switching state is maintained after triggering. This prevents the system from restarting automatically. Operation can only be released again after pressure reduction and reset.

6. How is the FD16-327 reset?

The FD16-327 is reset directly on the device. After sufficient pressure reduction, the lockout is released by pressing the red button on the scale side of the pressure switch.

7. How is the FD16-326 reset?

The FD16-326 is reset externally, for example via a latching relay in the control cabinet. The exact implementation depends on the safety-related circuit of the system.

8. Can a FEMA FD pressure limiter be connected directly to mains voltage?

No. FEMA FD pressure limiters must not be connected directly to mains voltage. They are intended for intrinsically safe control circuits and must be operated with a suitable isolating switching amplifier.

9. Which materials are used for the wetted parts?

The wetted parts are made of stainless steel 1.4104 and 1.4571. This makes the devices robust for the intended applications in LPG systems.

10. What does self-monitoring pressure sensor mean?

Self-monitoring means that the pressure limiter switches to the safe side in the event of a measuring bellows failure. This helps prevent a dangerous failure state.

11. What protection rating does the FD pressure limiter have?

The FEMA FD pressure limiters are designed with protection rating IP65, provided they are installed according to the specified requirements.

12. What mounting position is specified?

The specified mounting position is vertical with the switching device facing upwards. This mounting position should be considered during planning and installation.