Pressure Reduction
PRS/Gas trains consists of,
Ball valves: this isolates the system from main supply or isolates the either side of PRS & is also used and Drain Valves to release the pressure as and when required.
Slam shut off Valve: Slam shut off valves is installed before pressure regulator. Slam shut off valve close the supply of gas when a downstream pressure exceeds a pre-determined limit.
Pressure regulator: Pressure regulator maintain downstream pressure at certain quantity of gas, irrespective of variation in upstream pressure from maximum to minimum limit. Spring loaded or Pilot operated pressure regulators are used.
Relief valves:
- Creep relief Valve: A slight weeping of pressure regulator/ increase in downstream due to rise in downstream surrounding temperature result in increasing the downstream pressure to dangerous level, such creep pressure is blown off through creep relief valve.
- Safety Relief Valve: The safety relief valve set at higher pressure than slam shut off valve so that the safety relief valve will operate when slam shut off valve fails to operate.
Pressure gauges: To monitor upstream and downstream pressure, the pressure gauges are installed. Isolation valve is provided with each pressure gauge for easy replacement of pressure gauges in case of failure.