When is the outlet pressure of the second-stage regulator limited to 2.0 psig?

The outlet pressure of the second-stage regulator is limited to 2.0 psig when the regulator seat disc is removed because this condition directly impacts the functionality of the regulator. The seat disc is a critical component that helps maintain the proper sealing and pressure regulation for gas flow. When the seat disc is removed, the regulator loses its ability to maintain the desired pressure control and is typically set to a maximum of 2.0 psig as a safety feature. This limitation is crucial to prevent over-pressurization of the downstream systems, which could lead to potential leaks or dangerous conditions.

In other situations such as during installation, routine maintenance, or shutdown, the typical pressure setting and functionality are not necessarily impacted by the removal of the seat disc. The outlet pressure would follow normal operating procedures, and the system would be tested and calibrated accordingly without the same immediate safety risk associated with the missing seat disc.