Which valve is permitted between the safety valve and the boiler?

In the context of boiler safety and operation, the correct practice is to have no valves installed between the safety valve and the boiler. The purpose of a safety valve is to prevent excessive pressure from building up within the boiler; it serves as a critical safety component designed to relieve pressure immediately and reliably.

If any valve were installed between the boiler and the safety valve, it could potentially hinder the safety valve's ability to function. For instance, a closed valve could prevent steam from escaping in a pressure situation, leading to dangerous conditions including the risk of a boiler explosion.

Safety regulations and best practices dictate that the safety valve must be directly connected to the boiler without any intervening valves. This ensures that in the event of an overpressure situation, the safety valve will operate without any obstructions, providing the necessary protection to the system and its operators.