Which valve must be present between the safety valve and the boiler?

The presence of no valve between the safety valve and the boiler is critical for ensuring the safety and proper functioning of the system. The safety valve is designed to automatically relieve pressure that exceeds a predetermined level to prevent potential explosions or damage to the boiler. If a valve were placed between the safety valve and the boiler, it could potentially create a blockage that would prevent the safety valve from functioning properly. This could lead to dangerous pressure buildup within the boiler, negating the safety purpose of the valve.

In addition, having no valve allows the safety valve to respond freely to overpressure situations, ensuring that it can perform its critical role in safeguarding the boiler's operation. It's vital that these components are connected directly to ensure immediate and unobstructed response during emergency situations.

This understanding highlights the importance of maintaining clear and direct pathways in pressure relief systems, reinforcing the principle that safety valves must be directly equipped on vessels to function effectively in emergency scenarios.