What type of valve may be placed between the boiler safety valve and the atmosphere on the discharge pipe from the valve?

The correct choice indicates that no valve can be located between the boiler safety valve and the atmosphere on the discharge pipe. This is essential for maintaining safety and functionality in boiler systems.

The safety valve is designed to release excess pressure from the boiler to prevent dangerous situations, such as explosions. If any type of valve were placed in the discharge line, it could malfunction or become blocked, potentially allowing pressure to build up in the boiler beyond safe limits. This could prevent the safety valve from performing its critical function of relieving pressure, which is a fundamental safety feature.

By ensuring that there are no valves in this position, the system guarantees that the safety valve can operate freely and respond immediately to any rise in pressure, effectively maintaining the integrity and safety of the boiler system.