Stationary land boilers: commonly used main safety valve type Select the safety valve design typically employed on stationary boilers, where orientation is fixed and compactness is less critical than reliability and constancy of set pressure. Choose the correct option.

Concept
For stationary land boilers, the classic choice is the dead-weight safety valve, which maintains an accurate set pressure by calibrated weights and is unaffected by vibration/tilt (suitable when the boiler is fixed in place). Locomotive/marine boilers usually employ spring-loaded valves due to motion and space constraints.

Clarifications
A high-steam/low-water device is a protective combined valve/sensor but not the standard main safety valve type across stationary plant.

Final Answer
Dead-weight safety valve