Why is to safety valve mounted on boiler drum?

the safety valve is mounted on the top of drum because, if the water level in boiler decreases a certain value, the temperature gets increased in water drum because of lack of water. So, increase in temperature result in high pressure in steam drum, as the safety valve is designed to withstand a certain pressure, after a cetain pressure, the safety valve is removed by high pressure of steam. this is why the safety valve is mounted on top of boiler drum.

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Shall we sort out that lot? That answer is wrong. Its only link with water-level is that the valve has to be above the water anyway. If the boiler runs dry the safety-valve will not protect it.

The safety-valve is there to prevent the steam pressure rising to a potentially a dangerous level. It is set to open at the boiler's designed working pressure.