In a steam boiler, what should never be placed between the safety relief valve and the boiler vent?

In a steam boiler system, the safety relief valve is a critical component designed to prevent overpressure situations by releasing excess steam. It is essential that nothing which could interrupt the flow or operation of this safety device is placed between the safety relief valve and the boiler vent.

A shut-off valve, when placed in this location, poses a significant risk because, if it were closed during a pressure buildup in the boiler, it would prevent the safety relief valve from functioning properly. This could lead to dangerously high pressure within the boiler, resulting in catastrophic failure or explosions. Therefore, ensuring that the line remains unobstructed and always allows for the immediate release of pressure is paramount to maintaining the safety and integrity of the boiler system.

Understanding the implications of placing other devices like check valves, pressure gauges, or flow regulators is different, as these do not inherently create a barrier that could prevent the operation of the safety relief valve under emergency conditions. However, they also have their proper placements in a system that do not interfere with safety features.