Where should stop valves not be located in an NH3 safety system?

The reasoning behind the choice of not locating stop valves downstream of the safety devices is rooted in the importance of maintaining the integrity and functionality of those safety devices. Safety devices, such as relief valves, are critical to the safe operation of an ammonia (NH3) system, as they prevent overpressure situations that could lead to catastrophic failures or leaks.

If a stop valve is placed downstream of safety devices, it can obstruct the normal operation of these devices during a pressure relief scenario. This means that if a situation arises where the pressure needs to be relieved, the relief valve may be unable to engage and allow excess pressure to escape. This scenario creates a significant safety hazard, as the intended protection mechanism becomes ineffective, leading to potentially dangerous conditions.

Therefore, it is crucial to position stop valves in a manner that does not impede the functioning of safety devices, ensuring that they can perform their intended role effectively in maintaining safety and preventing accidents in the NH3 system.