Where must the pressure relief device be vented to?

The pressure relief device must be vented to the atmosphere to ensure safety and proper functionality. This requirement is crucial because the primary purpose of a pressure relief device is to prevent the buildup of excessive pressure within a system, which could lead to catastrophic failures or explosions. By venting the device to the atmosphere, it allows any excess pressure to dissipate safely without affecting other system components, maintaining the integrity of the tank and associated infrastructure.

Venting to the atmosphere ensures that the harmful gases or excessive pressure do not pose a risk to the system itself or create hazardous conditions for individuals nearby. It also prevents the risk of trapping gas or liquids inside a closed system, which could lead to dangerous pressure fluctuations.

In contrast, venting to a fuel tank or high pressure line would create a risk of over-pressurization and defeat the purpose of the pressure relief device. Venting into a vacuum chamber would not be applicable in this context, as it is not designed to handle the release of pressure in this manner. Therefore, venting to the atmosphere is the most effective and safest option for managing excess pressure in CNG systems.