Which requirement is needed for unattended CNG compression equipment?

The requirement of having a high discharge and low suction automatic shutdown control for unattended CNG compression equipment is crucial for ensuring safety and operational efficiency. This mechanism actively monitors the pressure levels within the system. In the event that pressure exceeds a safe threshold (high discharge) or drops below a necessary level (low suction), the automatic shutdown control intervenes to halt operations. This is particularly important in unattended settings, where an operator's immediate presence is not guaranteed to manage unusual conditions or emergencies.

Implementation of these automatic shutdown controls significantly reduces the risk of dangerous situations such as over-pressurization, which can lead to equipment failure or potential explosions, as well as operational inefficiencies due to insufficient suction that could harm the compressor.

While other options may highlight important aspects of CNG operations, such as the need for operator presence or monitoring, they do not specifically address the essential safety mechanism that allows the equipment to operate unattended without increasing risks. The requirement for automatic controls underscores the importance of maintaining safety standards in unattended operational environments.