What is a requirement for every cylinder in a CNG vehicle?

For every cylinder in a CNG vehicle, it is essential that it is equipped with either a manual valve or a shutoff valve. This requirement is crucial for safety and operational efficiency. The valve allows the driver to control the flow of gas from the cylinder, enabling them to shut off the gas supply during emergencies, maintenance, or any situation where it is necessary to stop the flow of compressed natural gas.

Having a manual valve provides the driver with immediate, direct control, while a shutoff valve can be used in automated systems to ensure safety without manual intervention. This requirement is a fundamental aspect of CNG vehicle design to prevent leaks and to ensure that gas does not escape uncontrollably, which could pose safety hazards.

The other options presented do not align with safety standards or operational norms for CNG cylinders. For instance, a temporary valve is not a standard requirement and may not provide the reliability needed, while the absence of any valves would render the cylinder useless for regulation of gas flow. Similarly, only having remotely actuated valves would not meet the immediate needs of a driver for manual control in various scenarios.