Which type of valve is required for individual ASME pressure vessels?

The requirement for a manual shutoff valve in individual ASME (American Society of Mechanical Engineers) pressure vessels is critical for safety and operational efficiency. Manual shutoff valves allow operators to isolate a pressure vessel from the rest of the system in situations where maintenance, inspection, or emergency procedures are necessary. This control ensures that the pressure can be safely released or maintained during any system adjustments or repairs.

Furthermore, these valves are designed to be operated by hand, empowering the operator to make definitive safety choices when managing the pressure vessel. This direct control over the flow provides peace of mind, as it prevents accidental releases or uncontrolled flow of gas, which is especially vital when dealing with compressed natural gas.

Other types of valves, while useful in different contexts, do not fulfill the same requirements. Automatic shutoff valves operate without manual intervention and are typically used in scenarios where automatic closure is necessary to prevent overpressure or other hazards. Backflow check valves are crucial for preventing reverse flow in a system but do not allow for isolation of the vessel. Excess-flow check valves are designed to close if a flow rate exceeds a certain threshold, helping protect the system from excessive flow but again lacking the manual control aspect needed in this context.

Thus, the manual shutoff valve is