For piping systems in gas or vapor service, what is the permissible minimum flow rate?

The permissible minimum flow rate for piping systems in gas or vapor service is important for ensuring effective system operation and preventing issues such as condensation or inadequate transport of the gas. A minimum flow rate of 1.3 feet per second is typically specified because it helps maintain a velocity sufficient to avoid condensation of heavier gaseous components and to facilitate efficient gas transport.

At this flow rate, the system is better able to transport gases without risking the accumulation of liquid or contaminants along the pipeline, which can lead to operational inefficiencies or even damage to the piping system. This flow rate strikes a practical balance between minimizing energy costs and ensuring the integrity and functionality of the piping system under varying pressure and temperature conditions.

Other flow rates, such as 0.5, 2.0, and 3.0 feet per second, are not typically recommended as they may either be too low to prevent issues with condensation or excessively high, which could lead to increased wear and tear on the system components. Thus, the choice of 1.3 feet per second as the minimum flow rate is guided by these operational considerations in the design and maintenance of gas and vapor piping systems.