Which device is used to connect gas cylinders to a central piping system?

The device that is used to connect gas cylinders to a central piping system is the manifold. A manifold serves as a central point that allows multiple gas cylinders to be connected and combined in a way that ensures a steady supply of gas to the central piping system. It can handle the switching of cylinders, ensuring that when one cylinder is empty, the system automatically draws from another, thus maintaining an uninterrupted supply of gas.

In the context of other options, while a master valve is crucial for controlling the flow of gas in the system and a regulator is responsible for reducing and regulating the pressure of the gas from the cylinders to a suitable level, neither of these components serve the primary function of connecting multiple cylinders to the central system. Similarly, a compressor is used to pressurize gases but is not involved in the direct connection of gas cylinders to piping systems. Therefore, the manifold is the appropriate choice as it specifically facilitates the connection and management of multiple gas sources in a controlled manner.