What additional measure is needed if a second gas pressure regulator is installed in series?

If a second gas pressure regulator is installed in series, it is designed to enhance the control over gas pressure and flow quality. The operation of multiple regulators in a series setup does not inherently require the installation of additional valves. The primary goal of having multiple regulators is often to achieve a specific reduced pressure stage — one regulator can handle coarse regulation while the next refines it.

In many scenarios, the existing system might already contain the necessary shutoff valves, which can adequately regulate or isolate the gas flow without the need for an extra valve. Hence, the installation of an additional manual shutoff valve is not typically needed unless specific safety or operational protocols dictate otherwise for the unique installation. This is especially relevant in environments where redundancy in safety mechanisms might be critical.

While reverse flow indicators and pressure gauges are used for monitoring and safety, they are not mandatory just because there is a second regulator in the system. The crucial aspect here is that the operational requirements and the safety measures already present can suffice without needing another valve, provided the initial setup meets all regulatory standards and safety guidelines.