Which type of valve is required to be upstream of each gas pressure regulator?

The requirement for a manual gas shutoff valve upstream of each gas pressure regulator is primarily for safety and operational purposes. This valve allows for the manual control of gas flow through the system, which is crucial in situations where maintenance, repair, or emergency shutdown is necessary. By having this valve in place, personnel can easily and effectively isolate the gas supply, ensuring that any work performed downstream of the valve can be done safely without the risk of gas leaks or unintended gas flow.

Additionally, the use of a manual gas shutoff valve contributes to compliance with safety regulations and industry standards, which emphasize the importance of having accessible shutoff mechanisms. This valve type provides a means of conveniently cutting off the gas supply in an emergency, enhancing the overall safety of the gas delivery system.

In contrast, the other valve types serve different functions or may not meet the specific requirement for manual control and isolation of gas flow. Automatic shutoff valves, for instance, are designed to close in response to certain conditions but may not provide the same ease of access or manual control. Check valves prevent backflow but do not isolate the system when needed. Three-way valves allow for the diversion of flow but do not necessarily serve as a means of shutting off the gas supply entirely.