Final answer:
Automatic excess flow valves should be installed as per the manufacturer's instructions to ensure proper functionality and safety. Local building codes, national plumbing code, and international safety standards may also impose additional requirements.
Step-by-step explanation:
Where automatic excess flow valves are installed, they shall be listed, sized, and installed in accordance with the manufacturer's instructions. This is critical to ensure that the valves function properly in the event of an emergency, such as a sudden break in a gas or fluid line,
which they are designed to help seal off. Adhering to the manufacturer's instructions takes precedence because it includes specific details related to the installation, performance parameters, and limitations of the particular valve. It should be noted, however, that it is also important to comply with any applicable local building codes, national plumbing code, and international safety standards as they can mandate additional requirements. Any discrepancies between these sources should be addressed by consulting with local code officials or industry experts to ensure compliance with all relevant safety and professional standards.