Final answer:
NFPA 51 states that a flashback arrestor/check valve should be installed at the regulator, at the torch backflow, or on the manifold in a welding or cutting pipe system to prevent reverse flow of gases and protect against flashbacks.
Step-by-step explanation:
The National Fire Protection Association (NFPA) Standard 51 is concerned with the design and installation of oxygen-fuel gas systems for welding, cutting, and allied processes. According to NFPA 51, there are three options for placing the required protective flashback arrestor/check valve in a manifold pipe system to improve safety during these operations. First, the arrestor/check valve can be installed at the regulator. Second, it can be placed at the backflow on the torch. Lastly, it can be situated on the manifold between the header and the torch.
It's important to balance safety and functionality in the system design, and NFPA 51 provides guidance on achieving that through these options. Regardless of the location chosen, the flash arrestor/check valve's role is to prevent the reverse flow of gases and extinguish any flashback flames, thereby protecting personnel and equipment from potential hazards.
Preventing unsafe conditions is vitally important, and other safety devices such as a ground fault circuit interrupter (GFCI) are also used in electrical systems to prevent shock by detecting unintended paths of current flow.