How many fuel shutoff valves are minimum required for group III flame effects?

The correct answer is that two fuel shutoff valves installed in series are the minimum required for group III flame effects. This requirement is based on safety protocols established by NFPA 160 to ensure an effective control of fuel supply in flame effects, which can pose risks if not properly managed.

Having two shutoff valves means that if one valve were to fail or malfunction, the second valve still provides an additional layer of safety, effectively preventing unintended fuel release and thereby reducing the risk of uncontrolled flame effects. The requirement for these valves to be installed in series further enhances safety, as it ensures that both valves must be opened for fuel to flow, which adds an additional measure of safety.

This configuration is important in environments where group III flame effects are used, as these settings often involve more complex and hazardous flame effects compared to lower groups. Ensuring redundancy in fuel shutoff mechanisms is crucial for protecting both the audience and the performers involved.

The alternative options do not meet the minimum safety standards set forth in the NFPA 160. For instance, a single shutoff valve lacks the necessary redundancy and may lead to increased risks if it fails. Three shutoff valves, either installed in series or parallel, go beyond the minimum requirement, adding complexity and potentially unnecessary components