When does the effect valve close in a flame effect system?

In a flame effect system, the effect valve is designed to close on the loss of the hold-open signal. This is essential for safety and control purposes, as the hold-open signal indicates that conditions are safe for the flame effect to operate. If this signal is lost—due to a failure in the control system or another safety concern—the valve automatically closes to prevent any uncontrolled release of gas or fuel that could lead to a hazardous situation. This automatic closure serves as a critical safety feature to protect both the audience and performers.

The other options, while they may involve aspects of the system’s operation, do not accurately reflect the safety mechanism related to the effect valve’s closure in terms of maintaining safe operational conditions. For example, simply activating control power does not ensure safety, as it may not correspond to the conditions necessary for a flame effect. Regular maintenance checks are intended to keep systems functioning properly but do not pertain to the automatic closure mechanism during performance. Additionally, a power surge may cause various system malfunctions, but it’s the loss of the hold-open signal that specifically triggers the closing of the effect valve in a flame effect system.