An LEL monitor may trip safety systems such as the ventilation system.

• A. True
• B. False
• C. Sometimes
• D. Only during maintenance

Answer: (A)

LEL monitors detect the concentration of flammable gases in the air and are tied into the plant’s safety controls. When the detected level reaches the preset limit, the safety system can be triggered to take protective actions, such as activating or increasing ventilation to dilute and remove the vapor. Ventilation is a common safeguard used to lower gas concentration and reduce ignition risk, so it’s appropriate for the monitor to trip the ventilation system when needed. The point is that this action may occur under the system’s design and setpoints, making the statement true.