Asian Journal of Physical and Chemical Sciences

Liquefied petroleum gas (LPG) leakage poses a significant safety risk in domestic and light-industrial environments, particularly where conventional detectors provide only local alarms without automated intervention or remote monitoring. This study designed and implemented a smart IoT-based LPG leakage detection system integrating an MQ-6 LPG sensor, MQ-2 smoke sensor, flame sensor, ESP32 microcontroller, normally closed gas solenoid valve, ventilation fan relay, buzzer, and locally hosted web dashboard. Circuit design and simulation were undertaken in Proteus 8.2 Professional, while system firmware was developed in the Arduino Integrated Development Environment. The prototype was assembled on a Vero board and housed in a ventilated enclosure. Under controlled tests, gas concentrations above programmed thresholds triggered the buzzer, closed the gas supply valve, activated forced ventilation, and updated the local IoT dashboard. The MQ-6 sensor achieved 97.3% detection agreement, while combined detection agreement across the sensing arrangement reached 98.6%. The average LPG alarm response time was 1.8 s, the dashboard update time averaged 1.9 s, and no false alarms were recorded during 72 h of continuous operation. These findings demonstrate that the prototype can combine local hazard detection, automatic physical intervention, and offline-capable monitoring within a single system. The design is intended for domestic and light-industrial LPG safety applications in resource-constrained settings.