Design and Construction of a Compressed Natural Gas Pressure Monitoring System for Domestic Cylinders in Port Harcourt

The growing adoption of compressed natural gas as a cooking fuel alternative to liquefied petroleum gas in Port Harcourt, Rivers State, creates a need for reliable pressure monitoring systems that alert users to critically low gas levels and potential over-pressure conditions to prevent accidents. This project presents the design and construction of a CNG cylinder pressure monitoring system using a piezoelectric pressure transducer interfaced with an Arduino Uno microcontroller. The sensor measures cylinder pressure within the range of 0 to 200 bar, and the microcontroller converts the sensor output to a calibrated pressure reading displayed on an OLED screen. Audible and visual alerts are triggered when pressure falls below a minimum safe delivery threshold of 5 bar or exceeds a maximum safety threshold of 180 bar. A SIM800L GSM module sends SMS notifications to the registered user's phone number under both alarm conditions. The prototype was calibrated against a certified Bourdon tube pressure gauge across nine pressure reference points between 10 and 150 bar. Measurement accuracy was within plus or minus 2 bar across the tested range. The system was bench-tested for 30 days under continuous operation, consuming an average of 80 milliampere-hours per day from a 3.7-volt lithium polymer battery, yielding an estimated battery life of five days between charges. The study identifies the need for intrinsically safe explosion-proof enclosure design as a critical requirement for commercial deployment in fuel storage environments. Keywords: CNG monitoring, pressure transducer, domestic gas safety, microcontroller, Port Harcourt