Early warning of Gas Leakage and detection of smoke helps to restrict the damage, stop the explosion.
Gas Leakage Detectors can detect presence of gas at 10% of LEL. LEL is a concentration of the gas in air when it becomes explosive. With early detection of gas leakage accidents can be avoided.
Smoke detectors detect the presence of smoke. It is said "where there is smoke, there is FIRE". Early detection of fire helps to take action to prevent the fire from spreading further.