Working Principle :
Gas alarm device detects combustible gases like natural gas or LPG. It detects any or a mixture of metan (CH4), propane (C3H8) and butane (C4H10) gases.
When 230VAC 50Hz power is applied to detector, green led turns on. After preheat time of 1.5minute it will be ready for gas leakage detection. No test gas should be applied to the device during preheat time. When concentration of gas leakage is above alarm level, detector goes into alarm mode and gives audible alarm within 10 seconds and red led turns on. In this mode, if detector relay output is connected to a solenoid valve, it shuts off the gas flow. As long as gas concentration is above alarming level, device stays in alarm mode. When gas concentration drops below alarm level, detector goes into watching mode and it is ready for further detection. When electricty is cut off, the device does not work. During possible gas leakage, in order to automatically activate any available external devices such as fan, shut off valve, siren, 230VAC relay output should be connected to those devices at installation. Maximum allowed current drawn from relay output is 7A. As long as total output current is below maximum allowed current limit of 7A, any number of devices can be connected to the relay ouput.
Basic Information :
Gas Alarm device is designed to detect gas leakage of natural gas, LPG and coal gas at domestic premises. It is an always on electrical device with fixed installation. By use of its relay output, during gas leakage it is able to switch on devices like fan, shut off valve, siren.
For combustible gases minimum concentation level which does not cause any combustion in the environment is called LEL (lower explosive limit), shown in percentage volume. For natural gas (metan) LEL is %5 and for lpg LEL is %2. Gas alarm device gives visible and audible alarms well before these LEL values.
Alarm level for natural gas is 0.5% (five in thousand) or 5000ppm (five thousand parts per million)
Alarm level for LPG is 0.3% (three in thousand) or 3000ppm (three thousand parts per million)