The detectors GAMMA 652-O/M and GAMMA 652-O/G are gas detector of methane and LPG gas, that warns with an optical and acoustic signal, the presence of gas in the environment. They are planed to be functioning as detected gas with relay exit. The detectors serie GAMMA are calibrated to detect gas up to 10% of the L.E.L. (Low Explosion Limit), this threshold can change in base of the environmental conditions but it will not gets over during the first 4 years working, the 15% LEL, after that period the instrument have to be put out of order or re-send to Geca S.r.l. for a complete substitution of the device.