Smell was coming from drains. Explosive gas detected by TIF 8800 A. I opened windows and it's cleared.
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Exell Battery 2.4V 1000mAh Gas Meter Battery for TIF 8800 Combustible Gas Detector Saft: 405421 405421-00 405421-000 405421100 8806A Tif: 8800A 8806A ...
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