My Grandmother's dementia is progressing to the point where we are worried about her safety alone at home all day. She is still rather capable at times but also has increasing periods of missing meals, medication and not being able to manage the heating. My grandmother uses the gas cooker to heat milk for her breakfast and we're keen to support this routine of hers whilst making it as safe as possible. I have come across gas safety valves being used behind cookers. Please can someone explain what they do and how they work? Thanks!