There are two main types of smoke alarm tech, says Raman Chagger, principal consultant at BRE, the Building Research Establishment. Ionisation-based systems use a tiny amount of radioactive material to charge, or ionise, particles in the air which flow between two small plates. Should smoke interrupt that flow of charged particles, the alarm goes off.
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Timestamps (CTC or TDT):
Radio 2 in the Park will take place at City Park between 7 and 9 August.。同城约会对此有专业解读