201  propane  (LPG)/natural  gas  alarms  are state-of-the-art  inflammable  gas  detectors with  an  internal  sounder.Advanced  electronics  in  conjunction  with  a semiconductor  gas  sensor  provide early detection  of  propane  gas,  with  high  immunity against  unwanted  alarms.Models  are  available  powered  by  AC  mains or  from  a  DC  12/24  V  supply  (such  as  a security  system).