butterfly valve vs garrotte

butterfly valve

noun
  • A valve with a disk-shaped mechanism which can be used for isolating or regulating flow. 

garrotte

noun
  • A cord, wire or similar used for strangulation. 

  • An iron collar formerly used in Spain to execute people by strangulation. 

verb
  • To execute by strangulation. 

  • To suddenly render insensible by semi-strangulation, and then to rob. 

How often have the words butterfly valve and garrotte occurred in a corpus of books? (source: Google Ngram Viewer )