Gas chamber Gas chamber A gas chamber is an apparatus for killing humans or other animals with gas, consisting of a sealed chamber into which a poisonous or asphyxiant gas is introduced. The most commonly used poisonous agent is hydrogen cyanide; carbon dioxide and carbon monoxide have also been used. Gas chambers were used as a method of execution for condemned prisoners in the United States beginning in the 1920s and continue to be a legal execution method in three states. During the Holocaust, large-scale gas chambers designed for mass killing were used by Nazi Germany as part of their genocide program.
Diesel exhaust is often combined with a particulate matter (PM) filter in the exhaust. In turbocharged engines, EGR needs a controlled pressure differential across the exhaust manifold and intake manifold, which can be met by such engineering as use of a variable geometry turbocharger, which has inlet guide vanes on the turbine to build exhaust backpressure in the exhaust manifold directing exhaust gas to the intake manifold. It also requires additional external piping and valving, and so requires additional maintenance. John Deere, the farm equipment manufacturer is implementing such a combined SCR-EGR design, in a 9-liter "inline 6" diesel engine that involves