System for introducing noxious gas into an exposure chamber

A system for introducing noxious gas into an exposure chamber containing plants which are to be exposed, under controlled conditions over long periods of time, to an atmospheric gas which has been given a defined composition by the introduction of the noxious gas, said system comprising in combination:

• separate inlet conduits for the noxious gas and for the atmospheric gas;
• a respective mass flow regulator connected in each said inlet conduit;
• a respective shut-off valve connected in each said inlet conduit downstream of the respective said flow regulator;
• an electronic control circuit means for controlling said flow regulators to regulate the respective flows of the atmospheric and noxious gases to be mixed, and for jointly switching said shut-off valves between open and closed positions in response to input control signals;
• a premixer stage means, connected to each of said inlet conduits downstream of said shut-off valves, for homogeneously mixing atmospheric and noxious gase flowing through the respective said inlet conduits;
• a buffer reservoir for the thus composed mixture of atmospheric and noxious gases connected to the outlet of said premixer stage means;
• and
• a computer controlled dosaging means, connected to the outlet of said buffer reservoir, for dosaging the mixture of atmospheric and noxious gases for the exposure chamber.