Gas detection apparatus

Claim 1

AN APPARATUS FOR DETECTING THE PRESENCE OF A GAS CONSTITUENT IN A MEDIUM BY THE USE OF A SUBSTANCE IN GAS PERMEABLE FORM, WHICH UNDERGOES A PHOTOCHARACTERISTIC CHANGE IN THE PRESENCE OF SAID GAS, SAID APPARATUS COMPRISING: A LIGHT TRANSMITTING CONTAINER CONSTRUCTED TO SUPPORT SAID SUBSTANCE FOR PASSAGE OF GAS THERETHROUGH, A CONDUIT CONNECTED TO SAID CONTAINER HAVING TWO OPENINGS AT ONE END THEREOF, A TUBE FOR CONDUCTING THE MEDIUM TO BE TESTED TO THE CONTAINER CONNECTED TO ONE OF SAID OPENINGS, A SOURCE OF RESTORING GAS INCLUDING AN OUTLET TUBE CONNECTED TO THE OTHER OF SAID OPENINGS, A VALVE SO ARRANGED THAT WHEN IN A FIRST POSITION IT CLOSES THE OPENING CONNECTED TO THE SOURCE OF RESTORING GAS AND WHEN IN A SECOND POSITION IT CLOSES THE OPENING CONNECTED TO THE TUBE FOR CONDUCTING THE MEDIUM TO BE TESTED, A LAMP AND A PHOTOELECTRIC CELL ARRANGED TO RECEIVE LIGHT FROM THE LAMP THROUGH THE CONTAINER, AND ELECTRICAL VALVE SHIFTING MEANS OPERATED BY SAID PHOTOELECTRIC CELL TO SHIFT SAID VALVE.