Process control system

Claim 1

APPARATUS FOR PRODUCING AN AQUEOUS SOLUTION OF AMMONIUM NITRATE OF PREDETERMINED CONCENTRATION WHICH COMPRISES MIXING MEANS TO CONTACT NITRIC ACID WITH AMMONIA, EVAPORATING MEANS HAVING HEATING MEANS ASSOCIATED THEREWITH, MEANS TO PASS AMMONIUM NITRATE FROM SAID MIXING MEANS TO SAID EVAPORATING MEANS, MEANS TO WITHDRAW AMMONIUM NITRATE FROM SAID EVAPORATING MEANS, A VESSEL, MEANS TO PASS A SAMPLE OF AMMONIUM NITRATE TO SAID VESSEL FROM SAID MEANS TO WITHDRAW, MEANS TO COOL SAID VESSEL, MEANS TO MEASURE THE TEMPERATURE OF AMMONIUM NITRATE IN SAID VESSEL, MEANS RESPONSIVE TO SAID MEANS TO MEASURE, TO ESTABLISH A PNEUMATIC PRESSURE REPRESENTATIVE OF THE TEMPERATURE OF AMMONIUM NITRATE IN SAID VESSEL, FIRST AND SECOND BELLOWS, MEANS RIGIDLY SUPPORTING FIRST ENDS OF SAID BELLOWS SO THAT THE SECOND ENDS THEREOF ARE IN FACING SPACED RELATIONSHIP, A ROD CONNECTING THE SECOND ENDS OF SAID BELLOWS SO THAT EXPANSION OF ONE RESULTS IN COMPRESSION OF THE OTHER, A FIRST CONDUIT HAVING A FIRST END THEREOF COMMUNICATING WITH THE INTERIOR OF SAID FIRST BELLOWS, A SECOND CONDUIT HAVING A FIRST END THEREOF COMMUNICATING WITH THE INTERIOR OF SAID SECOND BELLOWS, THE EFFECTIVE CROSS-SECTIONAL AREA OF SAID SECOND CONDUIT MEANS BEING SMALLER THAN THE EFFECTIVE CROSSSECTIONAL AREA OF SAID CONDUITS TO SAID MEANS TO ESTABLISH A PNEUMATIC PRESSURE, A MEMBER ADJUSTABLY SECURED TO SAID ROD SO AS TO MOVE WITH SAID ROD, MEANS POSITIONED ADJACENT SAID MEMBER A PRESELECTED DISTANCE IN A SECOND DIRECTION OPPOSITE SAID FIRST DIRECTION IN RESPONSE TO MOVEMENT OF SAID ROD IN ANOTHER SECOND DIRECTION, MEANS RESPONSIVE TO SAID MEANS TO DETECT MOVEMENT TO ADJUST THE HEATING MEANS ASSOCIATED WITH SAID EVAPORATING MEANS.