Compound refrigeration system

Claim 1

IN A COMPOUND REFRIGERATION SYSTEM HAVING A PLURALITY OF EVAPORATORS ADAPTED TO OPERATE A PLURALITY OF SEPARATE AND INDEPENDENT REFRIGERATED FIXTURES SUBJECTED TO AMBIENT AND VARYING LOAD CONDITIONS AND MAINTAINING SUCH FIXTURES WITHIN THE INCLUSIVE RANGE OF REFRIGERATION TEMPERATURES OF ABOUT 50* F. TO ABOUT -20* F., CONDENSER-RECEIVER MEANS FOR SUPPLYING LIQUID REFRIGERANT TO ALL OF SAID EVAPORATORS, SEPARATE FIRST AND SECOND SUCTION HEADER MEANS, AT LEAST TWO SERIALLY CONNECTED AND CONTINUOUSLY OPERATING COMPRESSORS HAVING DIFFERENT SUCTION PRESSURES, THE EVAPORATORS ADAPTED TO OPERATE IN THE UPPER RANGE OF REFRIGERATION TEMPERATURES EACH BEING CONNECTED TO SAID FIRST SUCTION HEADER MEANS, SAID FIRST SUCTION HEADER MEANS CONNECTED DIRECTLY TO THE SUCTION SIDE OF THE DOWNSTREAM COMPRESSOR, THE EVAPORATORS ADAPTED TO OPERATE IN THE LOWER RANGE OF REFRIGERATION TEMPERATURES EACH BEING CONNECTED TO SAID SECOND SUCTILN HEADER MEANS, SAID SECOND SUCTION HEADER MEANS CONNECTED DIRECTLY TO THE SUCTION SIDE OF THE UPSTREAM COMPRESSOR, SAID UPSTREAM COMPRESSOR RECEIVING A CONTINUOUS AND RELATIVELY STABLE LOAD FROM SAID EVAPORATORS OPEATING IN THE LOWER RANGE OF REFRIGERATION TYEMPERATURES TO ASSURE THE CONTINUOUS OPERATION THEREOF AND SAID UPSTREAM COMPRESSOR ADDING SAID RELATIVELY STABLE LOAD TO A FLUCTUATING LOAD RECEIVED BY THE DOWNSTREAM COMPRESOR.