Nitrous oxide bypass ramp for six cylinders RPZA-6 Automatic oxygen by-pass ramp for six cylinders in a cabinet RPAK-6-Sh Discharge ramp for nitrous oxide for two cylinders ????-2 Automatic bypass ramp for carbon dioxide for four cylinders RPAU-4-SH Discharge ramp for ammonia for five cylinders RRAM-5 Nitrous oxide discharge ramp for three cylinders RRZA-3 Automatic oxygen bypass ramp for four cylinders RPAK-4 Discharge frame for acetylene for two cylinders ????-2 Automatic bypass ramp for oxygen on two cylinders RPAK-2 Methane discharge ramp for six cylinders RRM-6