Gas control device for controlling the fuel gas and oxidizing agent supply to a burner in an atomic absorption spectrometer

A device for controlling fuel gas and oxidizing agent supplied to a burner (45) in an atomic absorption spectrometer, comprising:

• a fuel gas line (14) for supplying fuel gas to said burner (45);
• an oxidizing agent supply conduit (38) for supplying an oxidizing agent to said burner (45);
• a first oxidizing agent supply line (10) for supplying a first oxidizing agent to said oxidizing agent supply conduit (38);
• a second oxidizing agent supply line (12) for supplying a second oxidizing agent, having a higher oxygen content than said first oxidizing agent, to said oxidizing agent supply conduit (38);
• a control unit (28);
• a first restrictor (58) and a first pressure regulator (54) disposed in said fuel gas line;
• a second restrictor (44) and a second pressure regulator (40) disposed in said oxidizing agent supply conduit (38);
• the regulators being connected upstream of the restrictors, respectively;
• first (56) and second (46) servomotors connected to said first and second pressure regulators, respectively;
• each of said servomotors being connected to receive signals from said control unit (28) for adjusting the pressure settings of said pressure regulators, respectively;
• a 3/2-directional solenoid control value (34) connected between said oxidizing agent supply conduit (38) and said first oxidizing agent supply line (10) in a first valve position, and said 3/2-directional solenoid control valve (34) being connected between said oxidizing agent supply conduit (38) and the second oxidizing agent supply line (12) in a second valve position;
• said solenoid control valve (34) being connected to receive signals from said control unit (28) for controlling the valve position;
• a first shut-off solenoid valve (30) disposed in said first oxidizing agent supply line (10), said first shut-off solenoid valve being connected to receive signals from said control unit (28) for controlling the first shut-off solenoid valve;
• a second shut-off solenoid valve (50) disposed in said fuel gas line upstream of said first pressure regulator (54), said second shut-off solenoid valve (50) being connected to receive signals from said control unit (28) for controlling the second shut-off solenoid valve position;
• a first pressure sensor (16) disposed in said first oxidizing agent supply line (10) upstream of said first shut-off solenoid valve (30), said first pressure sensor being connected to send signals to said control unit (28) responsive to the pressure in the first oxidizing agent supply line (10);
• a second pressure sensor (18) disposed in said second oxidizing agent supply line (12) upstream of said 3/2-directional solenoid control valve (34), said second pressure sensor being connected to send signals to said control unit (28) responsive to the pressure in the second oxidizing agent supply line (12);
• a third pressure sensor (20) disposed in said fuel gas line upstream of said second shut-off solenoid valve (50), said third pressure sensor being connected to send signals to said control unit (28) responsive to the pressure in the fuel gas line (14).