Electronic gas blender and gas flow control mechanism therefor

A gas flow control mechanism for a gas blender comprising:

• a voltage sensitive orifice defining a passage for each gas to be controlled and having an inlet port in fluid communication with a gas source and an outlet port in fluid communication with a plenum for mixing at least two gases;
• and
• a gas flow controlling means, placed in a feed back loop, to adjust a gas flow exiting from the orifice to a preset value, comprising:
• a linear gas flow resistor in fluid communication with the exiting gas flow;
• a differential pressure transducer placed in a feed back loop for measuring pressure drop across the gas flow resistor;
• and
• a comparator responsive to a signal generated by the transducer and adapted to continuously monitor and compare the existing gas flow with the preset value;
• and an analogue computer to calculate and generate an appropriate voltage signal required to provide the total gas glow and concentration of the preset value.

A gas flow control mechanism for a gas blender comprising:

• a voltage sensitive orifice defining a passage for each gas to be controlled and having an inlet in fluid communication with a gas source and an outlet in fluid communication with a plenum for mixing at least two gases;
• a normally open solenoid valve in parallel connection with the orifice to bypass the orifice;
• a gas flow controlling means, placed in a feed back loop, to adjust flow of gas exiting from the orifice to a preset value, comprising:
• a gas flow resistor in fluid communication with the gas exiting from the orifice and adapted to provide a linear flow resistance to the gas traversing therethrough which is low enough to allow sufficient gas flow at a minimum gas source pressure;
• a differential pressure transducer placed in a feed back loop to the flow resistor;
• and
• a comparator responsive to a signal generated by the transducer and adapted to continuously monitor and compare the existing gas flow with the preset value;
• and an analogue computer to calculate and generate an appropriate voltage signal required to provide the total gas glow and concentration of the preset value;
• and
• including a needle valve and a rotameter through which the gas exiting from the solenoid valve and the flow resistor traverses before entering the plenum.