Asphalt oil tank monitor

In an apparatus to monitor the quantity of liquid contained in a tank, of the type which includes:

• a pipe probe inserted downward into the tank and reaching near the bottom of the tank;
• an air pump connected pneumatically to the probe, to displace the liquid from the probe until air bubbles escape from the bottom end of the probe, whereupon the air pressure within the probe is proportional to the height of the liquid in the tank;
• a piezoresistive pressure transducer for measuring the probe air pressure;
• a pneumatic connection between the probe and the transducer;
• an electronic process controller, connected electrically to and working in concert with the transducer to produce a voltage whose value is proportional to the probe air pressure;
• and a numeric digital readout to report that voltage directly in volts, or to report the voltage in terms of selected engineering units as programmed into the controller according to the controller manufacturer's instructions using appropriate conversion factors and tank volumetrics;
• the improvement comprising:
• air tank means, appended pneumatically to the connection between the probe and the pressure transducer, for buffering the probe air pressure against insignificant small variations associated with the evolution of individual air bubbles at the end of the probe, resulting in the readout being free from jittery variations in the least significant figure.