Patent ID: 7263448

Claim:
A continuous flow chemical metering apparatus, comprising: a conduit adapted to be connected as part of a chemical injection line downstream of a chemical storage tank and upstream of a chemical injection device for controlling injection of chemical drawn from the chemical storage tank through the chemical injection line; a measuring vessel adapted to hold a column of fluid, the measuring vessel being in fluid communication with the conduit; an automated valve for controlling flow through the conduit, the automated valve being positioned upstream of the measuring vessel; means for determining head pressure of the measuring vessel, including at least one sensor; and a processor capable of being calibrated to establish calibration data regarding the relationship between head pressure and a height of the column of fluid in the measuring vessel, the processor being adapted to control the automated valve and to receive data from the at least one sensor, the processor controlling a continuous testing cycle in which the automated valve is closed when the height of the column of fluid in the measuring vessel reaches a predetermined height so that chemical drawn by the chemical injection device partially empties the measuring vessel, and then the automated valve is reopened so that chemical drawn by the chemical injection device is drawn from the chemical storage tank while the height of the column of fluid in the measuring vessel again has an opportunity to rise to the predetermined height, the processor determining flow rate by monitoring signals from the at least one sensor and performing calculations using the calibration data and current data regarding dynamic changes to head pressure.