| 摘要 |
A system is shown for injecting a chemical, such as an odorant, from a chemical supply into a fluid containing system such as a natural gas pipeline or an LPG pipeline. A tank of odorant is maintained under a positive pressure which exceeds that of the pipeline. An injection conduit communicates the odorant tank with the pipeline. A precise control flow valve, located within the injection conduit, meters odorant to be injected into the pipeline. An ultrasonic measuring unit allows the odorant to be metered on a drop wise basis with drops of chemical being counted as they pass through the flow valve into the injection conduit and into the natural gas pipeline. The ultrasonic measuring unit also allows steady state flow conditions to be measured accurately. A sonic measuring unit can also be utilized in low flow situations.
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