| 摘要 |
The invention detects the presence of a liquid or liquid flow, and it is used to control pumping of a well when the quantity of liquid being discharged by the pump per stroke is much less than the volumetric displacement of the pump. A fluid flow detector 96 includes a single thermally conducting body 98, a first heater 100 for heating the first end or portion 97 of the thermally conducting body 98, a first temperature detector 108 for detecting the temperature of the first portion 97 of the thermally conducting body 98, first insulation material 122 for thermally insulating the first portion 97 of the thermally conducting body 98, second insulation material 136 for thermally insulating the second end or portion 99 of the thermally conducting body 98, a second heater 106 for heating the second portion 99 of the thermally conducting body 98 and a second temperature detector 110 for detecting the temperature of the second portion 99 of the thermally conducting body 98, all being inside a closed-ended stainless steel tube 102 protruding inside of conduct 104. The thermal conductivity of the second insulation material 136 is greater than that of first insulation material 122. One embodiment also includes an electrical bridge 112 for comparing the relative rates of heat loss between the first portion 97 and second portion 99 of the thermally conducting body 98.
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