| 摘要 |
<p>A fluid measurement gauge is principally used to measure the fluid level in large underground storage tanks, such as for storing gasoline at service stations. A housing (12) is positioned vertically in the fluid and includes a leadscrew (30) which is driven by a stepper motor (100). A nut (176) is mounted for longitudinal movement along the leadscrew. A float (160) encircles the housing and includes a magnet (164) at the surface of the fluid level. A magnetic sensor, such as a Hall-effect switch (188) is mounted on the nut and driven in selected steps downward to encounter the magnet mounted in the float. A reference position is marked at the top of the housing and the fluid level is measured downward from the reference position by detecting the magnet by operation of the magnetic sensor. An additional float (166) can be provided to detect the interface between two fluids such as gasoline and water. The second float is further provided with a magnet (168) to be detected by the magnetic sensor. In addition, temperature sensors (150,152,154), such as thermistors, can be mounted near the housing to measure the temperature of the fluid for compensation to standard conditions. An electronic circuit board (112) can be included within the fluid measurement gauge to provide an integral unit for making periodic, unattended fluid measurements.</p> |
