| 摘要 |
<p>24 FLUID MEASUREMENT GAUGE 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 is positioned vertically in the fluid and includes a leadscrew which is driven by a stepper motor. A nut is mounted for longitudinal movement along the leadscrew. A float encircles the housing and includes a magnet at the surface of the fluid level. A magnetic sensor, such as a Halleffect switch, 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 can be provided to detect the interface between two fluids such as gasoline and water. The second float is further provided with a magnet to be detected by the magnetic sensor. In addition, temperature sensors, 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 can be included within the fluid measurement gauge to provide an integral unit for making periodic, unattended fluid measurements.</p> |
