find force at bottom of closed tank column

Digital signals coded in any of a number of protocols (e.g., Foundation Fieldbus, Hart, Honeywell DE, Profibus, and RS-232) are the most robust, but the older technologies such as RS-232 can handle only limited distances. Current loops can carry signals over longer distances with less degradation. The simplest and oldest industrial signal communication is 4-20 mA current loops (where the loop current varies with the level measurement) are the most common output mechanism today. Analog voltages are simple to setup and deal with, but may have serious noise and interference issues. Useful transducer output signal formats for computer automation are current loops, analog voltages and digital signals. This requires sending data in a machine-readable format from the sensor to the control or monitoring system.

When more complex physical principles are involved, emerging technologies often use computers to perform the calculations. Hydrostatic head measurements have also been widely used to infer level. A simple float having a specific gravity between those of the process fluid and the headspace vapor will float at the surface, accurately following its rises and falls. Other level-detection devices include those based on specific gravity, the physical property most commonly used to sense the level surface.

They are therefore being rapidly replaced by more advanced technologies. It can be stated without reservation that conventional sight glasses are the weakest link of any installation.

Seals are prone to leak, and buildup, if present, obscures the visible level. The material used for its transparency can suffer catastrophic failure, with ensuing environmental insult, hazardous conditions for personnel, and/or fire and explosion. A manual approach to measurement, sight glasses have always had a number of limitations. The simplest and oldest industrial level measurement device is, of course, the sight glass.

Find force at bottom of closed tank column