Gas weights compensation method for liquid depth gauging system
AssigneeFluid Data Systems
InventorEugene A. Glassey
Life of this patent
Estimating the term…
Abstract
A method and apparatus for monitoring liquid levels using pressure responsive instruments is described, in which an arrangement for compensating for the effects of errors including gas weights errors is provided. The required compensation factor for a particular installation is first calculated theoretically, and then used in order to raise the output signal of the instrument electronically by the calculated factor. In one arrangement, the output signal is amplified by the desired factor. Alternatively, the excitation voltage of the instrument itself, or of a potentiometer used to interface the instrument to electronic data acquisition devices, is varied in order to raise its output voltage by the desired compensation factor.
Claims16
A method of measuring a liquid level in a body of liquid, comprising the steps of:
- sensing the hydrostatic pressure at a submerged level close to the bottom of a body of liquid to produce a pressure signal dependent on said hydrostatic pressure;
- applying the pressure signal as an input to a pressure responsive instrument having an output proportional to the pressure input;
- calculating an error compensation factor to compensate for predetermined errors in the pressure signal including gas-weights errors;
- connecting the output signal of the pressure responsive instrument to compensation means for amplifying the output by said calculated compensation factor;
- and
- connecting the amplified output to a data acquisition means for monitoring said hydrostatic pressure.
A pressure responsive liquid level measuring system, comprising:
- a pressure sensing device having a pressure signal dependent on the hydrostatic pressure at a submerged level in a body of liquid to be monitored;
- a pressure responsive instrument having an input for connection to said pressure signal and a signal output proportional to the pressure applied at its input;
- drive means responsive to said signal output for producing an output voltage drive signal for driving a data acquisition device;
- said drive means including variable electrical compensation means for varying said drive signal by a predetermined amount corresponding to a predetermined compensation factor including gas weights error.
A pressure responsive liquid level measuring system for measuring the level of a body of liquid, comprising:
- a bubbler device for sensing the hydrostatic pressure at a submerged level in the body of liquid and producing an output pressure signal dependent on said hydrostatic pressure;
- a spring restored pressure transducer connected to said bubbler device and having input means for application of the output pressure signal to the transducer and output means for producing an output voltage dependent on said output pressure signal;
- compensation means for changing said output voltage by a predetermined compensation factor to produce a compensated output signal;
- and
- readout means driven by said compensated output signal to provide a reading indicating said hydrostatic pressure.
A pressure responsive liquid level measuring system for measuring the level of a body of liquid, comprising:
- a bubbler means communicating with the body of liquid at a submerged level for producing a pressure signal dependent on the hydrostatic pressure at said submerged level, said pressure signal including predetermined errors including gas-weights errors;
- a pressure responsive instrument having an input for connection to said pressure signal, said pressure responsive instrument comprising a balanced beam manometer having an output data shaft driven by a motor to balance the beam;
- drive means connected to said output data shaft to produce a drive signal responsive to rotation of said data shaft, said drive means including variable compensation means for varying said drive signal by a predetermined compensation factor corresponding to said errors in said pressure signal;
- and
- data acquisition means responsive to said compensated drive signal to produce a readout proportional to pressure at said submerged level.
Dependencies are inferred from the claim text.