SU1144013A1 - Pressure pickup dynamic graduation method - Google Patents

Abstract

METHOD FOR DYNAMIC 1TADUATION OF PRESSURE SENSORS by acting on the hydrostatic pressure sensor of a liquid column followed by abrupt pressure changes, characterized in that, in order to simplify and improve graduation accuracy, the sensor is first immersed in the liquid upward with a sensitive element, and then the liquid is reported to move relative to the pressure sensor with the acceleration of free fall and at the moment of contact of the sensitive element with the free surface of a moving liquid column ayut abrupt pressure change.

Description

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four; The invention relates to instrumentation, in particular to methods for the calibration and testing of pressure sensors. There is a method of dynamic calibration of pressure sensors by creating a pressure jump, which consists in blocking the gas-tight chamber with a diaphragm into two parts. The test pressure sensor is placed into one part and an overpressure is created in it relative to the other part of the chamber, and a pressure-dependent change in pressure is obtained by destroying the diaphragm L. This method is cumbersome, since for its realization a pressure increase system (for example, a compressor) is required. When dynamically calibrating pressure sensors in this way, the transient process — consisting in calming the sensitive element after an abrupt change in pressure — occurs in a gaseous medium. This leads to the fact that during dynamic calibration of fluid pressure sensors in this way, the effect of the added fluid mass on the natural frequency of the sensitive element of the sensor is not taken into account, which reduces the accuracy of dynamic calibration of fluid pressure sensors using this method. The closest in technical essence and the achieved effect to the proposed method is a dynamic calibration of pressure sensors by applying a sensor to the hydrostatic pressure of a liquid column followed by a sudden change in pressure 2. A known method is that the pressure sensor is placed in a vertical helical vessel, mounted on the support, and loaded, filling the water at the required depth. The initial immersion of the pressure transducer into water determines the magnitude of the amplitude of the test pressure. A sudden change in pressure is obtained by abruptly removing the support or suspension of the vessel with the liquid and the pressure sensor placed in it, with the result. The vessel with a pressure sensor placed in it begins to move with the acceleration of free fall under the influence of gravity, which leads to an abrupt decrease in pressure on the walls of the vessel and on the sensor. The known method is complex and does not provide sufficient precision calibration. In the dynamic calibration of pressure sensors in a known manner, the jump amplitude is limited by the depth (height) of the vertical vessel. Thus, to obtain a pressure jump with an amplitude of 1.10 Pa, it is necessary to have a vertical vessel 10 m deep. The aim of the invention is to simplify and increase the accuracy of the calibration. The goal is achieved by calibrating pressure sensors by acting on the hydrostatic pressure sensor of a liquid column with a subsequent abrupt pressure change, the sensor is immersed in the liquid upward with a sensitive element, and then the liquid column is informed of movement relative to the sensor with an acceleration of free fall and at the moment of contact of the sensitive element with An abrupt change in pressure is obtained by the free surface of a moving liquid column. FIG. 1 shows a diagram of the device; to implement this method in fig. 2 is a graph of pressure change versus time at a sensor element. The device includes (Fig.1) vertical pipeline 1; quick action of hydraulic lock 2, calibrated sensor 3, catapult device 4, pipeline 5 for supplying liquid, drain tank, 6, recorder 7 and generator 8 of time stamps (H height of filled part of vertical pipeline 1, measured from calibrated sensor 3 to upper end of pipe 1, H} is the height of the free-fall section, fluid, is traced from the water seal 2 to the bottom of the drainage tank 6. The height Hji H). High-speed hydrolock 2 with katupultira device 4 is placed in the lower end of the vertical pipe 1, which is installed in the drain tank 6. Between the pipe 1 and the drain tank

6 is a free fall section of the liquid.

Graduated sensor 3 is installed upward with a sensitive element and located in the lower pipe of vertical pipeline 1 under the high-speed hydraulic lock 2, pipeline 5 for supplying liquid is located in the upper part of vertical pipeline 1. Registrar 7 is connected to graduated sensor 3 and generator 8 of time stamps.

After installing graduated. sensor 3, the lower opening of the vertical pipe 1 is hermetically sealed with a vial seal 2, after which the ejection device 4 is charged and pipe 1 is filled

to the height H of the working fluid supplied through the pipeline 5.

On start signal, the catapult device 4 opens the guide-. rozatvor 2 and the liquid begins its movement along the vertical pipeline 1 with the acceleration of free pday. The registrar 7 fixes the readings of the calibrated pressure sensor 3 together with the time stamps of the generator 8.

At the moment of contact of the sensing element with the free surface of the fluid moving inside the vertical pipeline with the acceleration of free fall, an abrupt decrease in pressure occurs.

FIG. Figure 2 shows a plot of pressure on a sensor element (ordinate axis) versus time (abscissa axis), calculated from the beginning of the movement of a liquid column (vessel C liquid): 1 — time variation of hydrostatic pressure on the sensor element; 2 is the change in pressure over time on the sensitive element of the sensor due to the velocity head; 3 is the total pressure P (t) on the sensitive element. sensor element.

The proposed method makes it possible to increase the accuracy of the dynamics of pressure sensors.

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Claims (1)

~ METHOD OF DYNAMIC GRADING OF PRESSURE SENSORS by exposing the sensor to the hydrostatic pressure of a liquid column followed by an abrupt change in pressure, characterized in that, in order to simplify and improve the accuracy of calibration, the sensor is first immersed in the liquid with the sensitive element up and then the liquid column the bones communicate movement relative to the pressure sensor with the acceleration of gravity and at the moment of contact of the sensing element with the free surface of the moving column of liquid receive an abrupt change in pressure. In particular, to methods for testing sensors, a method for dynamically measuring pressure sensors by means of a gas-tight chamber